Chemistry A Molecular Approach, 2E Nivaldo J. Tro Solution Manuals.pdf (22)

Chapter 20. Organic Chemistry Teaching Tips

Suggestions and Examples •

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•

Benzene and other aromatic compounds do not undergo addition reactions like alkenes do.

Benzene is conveniently drawn with alternating double bonds, but the hexagon with the inscribed circle brings better attention to the actual bonding picture.

Polycyclic aromatic compounds are often made from fused benzene rings, i.e. rings that share common sides.

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20.8 Functional Groups •

The OH group in an alcohol or carboxylic acid is not a hydroxide ion. Instead, there is a covalent bond between the oxygen and the carbon.

The use of examples and common physical or chemical properties will help some students remember the different functional groups.

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20.9 Alcohols •

• •

Misconceptions and Pitfalls

Alcohols contain a hydroxyl group like carboxylic acids but are considerably less acidic.

The hydroxyl group can be attached at any position on a carbon chain; sugars have an OH group at virtually every carbon.

Alcohols can react by replacing the O (substitution) or by elimination.

The oxidation state of a carbon can be determined by the number of bonds to oxygen. An alkene is equivalent to an alcohol, and an alkyne is equivalent to an aldehyde.

Oxidizing agents remove hydrogen while reducing agents add hydrogen to the carbon in question.

For exam and test prep, contact 291 excellentessaywriters@gmail.com .

Chapter 20. Organic Chemistry Lecture Outline

Terms, Concepts, Relationships, Skills • • Structure: C=O bonded to C or H -al suffix Names oaldehydes: o ketones: -one suffix • o

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Figures, Tables, and Solved Examples

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Figure 20.6 Common Aldehydes and Ketones Figure 20.7 The Nutty Aroma of Almonds Figure 20.8 The Fragrance of Raspberries Figure 20.9 Charge Density Plots of the Carbonyl Group

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Properties and examples flavors and aromas: vanillin, • cinnamaldehyde, benzaldehyde, carvone, 2o Reactions o heptanone, ionone o oxidation • reduction addition Charge density plots 20.11 Carboxylic Acids and Esters • o Structure o acid: C=O bonded to OH • Names oester: C=O bonded to OR o acid: -oic suffix + acid • o ester: -oate suffix Properties and examples o o • tart or sour taste of acids sweet and fruity smells of esters Reactions o acid–base reactions of carboxylic acids condensation 20.12 Ethers • • • Structure: ROR Names: o use group name(s) of R Properties and examples o solvents anesthetics

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• • •

Figure 20.10 Common Carboxylic Acids and Esters Figure 20.11 The Tart Taste of Limes Figure 20.12 The Aroma of Pineapple

• Figure 20.13 Ethers

For exam and test prep, contact excellentessaywriters@gmail.com 292 .

Chapter 20. Organic Chemistry Teaching Tips

Suggestions and Examples •

•

Misconceptions and Pitfalls Both aldehydes and ketones contain C=O, but aldehydes must have the C=O on a terminal carbon, whereas ketones cannot have the C=O on a terminal carbon.

The carbonyl contains a polar bond with the electron density on the oxygen. This is the basis of considerable reactivity, as discussed in an organic chemistry course but made obvious in charge density plots like those in Figure 20.9.

20.11 Carboxylic Acids and Esters •

• •

Carboxylic acids are formed from a C=O attached to an OH, making them the most common examples of weak acids.

Esters are formed from a C=O attached to an OR and are derived from alcohols.

Carboxylic acids smell acrid and taste sour, while esters smell sweet and fruity. Examples for smelling are easy to acquire and circulate in class.

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20.12 Ethers •

The ether and ester names can be easily confused, and they are somewhat related structurally through the common OR group.

Some students may recognize that ethers are similar to esters. Ethers can be thought of as being derived from alcohols, whereas esters are derived from carboxylic acids.

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Chapter 20. Organic Chemistry Lecture Outline

Terms, Concepts, Relationships, Skills • • Structure: derivative of NH3 with one or more •• Names: alkyl groups + amine hydrogens replaced with alkyl groups o Properties o characteristic smell Reactions o acid–base condensation

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20.14 Polymers • o Repeating units o • covalently bonded Types omonomers o addition • o condensation

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Figures, Tables, and Solved Examples unnumbered figure: space-filling models of amines

• • • •

Examples o o polyethylene o polyvinyl chloride o polyurethane o polyethylene terephthalate nylon Kevlar

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unnumbered figures: space-filling models of ethylene, polyethylene Figure 20.14 Polyethylene Figure 20.15 Polyvinyl Chloride Table 20.11 Polymers of Commercial Importance Chemistry in Your Day: Kevlar

Chapter 20. Organic Chemistry Teaching Tips

Suggestions and Examples • • Amines behave much like ammonia: similar acid–base properties and similar smells.

Amines often appear in complex organic molecules used as drugs since the nitrogen can be protonated, making the molecule charged and rendering it more water soluble.

Misconceptions and Pitfalls

•

20.14 Polymers •

Not all of the macroscopic properties of polymers can be easily predicted by looking at the microscopic structure.

Polymers are ubiquitous. Many of the monomers are derived from petroleum, giving rise to concerns about price and continued availability. In part, this promotes the need or desire to recycle. The other reason for recycling is that many polymers do not readily decompose.

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Chapter 20. Organic Chemistry

Additional Problem for Naming Alkanes (Example 20.4)

Name the alkane:

Longest Chain Count the longest continuous chain of carbons. There are six carbons. The path straight across only includes five carbons in a row.

Substituents or Groups This compound has two substituents, both of which are named methyl.

Numbering Try numbering from the end at right. That would give “3,5-dimethyl.”

Numbering from the left gives smaller numbers “2,4-dimethy.l”

General Form Substituent number(s) + substituent name(s) + base name

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2,4-dimethylhexane This molecule can also be drawn as

Chapter 20. Organic Chemistry

Name the alkene:

Additional Problem for Naming Alkenes and Alkynes (Example 20.5)

Longest Chain Count the longest continuous chain of carbons that contains the double bond. There are six carbons.

The path straight across only includes five carbons in a row.

Counting from the left, the double bond is between the 3rd and 4th carbons; counting from the right gives the same outcome.

Substituents or Groups This compound has two substituents, both of which are named methyl.

Numbering Try numbering from the end at right. That would give “3,5-dimethyl.”

Numbering from the left gives smaller numbers “2,4-dimethyl.”

General Form Substituent number(s) + substituent name(s) + base name

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2,4-dimethyl-3-hexene

Chapter 21. Biochemistry Student Objectives

21.1• Diabetes and the Synthesis of Human Insulin Know that diabetes is a disease due to the absence or insufficiency of insulin, a protein synthesized in the pancreas that helps regulate cellular and blood glucose levels.

• Know that genetic engineering has allowed modified bacteria to produce human insulin, allowing it to be harvested for human use.

Know that biochemistry is the chemistry of living organisms, often involving macromolecules such as lipids, carbohydrates, proteins, and nucleic acids.

