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AQA GCSE (9–1)

Chemistry Student Book

Ann Daniels Series editor: Ed Walsh

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You can use this book if you are studying Combined Science: Trilogy

Contents

you will need to master all of the ideas and concepts on these pages you will need to master some of the ideas and concepts on these pages.

How to use this book 

6

Chapter 1  Atomic structure and the periodic table12

1.1

Elements and compounds Atoms, formulae and equations 1.3 Mixtures 1.4 Changing ideas about atoms 1.5 Modelling the atom 1.6 Relating charges and masses 1.7 Sub-atomic particles 1.8 Electronic structure 1.9 The periodic table 1.10 Developing the periodic table 1.11 Comparing metals and non-metals 1.12 Metals and non-metals 1.13 Key concept: The outer electrons 1.14 Exploring Group 0 1.15 Exploring Group 1 1.16 Exploring Group 7 1.17 Reaction trends and predicting reactions 1.18 Transition metals 1.19 Maths skills: Standard form and making estimates 1.2

14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Chapter 2  Structure, bonding and the properties of matter56

2.1

Chemical bonds Ionic bonding 2.3 Ionic compounds 2.4 Covalent bonding 2.5 Metallic bonding 2.6 Three states of matter 2.7 Properties of ionic compounds 2.8 Properties of small molecules 2.9 Polymer structures 2.10 Giant covalent structures 2.11 Properties of metals and alloys 2.12 Diamond 2.13 Graphite 2.14 Graphene and fullerenes 2.15 Nanoparticles, their properties and uses 2.16 Key concept: Sizes of particles and orders of magnitude 2.17 Maths skills: Visualise and represent 2D and 3D shapes 2.2

58 60 62 64 66 68 70 72 74 76 78 80 82 84 86

90

Key concept: Conservation of mass and balanced equations 3.2 Relative formula mass 3.1

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98 100

102 104 106 108 110 112 114 116 118 120 122 124

Chapter 4  Chemical changes130

88

Chapter 3  Chemical quantities and calculations96

3.3 Mass changes when gases are in reactions 3.4 Chemical measurements and uncertainty 3.5 Moles 3.6 Amounts of substances in equations 3.7 Using moles to balance equations 3.8 Concentration of solutions 3.9 Key concept: Percentage yield 3.10 Atom economy 3.11 Using concentrations of solutions 3.12 Amounts of substance in volumes of gases 3.13 Key concept: Amounts in Chemistry 3.14 Maths skills: Change the subject of an equation Metal oxides Reactivity series 4.3 Extraction of metals 4.4 Oxidation and reduction in terms of electrons 4.5 Reaction of metals with acids 4.6 Neutralisation of acids and salt production 4.7 Soluble salts 4.8 Required practical: Preparing a pure, dry sample of a soluble salt from an insoluble oxide or carbonate 4.9 pH and neutralisation 4.10 Required practical: Finding the reacting volumes of solutions of acid and alkali by titration 4.11 Strong and weak acids 4.12 The process of electrolysis 4.13 Electrolysis of molten ionic compounds 4.14 Using electrolysis to extract metals 4.15 Electrolysis of aqueous solutions 4.16 Required practical: Investigating what happens when aqueous solutions are electrolysed using inert electrodes 4.17 Key concept: Electron transfer, oxidation and reduction 4.18 Maths skills: Make order of magnitude calculations 4.1

4.2

132 134 136 138 140 142 144

146 148

150 152 154 156 158 160

162 164 166

Chapter 5  Energy changes172

Key concept: Endothermic and exothermic reactions 174 5.2 Required practical: Investigate the variables that affect temperature changes in reacting solutions such as, acid plus metals, acid plus carbonates, neutralisations, displacement of metals 176 5.1

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5.3 5.4 5.5 5.6 5.7

Reaction profiles Energy change of reactions Cells and batteries Fuel cells Maths skills: Recognise and use expressions in decimal form

178 180 182 184 186

Chapter 6  The rate and extent of chemical change192

6.1 6.2 6.3 6.4 6.5

6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 6.14

Measuring rates 194 Key concept: Limiting reactants and molar masses 196 Calculating rates 198 Factors affecting rates 200 Required practical: Investigate how changes in concentration affect the rates of reactions by a method involving the production of gas and a method involving a colour change 202 Factors increasing the rate 204 Collision theory 206 Catalysts 208 Reversible reactions and energy changes 210 Equilibrium 212 Changing concentration and equilibrium 214 Changing temperature and equilibrium 216 Changing pressure and equilibrium 218 Maths skills: Use the slope of a tangent as a measure of rate of change 220

Chapter 7  Hydrocarbons

226

228

7.1

Crude oil, hydrocarbons and alkanes Fractional distillation and petrochemicals 7.3 Properties of hydrocarbons 7.4 Combustion 7.5 Cracking and alkenes 7.6 Structure and formulae of alkenes 7.7 Reactions of alkenes 7.8 Alcohols 7.9 Carboxylic acids 7.10 Addition polymerisation 7.11 Condensation polymerisation 7.12 Amino acids 7.13 DNA and other naturally occurring polymers 7.14 Key concept: Intermolecular forces 7.15 Maths skills: Visualise and represent 3D models

252 254 256

Chapter 8  Chemical analysis

262

264 266 268

Key concept: Pure substances 8.2 Formulations 8.3 Chromatography 8.1

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270 272 274 276 278

280 282 284 286

Chapter 9  The atmosphere

292

294 296 298 300 302 304 306 308

7.2

230 232 234 236 238 240 242 244 246 248 250

Required practical: Investigate how paper chromatography can be used in forensic science to identify an ink mixture used in a forgery 8.5 Test for gases 8.6 Flame test 8.7 Metal hydroxides 8.8 Test for anions 8.9 Required practical: Use chemical tests to identify the ions in unknown single ionic compounds 8.10 Instrumental methods 8.11 Flame emission spectroscopy 8.12 Maths skills: Use an appropriate number of significant figures 8.4

9.1

Proportions of gases in the atmosphere The Earth’s early atmosphere 9.3 How oxygen increased 9.4 How carbon dioxide decreased 9.5 Key concept: Greenhouse gases 9.6 Human activities 9.7 Global climate change 9.8 Carbon footprint and its reduction 9.9 Limitations on carbon footprint reduction 9.10 Atmospheric pollutants from fuels 9.11 Properties and effects of atmospheric pollutants 9.12 Maths skills: Use ratios, fractions and percentages 9.2

