St. George's College
Subject: 8th CHEMISTRY
Groups and Periods
Date: June 9th
Link and Learn
8th Milton A ‐ Valence Electrons Name
Sergio María Fernanda Alejandra Almendra Anna Paula Sandra E‐C Maia María Belén Alfredo Kinley Arianne Sandra M. Fiorella Rodrigo Giulia Jaime Stefano Bruno
8th Milton Alpha ‐ Valence Electrons Name
Marcelo Antonella Paulo Alejandro Brenda Diego Gabriel Valeria Cristina Giuliana Joshua María Gracia Gonzalo N. Paolo Gonzalo R. Giorgio Nicolás María Claudia
Let's remember previous learned concepts...
Columns are called Groups • Each vertical column of elements (from top to bottom) on the periodic table is called a Group. • Elements in the same group often have similar chemical and physical properties . • For this reason, a group is also called a family.
Classes of Elements • Elements are classified as metals, nonmetals, and metalloids (poor metals), according to their properties. • The number of electrons (e‐) in the last energy level of an atom is one characteristic that helps determine which category an element belongs in. • The zigzag line in the table determines which elements are metals, nonmetals and metalloids.
New knowledge beginning......
Grouping the Elements • The properties of the elements in a group are similar because the atoms of the elements have the same number of electrons in their outer energy level. • Atoms give, take or share electrons with other atoms in order to have a complete set of electrons in their outer energy level. • Those elements are called reactive and can combine to form compounds.
Group 1: Alkali Metals Group IA
• Group contains: Metals • Electrons in outer level: 1 • Reactivity: Very reactive • Shared properties: softness, silver color, shininess, low density
• Alkali Metals are the most reactive metals because their atoms can easily give away the one outerlevel electron. • Pure alkali metals are stored in oil, to keep them from reacting with oxygen or water in the air. • Alkali metals are so reactive that in nature they’re only found forming compounds with other elements.
Group 2: Alkali‐Earth Metals
• Group contains: Metals • Electrons in outer level: 2 • Reactivity: Very reactive (but less than Alkali Metals) • Shared properties: silver color, higher densities than alkali metals.
• Atoms of alkali‐earth metals have 2 electrons in the outer energy level, which makes it more difficult for these atoms to give two electrons instead of just one.
Groups 3 ‐ 12: Transition Metals
• Group contains: Metals • Electrons in outer level: 1 or 2 • Reactivity: Less than Alkali‐Earth Metals • Shared properties: shininess, good conductors of thermal energy and electric current, higher densities and melting points than elements from groups 1 and 2 (except Hg).
• Groups 3 – 12 do not have individual names. Instead, they’re all called transition metals. • These elements do not give away their electrons easily, making them less reactive than groups 1 and 2.
Lanthanides and Actinides • Some transition metals from periods 6 and 7 appear in two rows at the bottom of the periodic table to keep it from being too wide. • The elements in each row tend to have similar properties. • Elements in the first row follow Lanthanum and are called Lanthanides (shiny, reactive metals). • Elements in the second row follow Actinium, and are called Actinides (radioactive or unstable) • Elements after Plutonium 94, are artificially made in laboratories.
Group 13: Boron Group Group IIIA
• • • •
Group contains: One metalloid and 4 metals. Electrons in outer level: 3 Reactivity: Reactive Shared properties: solids at room temperature.
• Aluminum is the most common element of this group, and the most abundant metal in the Earth’s crust.
Group 14: Carbon Group Group IVA
• • • •
Group contains: One nonmetal and 2 metals. Electrons in outer level: 4 Reactivity: Varies among the elements. Shared properties: solids at room temperature.
• Carbon can be found uncombined in nature, but can also form a wide variety of compounds (carbohydrates, fats, proteins, etc). • Germanium and Silicon are used to make computer chips. • The Tin metal is a metal that is not very reactive, which makes it useful to coat other metals to prevent them from rusting.