21.2• Lipids • • Give a general description of lipids with respect to structure and function.

• Know that fatty acids can be saturated (all C–C bonds) or unsaturated (at least one C=C bond). and understand understand that howfats theare tri-alcohol glycerol combines with fatty acids to form triglycerides.

• Know Know and solids and oils are liquids room temperature, a consequence Know that natural geometric isomers of unsaturated fatty acidsatare typically cis, that trans forms are of the structures of the fatty acids in triglycerides.

•

• • •

introduced when hydrogenation is used to control potential rancidity, and that trans fatty acids are

not considered healthful by nutrition experts.

Give a general description of phospholipids with respect to structure and function.

Draw and recognize representations of phospholipids and their role in lipid bilayers.

Recognize the structure of cholesterol and know that it serves as a structural component of cell membranes and as a precursor to other steroids in the body.

21.3• Carbohydrates • •

Know that carbohydrates are polyhydroxy aldehydes and ketones that are nutritional sugars and starches and that serve as energy sources for the body.

Recognize the general structures of monosaccharides like and glucose and fructose.

Know and understand how monosaccharides like glucose fructose form rings that can combine to make more complex structures such as disaccharides (e.g. sucrose) or polysaccharides (e.g. cellulose, starch, glycogen).

21.4• Proteins and Amino Acids • •

Know and understand that proteins are macromolecules that serve as structural components, enzymes, and hormones and have additional roles in transport, storage, protection, and mobility.

Know that there are 20 common amino acids and that ten essential ones must be consumed since the body cannot produce them from other molecules.

Know the general structure of amino acids, and write reactions for the formation of peptide bonds.

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Chapter 21. Biochemistry

21.5• Protein Structure • • Know that proteins are characterized as fibrous or globular. that protein of fouroflevels: primary, secondary, tertiary, and quaternary.

• Know Recognize the twostructure commonconsists components secondary structure, α-helices and β-pleated sheets, and • Know that the primary structure of a protein gives the sequence of amino acids.

• know that hydrogen bonding enables the formation of both.

Understand the different intermolecular interactions that maintain tertiary structure.

Know that multimeric proteins exhibit quaternary structure.

21.6• Nucleic Acids: Blueprints for Proteins • the basic structure of nucleic acids: sugars, bases, and phosphate • Understand Know and understand how the nucleotides are covalently combined to make alinks. single strand and how Define and understand codon, gene, and chromosome. two complementary strands form a double helix through hydrogen bonding.

21.7• DNA Replication, the Double Helix, and Protein Synthesis • Know process offrom DNAan replication.

Know and howunderstand proteins arethe synthesized RNA copy of DNA and understand how the codons direct the ribosome to attach particular amino acids to each other to make the specific protein sequence.

Section Summaries

• Outline Lecture • Terms, Relationships, Skills Figures,Concepts, Tables, and Solved Examples • Teaching Tips • Suggestions andand Examples Misconceptions Pitfalls

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Chapter 21. Biochemistry Lecture Outline

Terms, Concepts, Relationships, Skills • o Diabetes o • insulin biotechnology: genetic engineering Biochemistry

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21.2 Lipids •

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Intro figure: illustration of spiral timeline, structures of biomolecules

o Fatty o acid structure even number of carbons, C4 to C20 chains  

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Figures, Tables, and Solved Examples

• • • •

saturated  cis unsaturated  trans

o Glycerides o triglycerides   phospholipids phosphatidylcholine lipid bilayers o Cholesterol o membrane structure biosynthetic precursor to testosterone, estradiol

21.3 Carbohydrates • General structure: (CH2O)n • o Monosaccharides o carbonyl: aldehyde or ketone o o • OH groups cyclic form Disaccharides o • glycosidic linkage o sucrose (from glucose and fructose) Polysaccharides o o cellulose starch glycogen

• • • • • • •

unnumbered figures: Lewis structures, space-filling models of myristic acid, oleic acid Table 21.2 Fatty Acids Figure 21.1 The Effect of Unsaturation unnumbered figure: photo of lard package unnumbered figure: Lewis structure, space-filling model of tristearin, triolein Figure 21.2 The Formation of Tristearin Chemistry and Medicine: Dietary Fat: The Good, the Bad, and the Ugly Figure 21.3 Cis and Trans Fats Figure 21.4 Phosphatidylcholine Figure 21.5 Schematic for Phospholipid or Glycolipid Figure 21.6 Lipid Bilayer

cholesterol, testosterone, β-estradiol

unnumbered figure: Lewis structure of • • • • • • • •

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unnumbered figure: Lewis structure, spacefilling model of glucose, fructose Example 21.1 Carbohydrates and Optical Isomerism Figure 21.7 Intramolecular Reaction of Glucose to Form a Ring unnumbered figure: Lewis structures of ring forms of glucose, fructose, galactose Figure 21.8 Formation of a Glycosidic Linkage Figure 21.9 Hydrolysis of Disaccharides unnumbered figures: Lewis structures of cellulose, starch Figure 21.10 Hydrolysis of Polysaccharides

Chapter 21. Biochemistry Teaching Tips

Suggestions and Examples •

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Not all missing or damaged proteins can be replaced. Insulin is an example of one that can be.

There are several examples of essential proteins that are missing and can be replaced.

Diabetes affects about 11% of the population.

Other examples include human growth

hormone and thyroid hormone.

Biotechnology or genetic engineering is commonly used to make important proteins 21.2 Lipids • and biomedical molecules.

•

•

Misconceptions and Pitfalls

• The structural properties of fats and oils come primarily from the chain length and degree of unsaturation of the fatty acids.

Fatty acids and glycerol are the building blocks of triglycerides, the components of nutritional fats and oils. The space-filling models give a good sense of the shapes.

Melting points give a sense of how well the molecules can pack together.

Trans fats and the trans fatty acids from which they are made appear often in the nutrition literature and in the media. Trans fats do occur in nature but in small quantities.

The interactions of phospholipids with water make the membranes containing phospholipids even more stable.

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21.3 Carbohydrates •

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Monosaccharides occur primarily in the cyclic form in water.

When compared with the lipids, carbohydrate structures are more complex, including issues such as the nature of the monosaccharide, ring structures, and the glycosidic linkage between any two monosaccharides in more complex molecules.

The microscopic and macroscopic properties of the more complex sugars arise from the nature of the monosaccharides and the glycosidic linkages between them.