310 312 314 316

Chapter 10  Sustainable development322

Key concept: Using the Earth’s resources and sustainable development 324 10.2 Potable water 326 10.3 Required practical: Analysis and purification of water samples from different sources, including pH, dissolved solids and distillation 328 10.4 Waste water treatment 330 10.5 Alternative methods of metal extraction 332 10.6 Life cycle assessment and recycling 334 10.7 Ways of reducing the use of resources 336 10.8 Corrosion and its prevention 338 10.9 Alloys as useful materials 340 10.10 Ceramics, polymers and composites 342 10.11 Haber process 344 10.12 Production and use of NPK fertilisers 346 Maths skills: Translate information 10.13 between graphical and numerical form 348 10.1

Glossary355 Index361

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Chemistry

ELEMENTS, MIXTURES AND COMPOUNDS s¬ MIXTURES¬CAN¬BE¬SEPARATED¬EASILY¬BY¬l¬LTERING¬AND¬OTHER¬ WAYS s¬ %LEMENTS¬CANNOT¬BE¬BROKEN¬DOWN¬BY¬CHEMICAL¬MEANS s¬ #OMPOUNDS¬ARE¬MADE¬FROM¬ELEMENTS¬CHEMICALLY¬COMBINED

ATOMS AND THEIR STRUCTURE s¬ %LECTRONS¬HAVE¬A¬NEGATIVE¬CHARGE¬ s¬ !TOMS¬HAVE¬A¬NUCLEUS¬WITH¬A¬POSITIVE¬CHARGE s¬ %LECTRONS¬ORBIT¬THE¬NUCLEUS¬IN¬SHELLS

SOME ELEMENTS AND THEIR COMPOUNDS s¬ (ELIUM¬IS¬UNREACTIVE¬AND¬USED¬IN¬BALLOONS s¬ 3ODIUM¬CHLORIDE¬IS¬USED¬TO¬m¬AVOUR¬AND¬PRESERVE¬FOOD¬ s¬ #HLORINE¬IS¬USED¬TO¬KILL¬BACTERIA¬IN¬SWIMMING¬POOLS

METALS IN THE PERIODIC TABLE s¬ 'OLD ¬SILVER¬AND¬PLATINUM¬ARE¬PRECIOUS¬METALS¬ s¬ -ERCURY¬IS¬A¬LIQUID¬METAL s¬ :INC ¬COPPER¬AND¬IRON¬ARE¬USED¬TO¬MAKE¬MANY¬USEFUL¬ OBJECTS

METALS AND NON-METALS s¬ 'OLD ¬IRON ¬COPPER¬AND¬LEAD¬ARE¬METALS¬KNOWN¬FOR¬ CENTURIES s¬ /XYGEN¬AND¬NITROGEN¬ARE¬GASES¬OF¬THE¬AIR s¬ 3ULFUR¬IS¬A¬YELLOW¬NON METAL

12

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WHAT MODEL DO WE USE TO REPRESENT AN ATOM? s¬ %LECTRONS¬l¬LL¬THE¬SHELLS¬AROUND¬THE¬NUCLEUS¬IN¬SET¬PATTERN¬ ORDERS¬ s¬ 0ROTONS¬AND¬NEUTRONS¬MAKE¬UP¬THE¬NUCLEUS s¬ %LECTRONS¬CAN¬BE¬LOST¬FROM¬OR¬GAINED¬INTO¬THE¬OUTER¬SHELL

HOW DID THE MODEL OF THE ATOM DEVELOP? s¬ !TOMS¬USED¬TO¬BE¬THOUGHT¬OF¬AS¬SMALL¬UNBREAKABLE¬SPHERES s¬ %XPERIMENTS¬LED¬TO¬IDEAS¬OF¬ATOMS¬WITH¬A¬NUCLEUS¬AND¬ ELECTRONS s¬ %LECTRONS¬IN¬SHELLS¬AND¬THE¬DISCOVERY¬OF¬THE¬NEUTRON¬CAME¬LATER

WHY CAN WE USE CARBON DATING? s¬ !TOMS¬OF¬AN¬ELEMENT¬ALWAYS¬HAVE¬THE¬SAME¬NUMBER¬OF¬ PROTONS s¬ 4HEY¬DO¬NOT¬ALWAYS¬HAVE¬THE¬SAME¬NUMBERS¬OF¬NEUTRONS s¬ %LEMENTS¬EXIST¬AS¬DIFFERENT¬ISOTOPES

C

C

Spot the difference in these isotopes

WHY IS HELIUM SO UNREACTIVE AND SODIUM SO REACTIVE? s¬ 4HE¬OUTER¬SHELL¬OF¬HELIUM¬CAN¬TAKE¬NO¬MORE¬ELECTRONS s¬ 4HE¬OUTER¬SHELL¬OF¬SODIUM¬HAS¬¬ELECTRON¬WHICH¬IT¬NEEDS¬TO¬ lose s¬ -ETALS¬NEED¬TO¬LOSE¬ELECTRONS ¬NON METALS¬DO¬NOT

WHAT DO TRANSITION METAL COMPOUND SOLUTIONS LOOK LIKE? s¬ 4RANSITION¬METALS¬ARE¬HARDER¬AND¬STRONGER¬THAN¬'ROUP¬ ¬METALS¬ s¬ 4RANSITION¬METALS¬ARE¬OFTEN¬USED¬AS¬CATALYSTS s¬ 4RANSITION¬METAL¬COMPOUNDS¬OFTEN¬FORM¬COLOURED¬SOLUTIONS

Atomic structure and the periodic table

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Chemistry

Elements and compounds

KEY WORDS

Learning objectives:

balanced compound element equation symbol

sÂŹ IDENTIFYÂŹSYMBOLSÂŹOFÂŹELEMENTSÂŹFROMÂŹTHEÂŹPERIODICÂŹTABLE sÂŹ RECOGNISEÂŹCOMPOUNDSÂŹFROMÂŹTHEIRÂŹFORMULA sÂŹ IDENTIFYÂŹTHEÂŹELEMENTSÂŹINÂŹAÂŹCOMPOUND

All the elements are listed in the periodic table. The elements in the formulae of any compound, no matter how large, can be identified by using the periodic table.