Group 15: Nitrogen Group Group VA
• Group contains: Two nonmetals, two metalloids and one metal. • Electrons in outer level: 5 • Reactivity: Varies among the elements. • Shared properties: solids at room temperature (except N).
• Nitrogen, which is a gas at room temperature, makes up about 80% of the air you breathe. • Nitrogen from air can be reacted with Hydrogen to make ammonia for fertilizers. • Although Nitrogen is not very reactive, Phosphorus is extremely reactive (to the point that it can only be found forming compounds in nature).
Group 16: Oxygen Group Group VIA
• Group contains: Three nonmetals, one metalloid and one metal. • Electrons in outer level: 6 • Reactivity: Reactive. • Shared properties: solids at room temperature (except O).
• Oxygen makes up about 20% of air, and it is necessary for substances to burn, and to living organisms to obtain energy. • Sulfur is another common element of this group, found as a yellow solid in nature.
Group 17: Halogens Group Group VIIA
• Group contains: Three nonmetals, one metalloid and one metal. • Electrons in outer level: 7 • Reactivity: Reactive. • Shared properties: poor conductors of electric current, violent reaction with alkali metals to form salts, never in uncombined form in nature.
• Halogens are very reactive nonmetals because their atoms need to gain only one electron to have a complete set of electrons in the outer energy level. • Usually reacting with metals to obtain that missing electron, producing a salt. • Halogens have similar chemical properties but very different physical properties.
Group 18: Noble Gases Group VIIIA
• Group contains: Nonmetals. • Electrons in outer level: 8 (except Helium, with only 2). • Reactivity: Non‐Reactive. • Shared properties: Colorless, odorless gases at room temperature.
• Noble Gases are unreactive nonmetals because their atoms have a complete set of electrons in their outer energy level. • Under normal conditions they do not react with other elements. • This non‐reactivity makes them useful (light bulbs last longer when filled with Argon).
• Electrons in outer level: 1. • Reactivity: Reactive. • Shared properties: Colorless, odorless gas at room temperature, low density, explosive reactions with oxygen.
• Hydrogen’s properties do not match any single group, so it is set apart from the other elements in the table. • Hydrogen is above group 1 because atoms of the alkali metals also have only one electron in their outer energy level. • Its physical properties are more like those of nonmetals than those of metals. So Hydrogen makes a group of its own.
Resources Used Slide (Group)
G1 ‐ 2
G1 ‐ 3
G1 ‐ 4 Image G1 ‐ 7
G1 ‐ 9 Image
IS Units and Prefixes http://tinyurl.com/c9d69c Mendeleev
G1 ‐ 10 G1 ‐ 12 G1 ‐ 14
Teacher's Notes This class has been designed to cover the topics of Groups and Periods from Monday June 8th till Friday June 12th. For further knowledge about this topic: 1. Conduct a thorough search under the topic: Groups and Periods on the Web, books and magazines. 2. If findings are not specific, ask your teacher for suggestions.
Objectives • Identify and describe the characteristics of Groups and Periods in the periodic table. • Describe the members of the main groups and periods in the periodic table.
Note: All, or most, of the objectives will be covered during class time, however the student must be responsible for those objectives not covered or concluded.
Vocabulary • • • • •
Element: Atomic Number: Atomic Mass: Group: Period:
Note: Most of the vocabulary words will be covered during class time, however the student must be responsible for those words not covered or concluded.
Link and Learn You can visit the following websites to improve your understanding on the present topic: • • • • •
http://www.chem1.com/acad/webtext/atoms/atpt‐6.html#SIZE http://www.dayah.com/periodic/ http://science‐learning2009.wikispaces.com http://learningandscience.blogspot.com http://libraryatstgeorge.blogspot.com
Gerardo LAZARO Science Lead Teacher Email: firstname.lastname@example.org Wiki: http://science‐learning.wikispaces.com Blog: http://learningandscience.blogspot.com Twitter: http://twitter.com/glazaro