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Chapter 21. Biochemistry Lecture Outline

Terms, Concepts, Relationships, Skills • o Classes o o enzymes hormones structure, transport, storage, • o contraction, protection Amino o acids o general structure 20 common amino acids  10 essential amino acids cannot be biosynthesized 21.5 Protein Structure • o  Structural categories o fibrous (linear)  example: collagen • globular example: hemoglobin Levels o o secondary: α-helices, β-pleated sheets o primary: amino acid sequence o tertiary: intramolecular interactions quaternary: subunits

21.6 Nucleic Acids: Blueprints for Proteins • o Basic o nucleotide structure o phosphate sugar: ribose or deoxyribose • o base: purine or pyrimidine Genetic o code o nucleotide o codon gene chromosome

• • • •

• • • • • • •

Chemistry and Medicine: The Essential Amino Acids Figure 21.11 Fibrous and Globular Proteins Figure 21.12 Levels of Protein Structure unnumbered figure: photo of normal and sickled red blood cells Figure Structure of EggFigure 21.13 21.14Primary The α-Helix Structure White Lysozyme

Figure 21.15 The β-Pleated Sheet

Structure Figure 21.16 Interactions within Proteins

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Table 21.2 Protein Functions unnumbered figure: Lewis structures of amino acids Table 21.3 Common Amino Acids Example 21.2 Peptide Bonds

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Figures, Tables, and Solved Examples

Figure 21.17 DNA Structure unnumbered figure: Lewis structures of DNA and RNA bases Figure 21.18 Base Pairing in DNA Figure 21.19 Short Strand of DNA Figure 21.20 Genetic Structure Figure 21.21 Chromosomes

Chapter 21. Biochemistry Teaching Tips

Suggestions and Examples •

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Misconceptions and Pitfalls •

21.5 Protein Structure •

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• Protein structure involves intramolecular interaction between amino acid components that extends far beyond the mere order of the

Protein structural categories arise from different functions.

The fibrous examples like collagen serve as structural elements in muscles for example. Globular proteins are often more water soluble and serve as enzymes or to

support other functions besides structure.

The levels of protein structure arise from the size, complex • structure, and functions of many proteins. The intramolecular interactions often arise from the side chains of the amino acids.

Sickle-cell anemia is due to a protein defect in which a single amino acid is replaced with one that is less functionalized. The ability of the red blood cell to carry oxygen is reduced.

21.6 Nucleic Acids: Blueprints for Proteins •

•

The amino onesessential that cannot be acids are biosynthesized by humans and therefore must be consumed (eaten).

The combination of amino acids to form polypeptides is an example of a condensation reaction. The acid portion of one amino acid combines with the amine portion of another, yielding a peptide bond and a water molecule.

The 20 common amino acids can be placed in a few categories according to their R group: alkyl groups, alcohols and thiols, carboxylic acids, amines and amides, and aromatic rings.

Conceptual Connection 21.1 Peptides

The structures of RNA and DNA are relatively simple considering their importance. For example, only four bases are used to code for a host of proteins. The simple structure, though, enables duplication and repair.

Conceptual Connection 21.2 The Genetic Code

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amino acids in a protein.

• Base-pairing in DNA occurs through specific hydrogen bonding interactions. Basepair mismatches do not have those proper hydrogen bonding interactions.

Chapter 21. Biochemistry Lecture Outline

Terms, Concepts, Relationships, Skills Synthesis • o Replication o DNA double helix structure o o complementary single strands • base-pair match Protein o synthesis o RNA copies of DNA codons ribosomes

• • • • •

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Figures, Tables, and Solved Examples Figure 21.22 Watson and Crick Figure 21.23 DNA Double Helix Figure 21.24 DNA Replication Figure 21.25 Protein Synthesis Chemistry and Medicine: The Human Genome Project

Chapter 21. Biochemistry Teaching Tips

Suggestions and Examples •

•

Misconceptions and Pitfalls

The Human Genome Project has provided the identity and order of bases for all genetic material in humans. Now, the effort is to identify on which chromosome each gene resides and the mechanisms by which the massive amount of information is organized.

Protein synthesis makes use of three-amino-acid codons. As each codon is read by the ribosome, an amino acid is added to the polypeptide.

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Chapter 21. Biochemistry

Additional Problem for Carbohydrates and Optical Isomerism (Example 21.1)

Examine the structure of deoxyribose, part of the backbone in DNA. Does deoxyribose exhibit optical isomerism? If so, which carbon atoms are chiral?

Chiral Centers Examine each carbon to see which have four different atoms or groups attached.

Carbons 3 and 4 are chiral centers. Carbon 1 is the carbonyl C=O; carbon 2 and carbon 5 have two H attached apiece.

Optical Isomerism With two chiral centers, deoxyribose exhibits optical isomerism.

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Chapter 21. Biochemistry

Additional Problem for Peptide Bonds (Example 21.2)

Show the tripeptide that results from linking the amino acids glycine, valine, and serine in that order. Label the N-terminus and C-terminus ends of the tripeptide.

Peptide Bonds A peptide or amide bond forms when the hydroxyl –OH from the carboxylic acid of one amino acid is removed, together with the hydrogen from the amino group of the adjacent amino acid.

Water is removed each time a peptide bond is formed. They appear in the boxes.

Tripeptide The resulting tripeptide is: H2N – glycine – valine – serine – CO2H

307 .

Chapter 22. Chemistry of the Nonmetals Student Objectives

22.1• Insulated Nanowires •

Know that carbon forms nanotubes and that boron nitride, a material that is isoelectronic with carbon, also forms nanotubes.

Know that carbon nanotubes are electrical conductors, while boron nitride nanotubes are electrical insulators.

22.2• The Main-Group Elements: Bonding and Properties Recall the periodic trends for radius, the general properties of metals and nonmetals, and the major divisions of the periodic chart.

22.3• Silicates: The Most Abundant Matter in Earth’s Crust • Define silicate.

• Know that silicon and oxygen together constitute the majority of the earth’s crust.

Know that quartz and glass have the empirical formula SiO2 but consists of tetrahedral SiO4 • • •

Know that aluminosilicates form with Al atoms in Si sites, giving the formula unit AlO−2. structural units.

Know some general characteristics of the different silicate structures.

Predict the structure of a given silicate.

22.4• Boron and Its Remarkable Structures • • Know that the different allotropes of elemental boron, B12, are based on an icosahedral structure. that boron reacts with halogens to form trihalides.

• Know Define and describe the different borane structures: closo, nido, and arachno.

Know that boron reacts with oxygen to form network covalent solids.

22.5• Carbon, Carbides, and Carbonates • theform common crystalline allotropes of carbon: graphite and diamond.

• Describe amorphous of carbon that forms under pressure from the decomposition of Know that coal is an • ancient organic material and consists of three main types: lignite, bituminous, and anthracite.

• Know some general characteristics of coke, charcoal, activated carbon, soot, and carbon black.

Know that carbon also forms fullerenes and nanotubes.

• Know that carbon forms ionic carbides, covalent carbides, and metallic carbides when combined with • different elements.

Know carbon with to oxygen to form carboncarbonic dioxide acid, and carbon monoxide. Know that carbonthat dioxide and combines water combine form the carbonates: bicarbonate, and carbonate.

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Chapter 22. Chemistry of the Nonmetals

22.6• Nitrogen and Phosphorus: Essential Elements for Life • Recall that elemental nitrogen is a diatomic gas that comprises 78% of Earth’s atmosphere.

• Know some general characteristics of the main allotropes of phosphorus: white phosphorus, red • phosphorus, and black phosphorus.

• Know the common nitrogen hydrides: ammonia, hydrazine, and hydrogen azide.