Elements and compounds !NÂŹelementÂŹISÂŹAÂŹSUBSTANCEÂŹTHATÂŹCANNOTÂŹBEÂŹBROKENÂŹ DOWNÂŹCHEMICALLY !ÂŹcompoundÂŹISÂŹAÂŹSUBSTANCEÂŹTHATÂŹCONTAINSÂŹATÂŹLEASTÂŹ TWOÂŹDIFFERENTÂŹELEMENTS ÂŹCHEMICALLYÂŹCOMBINEDÂŹINÂŹ lXEDÂŹPROPORTIONS

1 1

PERIODIC TABLE ELEMENTS 1-20

H

hydrogen

7 3

Li

lithium

23 11

9 4

Be

beryllium

24

Na 12 Mg

sodium magnesium

39 19

K

40 20

11 5

B

boron

27 13

Al

12 6

C

14 7

N

16 8

O

4 2

19 9

F

carbon

nitrogen

oxygen

fluorine

28 14

31 15

32 16

35 17

Si

P

aluminium silicon phosphorus

S

sulfur

He

helium

Cl

chlorine

20 10

Ne

neon

40 18

Ar

argon

Ca

potassium calcium

&IGUREÂŹÂŹTwo sections of the periodic table. Can you ďŹ nd magnesium and oxygen?

+ &IGUREÂŹÂŹMagnesium (metal) reacts with oxygen (gas) to make magnesium oxide (white powder).

+ x z y

&IGUREÂŹÂŹThe reaction of the elements in Figure 1.2 can be represented by models of their atoms. 1

Identify the following substances as elements or compounds. copper

2

14

copper chloride

copper sulfate

Name the elements in beryllium chloride.

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Compounds and elements

1.1

#OPPER¬IS¬AN¬element¬)T¬CANNOT¬BE¬BROKEN¬DOWN¬INTO¬ANY¬ OTHER¬SUBSTANCES ¬BUT¬SALT¬CAN 4HE¬CHEMICAL¬NAME¬FOR¬COMMON¬SALT¬IS¬SODIUM¬CHLORIDE¬ 3ODIUM¬CHLORIDE¬IS¬A¬compound¬3ODIUM¬CHLORIDE¬CAN¬BE¬BROKEN¬ DOWN¬TO¬MAKE¬SODIUM¬AND¬CHLORINE ¬BUT¬THIS¬IS¬NOT¬EASY¬TO¬DO¬ BECAUSE¬THE¬SODIUM¬AND¬CHLORINE¬ARE¬CHEMICALLY¬COMBINED¬ 7E¬NEED¬TO¬USE¬ELECTRICITY¬TO¬MAKE¬SODIUM¬AND¬CHLORINE¬FROM¬ SODIUM¬CHLORIDE 3ODIUM¬AND¬CHLORINE¬CANNOT¬BE¬BROKEN¬DOWN¬ANY¬FURTHER¬ 3ODIUM¬AND¬CHLORINE¬ARE¬ELEMENTS 4HERE¬ARE¬ONLY¬ABOUT¬¬ELEMENTS¬BUT¬THESE¬CAN¬JOIN¬TOGETHER¬ CHEMICALLY¬TO¬MAKE¬AN¬ENORMOUS¬NUMBER¬OF¬COMPOUNDS¬4HEY¬ NEED¬CHEMICAL¬REACTIONS¬TO¬DO¬THIS 3

Identify the elements in potassium bromide.

4

Predict the products when lead iodide is split by electricity.

KEY INFORMATION When chlorine reacts to make a compound it chemically combines and becomes a chloride. Similarly, bromine reacts to become a bromide and oxygen reacts to become an oxide.

Making the element copper into a compound !¬CHEMICAL¬REACTION¬IS¬NEEDED¬TO¬MAKE¬COPPER¬AN¬ELEMENT ¬INTO¬ A¬COMPOUND¬)F¬COPPER¬IS¬BURNED¬IN¬OXYGEN¬IT¬FORMS¬COPPER¬OXIDE¬ #HEMICAL¬REACTIONS¬ALWAYS¬INVOLVE¬THE¬FORMATION¬OF¬ONE¬OR¬MORE¬ NEW¬SUBSTANCES ¬AND¬OFTEN¬INVOLVE¬A¬DETECTABLE¬ENERGY¬CHANGE

DID YOU KNOW? Compounds can only be separated into elements by chemical reactions. To get the element copper back, the oxygen needs to be chemically removed. This is done using hydrogen. The oxygen combines with the hydrogen to make water, another compound. copper oxide + hydrogen → copper + water &IGURE¬¬Copper (an element) burning in oxygen (an element) to make copper oxide (a compound). This is normally done by heating the copper in crucibles. 5

What is the name of the compound made from sodium and oxygen.

6

Oxygen can be removed from iron(III) oxide by carbon monoxide. Identify the element and compound produced.

7

Substance D reacted with hydrogen to form zinc and water. Explain whether substance D is an element or compound. Google search: 'unusual periodic table (images)'

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Chemistry

Atoms, formulae and equations Learning objectives: sÂŹ EXPLAINÂŹTHATÂŹANÂŹELEMENTÂŹCONSISTSÂŹOFÂŹÂŹTHEÂŹSAMEÂŹTYPEÂŹOFÂŹATOMS sÂŹ EXPLAINÂŹTHATÂŹATOMSÂŹJOINÂŹTOGETHERÂŹTOÂŹMAKEÂŹMOLECULES sÂŹ EXPLAINÂŹHOWÂŹFORMULAEÂŹREPRESENTÂŹELEMENTSÂŹANDÂŹCOMPOUNDS

KEY WORDS compound element molecule

All substances are chemicals. Many people say “I don’t want chemicals in my food� not realising that foods are chemicals. Our food is made of compounds and mixtures. Compounds are elements joined together in many different ways. In fact, we are all made of chemical compounds.

Atoms and molecules ElementsÂŹAREÂŹMADEÂŹUPÂŹOFÂŹATOMSÂŹTHATÂŹAREÂŹALLÂŹTHEÂŹSAME #OMPOUNDSÂŹAREÂŹMADEÂŹFROMÂŹATOMSÂŹORÂŹCHARGEDÂŹATOMS ÂŹOFÂŹ DIFFERENTÂŹELEMENTS CH3#//(ÂŹISÂŹAÂŹCOMPOUNDÂŹMADEÂŹFROMÂŹTHREEÂŹELEMENTSÂŹ4HESEÂŹ AREÂŹCARBON ÂŹ# ÂŹHYDROGEN ÂŹ( ÂŹANDÂŹOXYGEN ÂŹ/ÂŹ9OUÂŹWILLÂŹKNOWÂŹITÂŹASÂŹ VINEGARÂŹ)TSÂŹCHEMICALÂŹNAMEÂŹISÂŹETHANOICÂŹACIDÂŹ4HEÂŹATOMSÂŹJOINÂŹBYÂŹ SHARINGÂŹTHEIRÂŹELECTRONSÂŹ4HEÂŹCOMPOUNDÂŹISÂŹMADEÂŹOFÂŹMOLECULES

&IGUREÂŹÂŹVinegar is used in salad dressing. Its chemical name is ethanoic acid. Ethanoic acid is a compound made from carbon, hydrogen and oxygen.

ethanoic acid

&IGUREÂŹÂŹThe molecule in vinegar CH3COOH

&IGUREÂŹÂŹGold is an element. Carbon monoxide is a compound. How could you tell by looking at these diagrams?

)FÂŹTWOÂŹORÂŹMOREÂŹATOMSÂŹJOINÂŹTOGETHERÂŹBYÂŹSHARINGÂŹTHEIRÂŹELECTRONSÂŹ THEÂŹATOMSÂŹFORMÂŹAÂŹmolecule 4WOÂŹEXAMPLESÂŹOFÂŹMOLECULESÂŹAREÂŹOXYGENÂŹANDÂŹWATER 1

For the substances below, write down: a the names of the elements b how many different types of atoms they contain c how many atoms are in the molecule overall. CO2

16

water molecule

&IGUREÂŹÂŹWhich of these is a molecule of an element? How can you tell?

Explain whether the following substances are elements or compounds. C (carbon), CO2 (carbon dioxide), Cl2 (chlorine) and SO3 (sulfur trioxide)

2

oxygen molecule

S8

Cl2

SO3

C60

KEY INFORMATION In a chemical formula, the subscript number on the bottom right is the number of atoms in the molecule, for example C2H6 has two carbon atoms joined to six hydrogen atoms.

C 4H10

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Formulae

1.2

9OU¬CAN¬SEE¬WHICH¬ELEMENTS¬ARE¬IN¬A¬COMPOUND¬BY¬LOOKING¬ AT¬ITS¬formula¬&OR¬EXAMPLE ¬THE¬COMPOUND¬MAGNESIUM¬OXIDE¬ -G/ ¬CONTAINS¬-G¬MAGNESIUM ¬AND¬/¬OXYGEN  ,OOK¬BACK¬AT¬THE¬SECTION¬OF¬THE¬PERIODIC¬TABLE %LEMENTS¬FROM¬'ROUP¬¬AND¬ELEMENTS¬FROM¬'ROUP¬¬COMBINE¬TO¬ MAKE¬COMPOUNDS¬IN¬A¬lXED¬RATIO¬OF¬¬¬ s¬ 4HE¬formula¬OF¬LITHIUM¬mUORIDE¬IS¬,I& %LEMENTS¬FROM¬'ROUP¬¬AND¬ELEMENTS¬FROM¬'ROUP¬¬ALSO¬ COMBINE¬TO¬MAKE¬COMPOUNDS¬IN¬A¬lXED¬RATIO¬OF¬¬¬ DID YOU KNOW?

s¬ 4HE¬FORMULA¬OF¬CALCIUM¬OXIDE¬IS¬#A/ %LEMENTS¬FROM¬'ROUP¬¬AND¬ELEMENTS¬FROM¬'ROUP¬¬COMBINE¬TO¬ MAKE¬COMPOUNDS¬IN¬A¬lXED¬RATIO¬OF¬¬¬¬4HE¬ELEMENT¬THAT¬YOU¬ NEED¬TWO¬OF¬HAS¬A¬SUFlX¬@¬AFTER¬THE¬SYMBOL s¬ 4HE¬FORMULA¬OF¬CALCIUM¬mUORIDE¬IS¬#A&2 %LEMENTS¬FROM¬'ROUP¬¬AND¬ELEMENTS¬FROM¬'ROUP¬¬COMBINE¬TO¬ MAKE¬COMPOUNDS¬IN¬A¬lXED¬RATIO¬OF¬¬¬¬!GAIN ¬THE¬ELEMENT¬ THAT¬YOU¬NEED¬TWO¬OF¬HAS¬A¬SUFlX¬@¬AFTER¬THE¬SYMBOL

Oxygen exists as a pair of atoms not as a single atom. Its formula is O2. In a symbol equation, O2 must be written not just O.

s¬ 4HE¬FORMULA¬OF¬SODIUM¬SULlDE¬IS¬.A23 3

Give the names of the elements in MgSO4 and in CH4.

4

Determine the formulae of lithium chloride, magnesium chloride and potassium oxide.

Equations and balancing 7HEN¬MAGNESIUM¬REACTS¬WITH¬OXYGEN¬IT¬MAKES¬MAGNESIUM¬OXIDE 4HE¬WORD¬equation¬IS ¬ MAGNESIUM¬ ¬

KEY INFORMATION

OXYGEN¬ →¬ MAGNESIUM¬OXIDE

4HE¬symbol¬EQUATION¬IS ¬

-G¬

¬

/¬

→¬

-G/

¬

¬

¬

¬

¬

¬¬¬¬¬

✗

4HIS¬IS¬NOT¬A¬balanced¬EQUATION¬7E¬NEED¬TO¬ADD¬@¬TO¬THE¬FRONT¬ OF¬THE¬FORMULAE¬OF¬MAGNESIUM¬AND¬MAGNESIUM¬OXIDE¬4HIS¬GIVES ¬

-G¬

¬

/¬

→¬

-G/

¬

¬

¬

¬

¬

¬¬¬¬¬

In a balanced equation ‘O2’ means a pair of atoms joined together in a molecule. ‘2Mg’ means two separate atoms, where the ‘2’ is added to balance the equation.

✓

5

Write a balanced equation for the formation of sodium chloride from sodium, Na and chlorine, Cl2.

6

Write a balanced equation for the formation of aluminium oxide Al2O3.