Know the common nitrogen oxides: nitrogen oxide, nitrogen dioxide, dinitrogen trioxide, nitrous • oxide, and dinitrogen tetraoxide.

• • Know the oxyanions and oxyacids of nitrogen: nitrate, nitric acid, and nitrite.

Know that phosphorus forms phosphine (PH3) and the phosphine halides PX3 and PX5.

Know reacts with to form and Know that that phosphorus phosphoric acid and the oxygen phosphates areP4O6 among theP4O10. most important and useful phosphorus compounds.

22.7• Oxygen • • Recall that most elemental oxygen is a diatomic gas that comprises 21% of Earth’s atmosphere.

Know the three oxide types: oxide, peroxide, and superoxide.

Know some general characteristics of another common allotrope of oxygen, ozone (O3).

22.8• Sulfur: A Dangerous but Useful Element • • • • •

Know that elemental sulfur is found in a few natural deposits believed to have been formed by anaerobic bacteria and is extracted by the Frasch process.

Know some general characteristics of dihydrogen sulfide.

Assign oxidation states to sulfur in redox reactions.

Know that sulfur dioxide forms naturally from volcanic activity and forms as a pollutant from coal and oil combustion as well as metal extraction.

Know the most abundantly produced chemical in the world.

Know that somesulfuric generalacid usesisof sulfuric acid.

22.9• Halogens: Reactive Elements with High Electronegativity • • Determine the oxidation states of halogens in redox reactions.

• Know that halogens are not found in their elemental forms because of their high electronegativities.

Know hydrofluoric acid,and andhalogen chlorine.

Know some some general general characteristics characteristics of of fluorine, interhalogen compounds oxides.

Section Summaries

• Outline Lecture • Terms, Relationships, Skills Figures,Concepts, Tables, and Solved Examples • Teaching Tips • Suggestions andand Examples Misconceptions Pitfalls

309 .

Chapter 22. Chemistry of the Nonmetals Lecture Outline

Terms, Concepts, Relationships, Skills • o Carbon nanotubes o o • structure electrical conductivity Boron o nitride nanotubes structure electrical insulation

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22.2 The Main-Group Elements: Bonding and Properties • • • Atomic radius Electronegativity Metals, nonmetals, metalloids

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22.3 Silicates: The Most Abundant Matter in Earth’s Crust • o Quartz o and glass formula unit: SiO2 • • o structure and shape: SiO4 tetrahedra AlO−2 in place of SiO2 Aluminosilicates −44 o Silicate o units, chains, sheets− o orthosilicate: SiO 276 pyrosilicate: SiO unit: SiO−  repeating pyroxene  formula unit: SiO−32 264 o 

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o

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• •

• • • • • • • • •

Predicting structures

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Intro figure: illustration of carbon nanotubes Table 22.1 Properties of BN and C Figure 22.1 Boron Nitride Nanotube

unnumbered figures: periodic tables

• • •

− amphibole repeating and formula unit: 4116 −  SiO phyllosilicate  formula unit: SiO−4104 repeating unit: SiO 252

Figures, Tables, and Solved Examples

Figure 22.2 Major Elements in Earth’s Crust Figure 22.3 SiO4 Tetrahedron Figure 22.4 Structure of Quartz Example 22.1 Determining the Composition of an Aluminosilicate Figure 22.5 Pyrosilicate Structure Figure 22.6 Pyroxene Structure Figure 22.7 Amphibole Structure unnumbered figure: photo of asbestos fibers unnumbered figure: photo of mica sheets Figure 22.8 Phyllosilicate Structure Table 22.2 Types of Silicate Structures Example 22.2 Composition and Charge Balance of Silicates Examples 22.3 and 22.4 Predicting Silicate Structures

Chapter 22. Chemistry of the Nonmetals Teaching Tips

Suggestions and Examples •

Misconceptions and Pitfalls

Nanotubes are modern examples of the descriptive chemistry of carbon, boron, and nitrogen. The microscopic structures are nearly the same, but the macroscopic properties (e.g., electrical conductivity) are different.

22.2 The Main-Group Elements: Bonding and Properties • Review the periodic properties of the p-block elements: electron configurations, electronegativity, radius, electron affinity, and metallic character.

•

22.3 Silicates: The Most Abundant Matter in Earth’s Crust •

Silicates, like SiO2, do not exist as discrete molecules but instead are network covalent solids.

The silicates form a variety of structures, though most of them are based on a tetrahedral shape. This recognizable green pyramid is shown in all of the ball-and-stick models.

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Chapter 22. Chemistry of the Nonmetals Lecture Outline

Terms, Concepts, Relationships, Skills • • • Elemental boron: B12 icosahedron • Boron halides, BX3 o Boron oxygen compounds trigonal BO3 in hexagonal shapes o closo Boron nido o hydrides -boranes o arachno -boranes -boranes 22.5 Carbon, Carbides, and Carbonates • o Crystalline carbon forms o • Coal o graphite: planar, hexagonal o diamond: tetrahedral o lignite bituminous • anthracite • Other types: coke, charcoal, activated carbon, • soot, carbon black o Specialized structures: fullerenes, nanotubes Carbides o ionic o covalent • metallic o Carbon o oxides o • carbon dioxide carbon monoxide Carbonates o o carbonic acid o washing soda baking soda baking powder

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• • • • • • • • • •

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Figures, Tables, and Solved Examples Figure 22.9 B12 Icosahedron Figure 22.11 closo-Borane Structures Figure 22.10 B2O3 Structure Figure 22.12 nido- and arachno-Boranes

Figure 22.13 Graphite Structure Figure 22.14 Diamond Structure Table 22.3 Approximate Composition of the Main Types of Coal unnumbered figure: photo of tires Figure 22.15 C60 and a Geodesic Dome Figure 22.16 Carbon Nanotubes Figure 22.17 The Nanocar Figure 22.18 Calcium Carbide Structure unnumbered figure: micrograph of steel unnumbered figure: photo of Alka-Seltzer tablets in water

Chapter 22. Chemistry of the Nonmetals Teaching Tips

Suggestions and Examples •

Misconceptions and Pitfalls

Boron predominantly forms trigonal structures for boron halide and boron oxide compounds but cage structures for hydride compounds.

•

22.5 Carbon, Carbides, and Carbonates •

• •

•

• •

The crystalline allotropes of carbon are well known; other forms of carbon (e.g., coal, charcoal) are widely used. The newer forms, fullerenes and nanotubes, have been discovered and developed in the last quarter century.

Conceptual Connection 22.1 Phase Changes and Pressure The carbides, particularly the covalent and metallic carbides, are important commercially because of their hardness.

Carbide tips are added to saw blades made of

• •

steel to make them sharper and cut longer.

The combustion products of carbon, CO2 and CO, are well known and highly relevant to daily life.

Conceptual Connection 22.2 Carbonate Solubility Students always are fascinated by the fullerenes and carbon nanotubes.

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Graphite has a high melting point because of the strong bonds within the sheets, but it is slippery because of the weak interactions between graphite sheets.

Large amounts of carbon are sequestered in ocean water, in shells of marine organisms, and in rocks.