7

Complete and balance the following equation by suggesting values for D, E and F: D N2 + E O2 → F NO2

Google search: 'unusual periodic table (images)'

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Chemistry

Mixtures Learning objectives: sÂŹ RECOGNISEÂŹTHATÂŹALLÂŹSUBSTANCESÂŹAREÂŹCHEMICALS sÂŹ UNDERSTANDÂŹTHATÂŹALLÂŹSUBSTANCESÂŹAREÂŹEITHERÂŹMIXTURES ÂŹ COMPOUNDSÂŹORÂŹELEMENTS sÂŹ EXPLAINÂŹTHATÂŹMIXTURESÂŹCANÂŹBEÂŹSEPARATED

KEY WORDS chromatography ďŹ ltration mixture separation

You will have begun to use of a range of equipment to safely separate chemical mixtures and we need to extend this range of techniques. Filtering and distillation are probably familiar but fractional distillation can also be used to separate mixtures.

Mixtures -ANYÂŹSUBSTANCESÂŹAREÂŹMADEÂŹOFÂŹMIXTURESÂŹMixturesÂŹCANÂŹEASILYÂŹ BEÂŹseparatedÂŹBECAUSEÂŹTHEÂŹCHEMICALSÂŹINÂŹTHEMÂŹAREÂŹNOTÂŹJOINEDÂŹ TOGETHERÂŹ-IXTURESÂŹCANÂŹBEÂŹSEPARATEDÂŹBYÂŹlLTRATION ÂŹCRYSTALLISATION ÂŹ SIMPLEÂŹDISTILLATION ÂŹFRACTIONALÂŹDISTILLATIONÂŹANDÂŹCHROMATOGRAPHY

&IGUREÂŹÂŹSeparating mixtures

,ETSÂŹTAKEÂŹAÂŹMIXTUREÂŹOFÂŹSALTÂŹANDÂŹCOPPERÂŹ4OÂŹSEPARATEÂŹTHEMÂŹWEÂŹ ADDÂŹWATERÂŹTOÂŹTHEÂŹMIXTUREÂŹ4HEÂŹSALTÂŹDISSOLVESÂŹBUTÂŹTHEÂŹCOPPERÂŹ DOESÂŹNOTÂŹ4HEÂŹSALTÂŹSOLUTIONÂŹCANÂŹBEÂŹlLTEREDÂŹTHROUGHÂŹAÂŹlLTERÂŹ PAPER ÂŹLEAVINGÂŹTHEÂŹCOPPERÂŹBEHINDÂŹASÂŹAÂŹRESIDUEÂŹ4HEÂŹSALTÂŹSOLUTIONÂŹ CANÂŹBEÂŹCRYSTALLISEDÂŹTOÂŹMAKEÂŹSOLIDÂŹSALTÂŹCRYSTALSÂŹ4HESEÂŹPHYSICALÂŹ PROCESSESÂŹDOÂŹNOTÂŹINVOLVEÂŹCHEMICALÂŹREACTIONSÂŹANDÂŹNOÂŹNEWÂŹ SUBSTANCESÂŹAREÂŹMADE !FTERÂŹSEPARATING ÂŹSALTÂŹANDÂŹCOPPERÂŹCANÂŹBEÂŹMIXEDÂŹAGAINÂŹ

18

1

Draw a diagram of the equipment used to ďŹ lter salt solution from copper.

2

Explain why a blend of copper and salt is not a compound.

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Separating mixtures

1.3

!ÂŹMIXTUREÂŹCONSISTSÂŹOFÂŹTWOÂŹORÂŹMOREÂŹELEMENTSÂŹORÂŹCOMPOUNDSÂŹ NOTÂŹCHEMICALLYÂŹCOMBINEDÂŹTOGETHERÂŹ4HEÂŹCHEMICALÂŹPROPERTIESÂŹOFÂŹ EACHÂŹSUBSTANCEÂŹINÂŹTHEÂŹMIXTUREÂŹAREÂŹUNCHANGEDÂŹ-IXTURESÂŹCANÂŹBEÂŹ SEPARATEDÂŹBYÂŹPHYSICALÂŹPROCESSESÂŹ4HESEÂŹPROCESSESÂŹDOÂŹNOTÂŹINVOLVEÂŹ CHEMICALÂŹREACTIONS KEY INFORMATION

4HESEÂŹSEPARATIONÂŹPROCESSESÂŹINCLUDE sÂŹ lÂŹLTRATIONÂŹ sÂŹ CRYSTALLISATIONÂŹ ďŹ ltration

sÂŹ DISTILLATION sÂŹ CHROMATOGRAPHY

crystallisation

distillation

chromatography

crystallising dish

Filtration separates insoluble substances from soluble substances and distillation separates liquids that have different boiling points.

crystals

&IGUREÂŹÂŹTechniques for separating mixtures. 3

Which technique would be used to separate coloured inks in a mixture?

4

Which technique would be used to separate alcohol (boiling point 80°C) and water?

Fractional distillation 3OMEÂŹMIXTURESÂŹAREÂŹVERYÂŹCOMPLEXÂŹANDÂŹHAVEÂŹMANYÂŹDIFFERENTÂŹ COMPONENTSÂŹ4HESEÂŹMIXTURESÂŹCANÂŹBEÂŹSEPARATEDÂŹEITHERÂŹA ÂŹBYÂŹ USINGÂŹDIFFERENTÂŹTECHNIQUESÂŹINÂŹSEQUENCEÂŹORÂŹB ÂŹBYÂŹTHEÂŹSAMEÂŹ TECHNIQUEÂŹWHICHÂŹINCLUDESÂŹMULTIPLEÂŹSEPERATIONSÂŹ !NÂŹEXAMPLEÂŹOFÂŹTHEÂŹlÂŹRSTÂŹAPPROACHÂŹISÂŹlÂŹLTRATIONÂŹFOLLOWEDÂŹBYÂŹ CRYSTALLISATION

DID YOU KNOW? Fractional distillation is used to separate the different substances in crude oil.