Fullerenes, particularly C60 and C70, are naturally occurring.

Chapter 22. Chemistry of the Nonmetals Lecture Outline

Terms, Concepts, Relationships, Skills Life • o nitrogen: N2 (g), 78% of Earth’s Elemental forms o atmosphere   phosphorus  white: P4 tetrahedra red: P4 chains • black: layered like graphite o Nitrogen compounds o hydrides: ammonia, hydrazine, hydrogen azide oxides: nitrogen monoxide, nitrogen o dioxide, dinitrogen trioxide, dinitrogen • o tetraxoxide, nitrous oxide Phosphorus o nitriccompounds acid, nitrate, nitrite o hydride: phosphine o halides: PX3, PX5, POX3 oxides: P4O6, P4O10 phosphoric acid, phosphates

22.7 Oxygen • o Elemental oxygen o o O2 • ozone, O3

• • • • • •

• •

Oxide peroxide: o types oxide: O2−O2−2 superoxide: O−2 o • Ozone o o o strong oxidizing agent disinfectant ozone layer

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Figures, Tables, and Solved Examples Figure 22.19 White Phosphorus Figure 22.20 Red Phosphorus Table 22.4 Oxidation States of Various Nitrogen Compounds Figure 22.21 Hydrazine and Hydrogen Peroxide Figure 22.22 Tetraphosphorus Hexaoxide and Decaoxide, P4O6 and P4O10 Table 22.5 Uses of Phosphates in the Food Industry

unnumbered figure: photo of ocean vents Table 22.6 Types of Oxides

Chapter 22. Chemistry of the Nonmetals Teaching Tips

Suggestions and Examples Life •

•

•

Both extremes of nitrogen fertilizers: the −3 oxidationoxidation state of Nstates in occur in molecules that are important ammonia and the +5 oxidation state ofas N in

A large amount of nitrogen occurs as the elemental gas N2 in the atmosphere. The

•

nitrogen oxides also are gases.

The most common ions containing nitrogen • are nitrate and nitrite. Nitric acid is a strong mineral acid used commercially in the fertilizer industry.

• Ammonia is also a gas. Its natural supply comes from bacteria that are capable of “fixing” nitrogen: cleaving the triple bond in N2.

The allotropes of elemental phosphorus include the P4 tetrahedron of white • phosphorus, the chain forming interconnecting tetrahedra in red phosphorus, and the graphite-like structure of black phosphorus.

Phosphoric acid is used to remove scale (i.e., rust) in the steel industry, in the production of fertilizers, and as a flavorant and preservative in soft drinks. Phosphates are 22.7 Oxygen widely used in detergents and in the food • industry.

•

Misconceptions and Pitfalls

nitrate.

expanded octet because of low-lying dPhosphorus can form molecules with an orbitals.

• Ozone in the upper atmosphere and as a disinfectant is useful, but ground-level ozone is a pollutant.

The atmospheric component gases O2 and O3 are well known, but large quantities of the most common element in Earth’s crust are found as water and oxides of many other elements.

Chemical cycles of bacterial life near some volcanic vents in the ocean are based not on oxygen but on sulfur.

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Chapter 22. Chemistry of the Nonmetals Lecture Outline

Terms, Concepts, Relationships, Skills • o Elemental form o o • isolation by Frasch process oxidation of recycled H2S Hydrogen sulfide o toxicity, odor o o product of bacteria and rotting • different properties from those of H2O Sulfur o dioxide natural volcanic source • combustion product of coal and o petroleum Sulfuric acid o most abundant chemical produced in the world common uses

• • • • •

22.9 Halogens: Reactive Elements with High Electronegativity • o Elemental forms not naturally occurring from oxidation of F− because of o F high electronegativity o 2 o • Cl2 from electrolysis

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• • • •

Interhalogen compounds o ABn A = large, = small for nB = 1, 3, 5, 7(B = F for n = 5, 7) •

•

o Halogen oxides o o often explosive chlorine oxides often strong oxidizing agents

316 .

Figures, Tables, and Solved Examples Figure 22.23 The Frasch Process Figure 22.24 Sulfur Deposits unnumbered figure: photo of molten sulfur Figure 22.25 Quenching Liquid Sulfur Example 22.5 Balancing of and Assigning Oxidation States to Sulfur Reactions Table 22.7 Common Metal Sulfides Figure 22.26 Dehydration of Sucrose

Table 22.8 Selected Properties of the Halogens Example 22.6 Determining the Oxidation State of Halogens in Compounds Table 22.9 Comparison of Halogen X–X Bond Energy Example 22.7 Formation of Interhalogen Compounds Examples 22.8 and 22.9 Molecular Shapes of Interhalogen Compounds Example 22.10 Identifying Changes in Oxidation States

Chapter 22. Chemistry of the Nonmetals Teaching Tips

Suggestions and Examples • 22.8 Sulfur: A Dangerous but Useful Element Elemental sulfur is isolated directly by the Frasch process or by oxidation of H2S that is recycled from other processes. Hydrogen • sulfide is toxic, so it must be removed and/or

•

•

Hydrogen sulfide looks as if it should resemble water based on their formulas.

However, nearly everything about these two compounds, including bond angle, toxicity, and physical properties, is different.

recycled anyway.

Hydrogen sulfide has the characteristic smell of rotting eggs. It can be smelled at about 20 ppb, but the sense of smell is desensitized after exposure.

Sulfur dioxide is an environmental pollutant that arises from combustion of sulfurcontaining coal and petroleum products.

Large quantities of sulfur dioxide also are produced from volcanic activity.

•

22.9 Halogens: Reactive Elements with High Electronegativity • •

Misconceptions and Pitfalls

Like the Group 1A and 2A metals, none of the elemental forms of the halogens occurs naturally because of their high reactivity.

Elemental halogens can be formed by electrolysis of the halide salts.

Halogen oxides are often explosive, and most of the known ones of chlorine are strong oxidizing agents.

317 .

Chapter 22. Chemistry of the Nonmetals

Additional Problem for Predicting Silicate Structures (Examples 22.3, 22.4)

Predict the silicate structure for the mineral talc Mg3Si4O10(OH)2 that serves as the basis for talcum powder, and show that the formula is charge neutral.

Si to O Ratio Determine the ratio of Si to O in the formula.

Si:O ratio is 4:10 or 2:5.

The other two oxygens occur as hydroxides and are not part of the silicate structures. (That situation is indicated by the OH in the parentheses.)

Match Ratio to List Match the Si:O ratio to the type of silicate in Table 22.2.

The 2:5 ratio is indicated for phyllosilicate sheets 2− with a formula unit of Si2O5.

Anion Charge Determine the total anion charge.

SiO2− 25: 2 @ −2 = −4 OH−: 2 @ −1 = −2 total anionic charge = −6

Cation Charge Determine the total cation charge and show that it matches the total anion charge.

Mg2+: 3 @ +2 = +6 total cationic charge = +6 The anionic and cationic charges balance so the formula is charge neutral.

318 .