FRACTIONALÂŹDISTILLATION

!NÂŹEXAMPLEÂŹOFÂŹTHEÂŹSECONDÂŹAPPROACHÂŹISÂŹFRACTIONALÂŹDISTILLATION ÂŹ WHEREÂŹDIFFERENTÂŹLIQUIDSÂŹWITHÂŹDIFFERENTÂŹBOILINGÂŹPOINTSÂŹAREÂŹ SEPARATEDÂŹATÂŹDIFFERENTÂŹPOINTSÂŹINÂŹTHEÂŹPROCESS &RACTIONALÂŹDISTILLATIONÂŹWORKSÂŹBYÂŹUSINGÂŹAÂŹTALLÂŹTOWERÂŹOFÂŹGAPSÂŹANDÂŹ SURFACES ÂŹWHICHÂŹAREÂŹGRADUALLYÂŹCOLDERÂŹTOWARDSÂŹTHEÂŹTOPÂŹ4HEÂŹLIQUIDÂŹ MIXTUREÂŹISÂŹHEATEDÂŹATÂŹTHEÂŹBOTTOMÂŹANDÂŹTHEÂŹLIQUIDSÂŹBOILÂŹTOGETHERÂŹTOÂŹ MAKEÂŹAÂŹMIXTUREÂŹOFÂŹGASESÂŹ!SÂŹEACHÂŹGASÂŹREACHESÂŹAÂŹSURFACEÂŹATÂŹTHEÂŹSAMEÂŹ TEMPERATUREÂŹASÂŹITSÂŹBOILINGÂŹPOINTÂŹORÂŹCONDENSINGÂŹPOINT ÂŹTHATÂŹGASÂŹWILLÂŹ CONDENSEÂŹANDÂŹTHEÂŹCONDENSEDÂŹLIQUIDÂŹWILLÂŹRUNÂŹOFFÂŹ4HEÂŹOTHERÂŹGASESÂŹ CONTINUEÂŹUPÂŹTHROUGHÂŹTHEÂŹGAPSÂŹUNTILÂŹTHEYÂŹREACHÂŹTHEÂŹSURFACEÂŹATÂŹTHEIRÂŹ CONDENSINGÂŹTEMPERATUREÂŹ%VENTUALLYÂŹNEARLYÂŹALLÂŹTHEÂŹGASESÂŹINÂŹTHEÂŹ MIXTUREÂŹWILLÂŹCONDENSEÂŹANDÂŹBEÂŹCOLLECTEDÂŹASÂŹSEPARATEDÂŹLIQUIDSÂŹ4HEÂŹ lÂŹNALÂŹGASÂŹISÂŹLEFTÂŹATÂŹTHEÂŹTOPÂŹOFÂŹTHEÂŹTOWERÂŹANDÂŹISÂŹCOLLECTEDÂŹASÂŹAÂŹGAS 5

Suggest how you would collect a specimen of clean copper sulfate crystals from a mixture of solid copper sulfate, sand and alcohol.

6

Suggest the order of collection from a fractional distillation process of these liquids: a (boiling point 85 °C)

c

(boiling point 35 °C)

b (boiling point 100 °C)

d (boiling point 165 °C)

&IGUREÂŹÂŹFractional distillation of mixtures with different boiling points

Google search: ‘chromatography, filtration, fractional distillation’

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Chemistry KEY WORDS

Changing ideas about atoms Learning objectives: s¬ DESCRIBE¬HOW¬THE¬ATOMIC¬MODEL¬HAS¬CHANGED¬OVER¬TIME s¬ EXPLAIN¬WHY¬THE¬ATOMIC¬MODEL¬HAS¬CHANGED¬OVER¬TIME s¬ UNDERSTAND¬THAT¬A¬THEORY¬IS¬PROVISIONAL¬UNTIL¬THE¬NEXT¬PIECE¬ OF¬EVIDENCE¬IS¬AVAILABLE

electron shell Ernest Rutherford Geiger and Marsden experiment J. J. Thompson James Chadwick John Dalton Niels Bohr

The idea of atoms has changed hugely over the years. At the moment, scientists believe atoms are very small, have a very small mass and are made of protons, electrons and neutrons. Our current theories were developed by imagination, evidence and advances in technology, with each new idea being built on the ideas of earlier scientists.

Developing the atomic theory %XPLANATIONS¬ABOUT¬ATOMS¬BEGAN¬ABOUT¬¬"# ¬WHEN¬THE¬ 'REEK¬PHILOSOPHER¬$EMOCRITUS¬DESCRIBED¬MATERIALS¬AS¬BEING¬ MADE¬OF¬SMALL¬PARTICLES¬(E¬CALLED¬THESE¬PARTICLE¬@ATOMS¬ (OWEVER ¬HE¬HAD¬NO¬EVIDENCE¬)T¬WAS¬JUST¬AN¬IDEA ,ITTLE¬MORE¬WAS¬SUGGESTED¬FOR¬MORE¬THAN¬¬YEARS ¬BUT¬IN¬ ¬THE¬"RITISH¬SCIENTIST¬John Dalton USED¬HIS¬OBSERVATIONS¬TO¬ DESCRIBE¬THE¬ATOM¬IN¬MORE¬DETAIL¬(IS¬MODEL¬DESCRIBED¬AN¬ATOM¬ AS¬A¬@BILLIARD¬BALL

&IGURE¬¬Dalton’s idea of atoms: they were like tiny billiard balls.

$ALTONS¬MODEL¬WAS¬THEN¬CHANGED¬AS¬NEW¬EVIDENCE¬WAS¬FOUND )N¬ ¬¬YEARS¬LATER ¬J. J. Thomson¬DISCOVERED¬THE¬ELECTRON¬ 4HOMSON¬DEVELOPED¬THE¬WAY¬THAT¬THE¬ATOM¬WAS¬THOUGHT¬OF¬ BY¬USING¬A¬@PLUM¬PUDDING¬MODEL¬TO¬DESCRIBE¬ATOMS¬.EGATIVE¬ ELECTRONS¬WERE¬THOUGHT¬TO¬BE¬EMBEDDED¬IN¬A¬BALL¬OF¬POSITIVE¬ CHARGE ¬RATHER¬LIKE¬THE¬FRUIT¬THE¬ELECTRONS ¬ARE¬PART¬OF¬A¬ PUDDING¬THE¬BALL¬OF¬POSITIVE¬CHARGE 

20

1

Suggest why Dalton’s atomic model did not include positive and negative charge.

2

Explain why the discovery of the electron changed the Dalton model of the atom.

KEY INFORMATION At each stage, the explanations of atomic theory were provisional until more convincing evidence was found to make the model better.