Chapter 22. Chemistry of the Nonmetals

Calculate the oxidation state for Cl in the compounds:

Additional Problem for Determining the Oxidation State of Halogens in Compounds (Example 22.6)

a) Cl2O6

b) ClF3

c) HClO4

Oxidation states: oxygen: 3 @ −2 = −6 chlorine: 2 @ ?? = +6

Solution a

Chlorine must be +3 oxidation state.

Oxidation states: fluorine: 3 @ −1 = −3 chlorine: 1 @ ?? = +3

Solution b

Chlorine must be +3 oxidation state.

Oxidation states: hydrogen: 1 @ +1 = +1 oxygen: 4 @ −2 = −8 chlorine: 1 @ ?? = +7

Solution c

Chlorine must be +7 oxidation state.

319 .

Chapter 23. Metals and Metallurgy Student Objectives

23.1• Vanadium: A Problem and an Opportunity •

Know petroleum contains vanadium compounds as contaminants at levels that suggest they Definethat metallurgy. were part of some extinct species’ biological systems.

23.2• The General Properties and Natural Distribution of Metals • physical properties of metals.

• Know Know the thatcommon metals make up only about 25% of the Earth’s crust, but Earth’s core is thought to be all •

iron and nickel.

Know homogeneous, inorganic solids.

Know that that minerals an ore is aare rock that containsnaturally-occurring, a high concentrationand of acrystalline specific mineral.

23.3• Metallurgical Processes • • • •

Know metallurgy involves separating the calcination, metal-containing components from the Definethat and extractive describe the main forms of pyrometallurgy: roasting, and smelting. nonmetal-containing components.

Define and describe the process of hydrometallurgy.

Define Define and and describe describe the the process process of of electrometallurgy. powder metallurgy.

23.4• Metal Structures and Alloys • • •

Recall that structures of metals can and be described as the closest packing of spheres into crystal types: Define alloy, substitutional alloy, interstitial alloy. face-centered cubic, body-centered cubic, and hexagonal closest packed.

Determine alloy composition from a binary phase diagram.

23.5 Sources, Properties, andalloys Products of Some of the 3d Transition Metals Describe interstitial in terms of octahedral holes and tetrahedral holes.

• • • • • • •

Describe some general characteristics of titanium Describe some properties and reactions of chromium.

Describe some properties and reactions of manganese.

Describe some characteristics of cobalt.

Describe some characteristics of copper.

Describe some properties of nickel.

Describe some properties of zinc.

320 .

Chapter 23. Metals and Metallurgy

Section Summaries

• Outline Lecture • Terms, Relationships, Skills Figures,Concepts, Tables, and Solved Examples • Teaching Tips • Suggestions andand Examples Misconceptions Pitfalls

321 .

Chapter 23. Metals and Metallurgy Lecture Outline

Terms, Concepts, Relationships, Skills • 23.1 Vanadium: o A Problem and an Opportunity Petroleum contaminants o vanadium compounds • ancient organism biology based on vanadium Metallurgy

• •

23.2 The General Properties and Natural Distribution of Metals • o Properties o o opaque o thermal and electrical conductors malleable • o ductile Distribution o  elemental form: Ni, Cu, Pd, Ag, Pt, Au  minerals and ores  chloride minerals oxide minerals sulfide minerals 23.3 Metallurgical Processes • o Isolation steps o o mining • separation o refining  Extractive metallurgy  Pyrometallurgy  calcination  roasting  smelting flux o  slag o hydrometallurgy  leaching electrometallurgy  aluminum: Hall process o copper powder metallurgy

• • •

• • • • •

322 .

Figures, Tables, and Solved Examples Intro figure: illustration of a fossil unnumbered figure: photo of vanadium

Table 23.1 Thermal Conductivity and Electrical Resistivity of Several Metals unnumbered figure: photo of gold unnumbered figure: photo of NaCl basins

Figure 23.1 Separation by Air Figure 23.2 Separation by Using a Solution Figure 23.3 The Hall Process unnumbered figure: photo of machined metal products Figure 23.4 Copper Electrolysis Cell

Chapter 23. Metals and Metallurgy Teaching Tips

Suggestions and Examples •

•

Misconceptions and Pitfalls Vanadium may only be present in trace quantities, but the process of converting petroleum to fuel products or burning the fuels may concentrate the samples.

The vanadium story is an interesting one since it requires some higher-order thinking skills.

One might ask, “What else is in oil, and how did it get there?” The same question also is valid for coal. For example, uranium in coal occurs at levels between 1 and 10 ppm, and mercury in coal occurs at levels between 70 and 200 ppb.

These may seem small unless one realizes that a large power plant under full load may burn tons of coal per 23.2 The10,000 General Properties andday.

Natural Distribution of Metals • Understanding the distribution of metals in nature requires knowledge of the structure and composition of ores and minerals. Most metallurgy has to deal with huge quantities of ores to generate a limited amount of metal, making cost effectiveness a challenge. For many metals, recycling is appropriate. This is especially true for aluminum and copper that use expensive electricity in electrolysis.

•

23.3 Metallurgical Processes • Metallurgical processes have been developed over time to make the isolation of metals more efficient. The technique used for a particular metal is likely to depend on the nature and quantity of an elemental metal or its ore. Gold occurs as a metal but in small enough particles that leaching it is justified, in part, because of its great value. The reduction of iron in an ore is accomplished by a redox reaction in which carbon is burned with the ore, forming iron metal and carbon dioxide. On the other hand, the oxidation potential of carbon is not sufficient to effect the same transformation in aluminum. Reduction of Al3+ requires the more costly electrolysis.

323 .

Metallurgy takes advantage of basic chemical principles to concentrate an element or mineral or to reduce metal cations to the elemental form.

Chapter 23. Metals and Metallurgy Lecture Outline

Terms, Concepts, Relationships, Skills • o Closest o packing of spheres o face-centered cubic body-centered cubic • Alloys ohexagonal closest packed   substitutional  miscible solid solutions  alloys with limited solubility o phase diagrams and examples  interstitial octahedral holes tetrahedral holes

• •

• • • • •

• • • •

23.5 Sources, Properties, and Products of Some of the 3d Transition Metals • o Titanium • sources (ores, minerals); uses; o reactions Chromium • sources (ores, minerals); uses; alloys; o reactions Manganese • sources (ores, minerals); uses; alloys; Cobalt oreactions sources (ores, minerals); uses • (magnetic materials) o Copper • sources (elemental form, ores, Nickel ominerals); uses; alloys (brass) • Zinc o sources; uses; alloys sources (ores, minerals); uses; alloys 324 .

Figures, Tables, and Solved Examples 3d Elements Table 23.2 The Crystal Structures of the unnumbered figure: illustrations of copper, nickel-copper-alloy crystal structures Figure 23.5 Cu-Ni Phase Diagram Examples 23.1 and 23.2 Determining Alloy Compositions from a Phase Diagram Figure 23.6 Cr-V Phase Diagram Figure 23.7 Cr-Ni Phase Diagram Examples 23.3 and 23.4 Alloy Compositions in a Solid Solution with Limited Solubility Figure 23.8 Octahedral Holes in Closest Packed Crystals Figure 23.9 A Different View of an Octahedral Hole Figure 23.10 A Tetrahedral Hole in a Closest Packed Crystal Table 23.3 Formulas of Several Interstitial Alloys

• • • • • • •

Figure 23.11 Chromium Compounds Table 23.4 The Colors of Various Chromium Compounds unnumbered figure: ball-and-stick models of chromate and dichromate unnumbered figure: combustion of ammonium dichromate unnumbered figure: photo of power poles and lines unnumbered figure: photos of uses of copper unnumbered figure: photo of zinc phosphate on steel

Chapter 23. Metals and Metallurgy Teaching Tips

Suggestions and Examples •

•

•

Misconceptions and Pitfalls The formulation of alloys takes advantage of knowledge of both the microscopic properties (crystal forms, sizes of component metals) and macroscopic properties (melting points and phase diagrams).

Knowledge of crystal lattices takes on a practical application at this stage.

Understanding substitutional alloys requires knowledge of the size of a potential component and melting information as a function of the mole percent of the components. Interstitial alloys can take advantage of the holes in closest packed crystals, both octahedral and tetrahedral holes that are determined by the number of

neighboring atoms.

Conceptual Connection 23.1 Interstitial Alloys Ask the students to answer to same question from Conceptual Connection 23.1 for the case of octahedral holes. What fraction of octahedral holes would need to be filled to get the same ratio of metals as was obtained for the tetrahedral holes?

23.5 Sources, Properties, and Products of Some of the 3d Transition Metals • •

Case studies of seven metals are outlined.

They compare and contrast sources, method of metal isolation, and practical applications or uses of the metal and some of its compounds. Important and interesting examples have been selected in preference to marching through all the groups.

325 .

Chapter 24. Transition Metals and Coordination Compounds Student Objectives

that colors gemstones are attributable to electronic transitions between the d-orbitals of 24.1• TheKnow Colors of the Rubies andofEmeralds transition elements.

Recall that the transition metals occupy the d block of the periodic table.

24.2• Properties of Transition Metals • Recall how to write electron configurations and determine oxidation states for d-block elements.

• Recall trends in radius, ionization energy, and electronegativity for d-block elements.

Define complex ion, ligand, coordination compound, and coordinate covalent bond.

24.3• Coordination Compounds • • Define chelate and chelating agent.

• Recognize monodentate, bidentate, and polydentate ligands.

• Recognize the common geometries of complex ions.

Write names and formulas for coordination compounds.

24.4• Structure and Isomerization • • Differentiate between structural isomers and stereoisomers.

• Recognize and identify coordination isomers and linkage isomers.

Identify and draw geometric isomers.

Recognize and draw optical isomers.

24.5• Bonding in Coordination Compounds • Explain the crystal field theory of d-orbital splitting in octahedral and tetrahedral complexes.

• State the hybridization of the metal center using valence bond theory for particular geometries.

Understand the relationship between crystal field splitting and the colors of transition metal • • • •

complexes.

Know between weak-field, moderate-field, andmagnetic strong-field ligands. of transition metal Know the the difference relationship between crystal field splitting and the properties complexes.

Understand the difference between high-spin low-spincomplex. in transition metal complexes.

Predict the number of unpaired electrons in anand octahedral

24.6• Applications of Coordination Compounds • Know the role of transition metals in biomolecules such as hemoglobin, cytochrome c, chlorophyll, Know that EDTA is used as a chelating agent to bind toxic heavy metals. and carbonic anhydrase.

326 .

Chapter 24. Transition Metals and Coordination Compounds Section Summaries

• Outline Lecture • Terms, Relationships, Skills Figures,Concepts, Tables, and Solved Examples • Teaching Tips • Suggestions andand Examples Misconceptions Pitfalls

327 .

Chapter 24. Transition Metals and Coordination Compounds Lecture Outline

Terms, Concepts, Relationships, Skills • • Crystal field Cr3+ o in Al2O3 (ruby, red) o • in Be3Al2(SiO3)6 (emerald, green) in garnet (red) Fe2+ o in peridot (yellow-green) o Cu2+ o • in turquoise

• Figures, Tables, and Solved Examples

24.2 Properties of Transition Metals • • Electron configurations o Periodic properties o o atomic radius • first ionization energy electronegativity Oxidation states

•

24.3 Coordination Compounds • • o Coordination complex o complex ion plus counterions Common ligands monodentate: water, ammonia, o chloride, carbon monoxide,

•

o •

•

the shape of the dz2orbital

Intro figure: illustration of ruby color and

•

unnumbered figure: photos of ruby, emerald, garnet, peridot, turquoise

• • • • •

• • • • •

thiocyanate bidentate: oxalate, ethylenediamine polydentate: ethylenediamine

•

o tetraacetate Geometries and coordination number o o linear o square planar tetrahedral Names ooctahedral ligands and prefixes o metal center o names of metals in anionic complexes

•

328 .

Table 24.1 First-Row Transition Metal Orbital Occupancy Examples 24.1 and 24.2 Writing Electron Configurations for Transition Metals Figure 24.1 Trends in Atomic Radius Figure 24.2 Trends in First Ionization Energy Figure 24.3 Trends in Electronegativity Figure 24.4 First-Row Transition Metal Oxidation States

unnumbered figure: molecular model of [Co(NH3)6]Cl3 Table 24.2 Common Ligands Figure 24.5 Bidentate and Polydentate Ligands Coordinated to Co(III) Table 24.3 Common Geometries of Complex Ions unnumbered table: Guidelines for Naming Complex Ions Table 24.4 Names and Formulas of Common Ligands Table 24.5 Names of Common Metals when Found in Anionic Complex Ions Examples 24.3 and 24.4 Naming Coordination Compounds

Chapter 24. Transition Metals and Coordination Compounds Teaching Tips

Suggestions and Examples •

Misconceptions and Pitfalls

The colors of gemstones due to transition metals in different mineral environments are an introduction to crystal field theory, coordination compounds, and complex ions.

•

24.2 Properties of Transition Metals •

• •

The electron configurations of transition metals follow the rules and guidelines set

•

forth previously in Section 8.4.

Conceptual Connection 24.1 Size Oxidation states are likely toAtomic be somewhat

confusing because of the variety of values some elements can assume. In general, the first-row transition metals can have oxidation states of +2 and +3. Elements in the center of the row have more possible states than the ones on the ends. For example, Sc is only +3, Zn is only +2, but Mn 24.3 Coordination Compounds • can be any state from +2 to +7.

•

•

transition metals fill the 4s before the 3d Electron thebefirst-row unless allconfigurations the 3d orbitalsofcan filled evenly (e.g., Cr and Cu).

remove electrons from the 4s before the 3d.

When forming cations of transition metals,

• the metal are found in the d-orbitals. For this In complexes, all of the valence electrons on reason, complexes of Ir+ are isoelectronic with complexes of Pt2+ and Au3+.