AQA GCSE Chemistry: Student Book

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Changing theories

1.4

3OMETIMESÂŹIDEASÂŹCANÂŹDEVELOPÂŹRAPIDLYÂŹBECAUSEÂŹOFÂŹUNEXPECTEDÂŹ RESULTS )NÂŹÂŹGeigerÂŹANDÂŹMarsden HADÂŹREALLYÂŹSURPRISINGÂŹRESULTSÂŹINÂŹTHEIRÂŹ EXPERIMENTÂŹWITHÂŹGOLDÂŹLEAFÂŹANDÂŹALPHAÂŹPARTICLESÂŹ4HESEÂŹRESULTSÂŹLEDÂŹ 'EIGER ÂŹ-ARSDENÂŹANDÂŹRutherford TOÂŹPROPOSEÂŹAÂŹNEWÂŹIDEAÂŹTHATÂŹANÂŹ ATOMÂŹHASÂŹAÂŹNUCLEUSÂŹ)NÂŹ ÂŹ2UTHERFORDÂŹSUGGESTEDÂŹTHEÂŹATOMÂŹHADÂŹ AÂŹPOSITIVELYÂŹCHARGEDÂŹNUCLEUSÂŹANDÂŹMUCHÂŹOFÂŹTHEÂŹATOMÂŹWASÂŹEMPTYÂŹ SPACEÂŹ4HISÂŹWASÂŹTHEÂŹNUCLEARÂŹMODELÂŹOFÂŹTHEÂŹATOM

&IGUREÂŹÂŹRutherford and Geiger in their lab in Manchester, UK.

)NÂŹ ÂŹNiels Bohr USEDÂŹTHEORETICALÂŹCALCULATIONSÂŹTHATÂŹAGREEDÂŹWITHÂŹ EXPERIMENTALÂŹEVIDENCEÂŹTOÂŹADAPTÂŹTHEÂŹNUCLEARÂŹMODELÂŹ(EÂŹEXPLAINEDÂŹ THATÂŹTHEÂŹELECTRONSÂŹORBITEDÂŹTHEÂŹNUCLEUSÂŹINÂŹDElNITEÂŹORBITSÂŹATÂŹSPECIlCÂŹ DISTANCESÂŹFROMÂŹTHEÂŹNUCLEUSÂŹ(EÂŹEXPLAINEDÂŹTHATÂŹAÂŹlXEDÂŹAMOUNTÂŹOFÂŹ ENERGYÂŹAÂŹquantumÂŹOFÂŹENERGY ÂŹISÂŹNEEDEDÂŹFORÂŹANÂŹELECTRONÂŹTOÂŹMOVEÂŹ FROMÂŹONEÂŹORBITÂŹTOÂŹTHEÂŹNEXTÂŹ%LECTRONSÂŹONLYÂŹEXISTÂŹINÂŹTHESEÂŹORBITS

DID YOU KNOW?

Further development of atomic theory

As a challenge you can ďŹ nd out about the Geiger and Marsden experiment that changed the theory from a ‘plum-pudding’ atom to a nuclear atom, it is a famous turning point in the understanding of atoms.

,ATERÂŹEXPERIMENTSÂŹGRADUALLYÂŹLEDÂŹTOÂŹTHEÂŹIDEAÂŹTHATÂŹTHEÂŹPOSITIVEÂŹ CHARGEÂŹOFÂŹANYÂŹNUCLEUSÂŹCANÂŹBEÂŹSUB DIVIDEDÂŹINTOÂŹAÂŹWHOLEÂŹNUMBERÂŹ OFÂŹSMALLERÂŹPARTICLESÂŹ%ACHÂŹOFÂŹTHESEÂŹPARTICLESÂŹHADÂŹTHEÂŹSAMEÂŹ AMOUNTÂŹOFÂŹPOSITIVEÂŹCHARGEÂŹ)NÂŹÂŹTHEÂŹTERMÂŹ@PROTONÂŹWASÂŹlRSTÂŹ USEDÂŹINÂŹPRINTÂŹFORÂŹTHESEÂŹPARTICLES

DID YOU KNOW?

3

Suggest why Bohr proposed that electrons orbited the nucleus in shells.

4

What is meant by the phrase ‘quantum of energy’?

)NÂŹ ÂŹJames Chadwick DISCOVEREDÂŹTHEÂŹNEUTRONÂŹ!GAINÂŹTHISÂŹ DISCOVERYÂŹINVOLVEDÂŹEXPERIMENTALÂŹEVIDENCEÂŹANDÂŹMATHEMATICALÂŹ ANALYSIS 5

Draw a timeline of the discoveries that led to our present understanding of the atomic theory.

6

Suggest why it was twelve years between ďŹ nding protons and neutrons.

The idea of atoms as small particles is not new. However, our ideas about the theory of atoms are still developing. Search on ‘CERN LHC’ to ďŹ nd out more.

Google search: 'timeline of development of atomic theory'

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Chemistry

Modelling the atom Learning objectives: sÂŹ DESCRIBEÂŹTHEÂŹATOMÂŹASÂŹAÂŹPOSITIVELYÂŹCHARGEDÂŹNUCLEUSÂŹ SURROUNDEDÂŹBYÂŹNEGATIVELYÂŹCHARGEDÂŹELECTRONS sÂŹ EXPLAINÂŹTHATÂŹMOSTÂŹOFÂŹTHEÂŹMASSÂŹOFÂŹANÂŹATOMÂŹISÂŹINÂŹTHEÂŹNUCLEUS sÂŹ EXPLAINÂŹTHATÂŹTHEÂŹNUCLEARÂŹRADIUSÂŹISÂŹMUCHÂŹSMALLERÂŹTHANÂŹTHATÂŹ OFÂŹTHEÂŹATOMÂŹANDÂŹWITHÂŹMOSTÂŹOFÂŹTHEÂŹMASSÂŹINÂŹTHEÂŹNUCLEUS

KEY WORDS charge electron nucleus electron shell

Atoms are the building blocks of all matter, both living and non-living, simple and complex. Atoms join together in millions of different ways to make all the materials around us. We can explain how everything, including ourselves, is made by using ideas and models of atoms.