Students may be confused about the organization of metal cations, ligands, and additional properties for complex ions. Table 24.2 lists the common ligands, and Table 24.3 lists the shapes and coordination numbers.

Likewise, one can often predict the geometry given the formula of a complex ion.

Students may struggle predicting the formulas of complex ions. For example, what does Fe2+ form when reacted with ammonia?

Naming complex ions follows some basic guidelines. Often, coordination chemistry relies more on structures than on names.

329 .

Chapter 24. Transition Metals and Coordination Compounds Lecture Outline

Terms, Concepts, Relationships, Skills • o Structural isomers o o • coordination isomers linkage isomers Stereoisomers  cis -trans geometric isomers  fac-mer o

•Figures, Tables, and Solved Examples • • Figure 24.6 Types of Isomers 24.7Ligands LinkageCapable Isomersof Linkage • Figure Table 24.6 • Isomerization • Figure 24.8 Cis-trans Isomerism Figure 24.9 Fac-Mer Isomerism in • Co(NH3)3Cl3 Examples 24.5 and 24.6 Identifying and • Drawing Geometric Isomers Figure 24.10 Optical Isomerism in [Co(en)3]3+ Example 24.7 Recognizing and Drawing Optical Isomers

optical isomers

•

24.5•Bonding in Coordination Compounds o Valence o bond theory o geometry hybridization • o orbitals Crystal field theory o d  orbital orientation  octahedral field  splitting pattern  strong field field  weak colors and crystal field  splitting energy

o o

•

• • • • • • •

spectrochemical series   magnetism high-spin low-spin  tetrahedral field  splitting pattern square planar field splitting pattern

• •

330 .

Figure 24.11 Hybridization 24.12 Common Relative Positions of d Schemes in Complex Ions Orbitals and Ligands in an Octahedral Figure 24.13 d Orbital Splitting in an Complex Octahedral Field Figure 24.14 Colors of Complex Ions Figure 24.15 The Color Wheel Figure 24.16 The Color and Absorption Spectrum of [Ti(H2O)6]3+ Example 24.8 Crystal Field Splitting Energy unnumbered figures: orbital diagrams of low- and high-spin Fe2+ complexes Examples 24.9 and 24.10 High- and LowFigure 24.17 Splitting of d Orbitals by a Spin Octahedral Complexes Figure 24.18 Splitting of d Orbitals by a Tetrahedral Ligand Geometry Square Planar Ligand Geometry

Chapter 24. Transition Metals and Coordination Compounds Teaching Tips

Suggestions and Examples • • Some ligands can be attached in two distinct ways, giving rise to linkage isomers.

Models are likely to be very helpful for seeing • Fac and mer require three ligands of the or visualizing the arrangement of the ligands in octahedral structures.

• same kind in an octahedron.

Visualizing optical isomerism in octahedral complexes is much more difficult than in tetrahedral complexes. Models are essential for the beginning student.

•

24.5 Bonding in Coordination Compounds •

•

•

•

•

Misconceptions Pitfalls Tetrahedral complexesand cannot exhibit cisisomerism, and square planar complexes cannot exhibit optical isomerism.

The crystal field model is completely electrostatic and views all ligands as merely point negative charges. This model does not explain the spectrochemical series at all.

Strong- and weak-field effects of ligands can be confirmed by the number of unpaired

•

electrons in octahedral complexes.

Demonstrations of color (especially cobalt complexes) and magnetism (diamagnetism, paramagnetism, and number of unpaired electrons) are easy and highly illustrative.

Conceptual Connection 24.2 Weak- and Strong-Field Ligands

331 .

Students often will simply memorize the splitting patterns for octahedral, tetrahedral, and square planar complexes. considering the orientation of These the d orbitals patterns can be simply deduced by and the positions of the incoming ligands.

Students often confuse the terms weak- and strong-field with high- and low-spin.

Chapter 24. Transition Metals and Coordination Compounds Lecture Outline

Terms, Concepts, Relationships, Skills • • Chemical analysis: SCN− • Chelating agents: EDTA • Coloring agents and cytochrome c: iron in o hemoglobin Biomolecules o porphyrin ligand o o • chlorophyll: magnesium in porphyrin carbonic anhydrase: zinc Drugs and therapeutic agents cisplatin: cis-[Pt(NH3)2Cl2]

and Solved Examples FigureTables, 24.19 Chemical Analysis with SCN− • Figures, • Table 24.7 Transition Metals and Some of Their Functions in the Human Body • cytochrome c, heme • unnumbered figure: structures of Figure 24.20 Porphyrin • Figure 24.21 Hemoglobin • Figure 24.22 Chlorophyll • Figure 24.23 Carbonic Anhydrase • Figure 24.24 Cisplatin

332 .

Chapter 24. Transition Metals and Coordination Compounds Teaching Tips

Suggestions and Examples •

Misconceptions and Pitfalls

The use of chelating agents to remove lead and mercury is a documented treatment when a case of heavy metal poisoning is known or strongly suspected. With an unsubstantiated belief that mercury-containing preservatives found in a few antiviral vaccines cause autism, some children are being subjected to EDTA treatment. What are some of the potential dangers or hazards of chelation therapy?

333 .

Chapter 24. Transition Metals and Coordination Compounds

Additional Problem for Writing Electron Configurations for Transition Metals (Examples 24.1, 24.2)

Write the ground state electron configuration for Nb and Nb3+.

Identify noble gas Identify the noble gas that precedes the element and put it in square brackets.

Nb is atomic number 41 in=period Complete noble gas shell [Kr] 5 and group 5B.

Count the periods Count down the periods to determine the outer principal quantum level—this is the quantum level for the s orbital. Subtract one to obtain the quantum level for the d orbital.

Nb is in the 5th period: [Kr] 5s4d

Count electrons Count across the row to see how many electrons are in the neutral atom and fill the orbitals accordingly.

For an ion, remove the required number of electrons, first from the s and then from the d orbitals.

Nb has 5 more electrons than [Kr]: [Kr] 5s24d3 Nb3+ has lost three electrons relative to Nb: [Kr] 5s04d2 or [Kr] 4d2

334 .

Chapter 24. Transition Metals and Coordination Compounds

How many unpaired electrons would you expect for 2+ the complex ion [Cu(NH3)6]?

Additional Problem for High- and Low-Spin Octahedral Complexes (Example 24.9, 24.10) Charge and number of d electrons Begin by determining the charge and number of d electrons on the metal.

complex ion = +2 NH3: 6 @ +0 = 0 Cu: 1 @ +2 = +2  Cu2+ Cu: [Ar] 4s13d10 Cu2+: [Ar] 4s03d9  Cu2+ has d9 configuration.

Ligands in spectrochemical series Look at the spectrochemical series to determine whether the ligand is a strong-field or weak-field ligand.

NH3 is a strong-field ligand, so ∆ will be relatively large.

High-spin or low-spin?

Decide if the complex will be high- or low-spin and draw the electron configuration.

Strong-field ligands yield low-spin configurations.

Unpaired electrons Count the unpaired electrons.

This configuration has one unpaired electron.

335 .