Atoms )NDIVIDUALÂŹATOMSÂŹAREÂŹVERYÂŹSMALLÂŹ4HEREÂŹAREÂŹABOUTÂŹTENÂŹMILLIONÂŹ MILLIONÂŹATOMSÂŹINÂŹTHISÂŹFULLÂŹSTOP !NÂŹATOMÂŹISÂŹMADEÂŹUPÂŹOFÂŹAÂŹnucleusÂŹTHATÂŹISÂŹSURROUNDEDÂŹBYÂŹ ELECTRONS

&IGUREÂŹÂŹMagniďŹ ed image of gold atoms

sÂŹ 4HEÂŹNUCLEUSÂŹCARRIESÂŹTHEÂŹpositive charge sÂŹ Electrons ÂŹWHICHÂŹSURROUNDÂŹTHEÂŹNUCLEUS ÂŹEACHÂŹCARRYÂŹAÂŹ negative charge. )TÂŹDEPENDSÂŹHOWÂŹITÂŹISÂŹMEASUREDÂŹBUTÂŹTHEÂŹDIAMETERÂŹOFÂŹANÂŹATOMÂŹISÂŹ ABOUTÂŹ nÂŹMÂŹ4HATSÂŹÂŹÂŹÂŹMMÂŹ)FÂŹWEÂŹIMAGINEÂŹTHATÂŹANÂŹ ATOMÂŹISÂŹBLOWNÂŹUPÂŹTOÂŹTHEÂŹSIZEÂŹOFÂŹAÂŹFOOTBALLÂŹSTADIUMÂŹTHEÂŹNUCLEUSÂŹ WOULDÂŹBEÂŹTHEÂŹSIZEÂŹOFÂŹAÂŹPEANUTÂŹPLACEDÂŹONÂŹTHEÂŹCENTREÂŹSPOT 1

What is the type of charge in the nucleus?

2

Helium has two positive charges in the nucleus. Predict the number of electrons in a helium atom.

&IGUREÂŹÂŹThe structure of a hydrogen atom. What charge does an electron carry?

More on atoms %LECTRONSÂŹOCCUPYÂŹTHEÂŹSPACEÂŹAROUNDÂŹTHEÂŹNUCLEUSÂŹINÂŹ@SHELLSÂŹ4HEÂŹ SPACEÂŹBETWEENÂŹTHEÂŹNUCLEUSÂŹANDÂŹTHEÂŹelectron shellsÂŹISÂŹEMPTYÂŹ SPACE

22

AQA GCSE Chemistry: Student Book

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4HE¬NUCLEUS¬CONTAINS¬MOST¬OF¬THE¬MASS¬OF¬THE¬ATOM¬AND¬THE¬ ELECTRONS¬CONTRIBUTE¬VERY¬LITTLE¬/N¬THE¬OTHER¬HAND ¬THE¬RADIUS¬ OF¬THE¬ATOM ¬WHERE¬THE¬ELECTRONS¬ARE¬ORBITING ¬IS¬MUCH¬LARGER¬ THAN¬THE¬RADIUS¬OF¬THE¬NUCLEUS¬IN¬THE¬CENTRE

1.5

7HEN¬WE¬ARE¬TALKING¬ABOUT¬THESE¬DIFFERENCES¬WE¬ARE¬TALKING¬ ABOUT¬SMALL¬SIZES¬!TOMS¬ARE very¬SMALL¬!¬TYPICAL¬ATOMIC¬RADIUS¬ IS¬ABOUT¬¬NM¬¬™¬ Â&#x;¬M ¬4HE¬RADIUS¬OF¬A¬NUCLEUS¬IS¬LESS¬THAN¬ ONE¬TEN THOUSANDTH¬OF¬THE¬RADIUS¬OF¬AN¬ATOM¬ABOUT¬¬™¬ Â&#x;¬M  Typical atomic radius 1 × 10

−10

m

Typical radius of a nucleus 1 × 10 −14 m

4HE¬RADIUS¬OF¬AN¬ATOM¬IS¬MEASURED¬IN¬MANY¬DIFFERENT¬WAYS¬4HIS¬IS¬ BECAUSE¬THE¬OUTER¬ELECTRON¬SHELL¬IS¬NOT¬A¬lXED¬BOUNDARY ¬AND¬SO¬ITS¬ POSITION¬CAN¬ONLY¬BE¬MEASURED¬APPROXIMATELY 3

Most of the atom is empty space. What does this suggest about the size of an electron?

4

Explain why the radius of the nucleus is much smaller than the radius of the whole atom.

DID YOU KNOW? An atom of gold has a mass of about 3.3 × 10 −22 g and a radius of about 1.4 × 10 −10 m. Most of the mass of the atom is in the middle, in the nucleus.

!TOMS¬ARE¬VERY¬SMALL¬!¬TYPICAL¬ATOMIC¬RADIUS¬IS¬ABOUT¬¬NM¬ ¬™¬ Â&#x;¬M ¬(OWEVER ¬THE¬RADIUS¬OF¬AN¬ATOM¬INCREASES¬WITHIN¬ A¬GROUP¬OF¬ELEMENTS &OR¬EXAMPLE¬THE¬ATOMIC¬RADII¬OF¬,I ¬.A ¬+ ¬INCREASE¬AS¬MORE¬ ELECTRONS¬ARE¬@ADDED¬TO¬THE¬ATOM¬ 5

Suggest why the radius of potassium is larger than the radius of lithium.

6

The positive charge on a Li nucleus is 3. The positive charge on a Ne nucleus is 10. As more negative electrons are added one by one to atoms from Li up to Ne the radius gets smaller, not bigger. Suggest why. Use ideas about opposite charges.

KEY INFORMATION Remember that the typical radius of a nucleus is less than 1/10 000 th of the typical radius of an atom.

Google search: 'atomic radius Royal Society of Chemistry'

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Chemistry

Relating charges and masses Learning objectives: s¬ DESCRIBE¬THE¬STRUCTURE¬OF¬ATOMS s¬ RECALL¬THE¬RELATIVE¬MASSES¬AND¬CHARGES¬OF¬PROTONS ¬NEUTRONS¬ AND¬ELECTRONS s¬ EXPLAIN¬WHY¬ATOMS¬ARE¬NEUTRAL

We have seen how ideas about atoms have changed over the years. Currently, scientists believe atoms are made of three important particles – protons, electrons and neutrons. s¬ 4HE¬NUMBER¬OF¬protons AND¬neutrons ARE¬IMPORTANT¬IN¬ nuclear reactions s¬ 4HE¬NUMBERS¬OF¬PROTONS¬AND¬electrons¬ARE¬IMPORTANT¬IN¬ chemical reactions

Structure of atoms

KEY WORDS atomic number electron neutral neutron proton symbol

DID YOU KNOW? Even these particles can be broken down further in huge particle accelerators such as the one built deep underneath Switzerland by a joint team of scientists and engineers from many European countries.

!N¬ATOM¬IS¬MADE¬UP¬OF¬A¬NUCLEUS¬THAT¬IS¬SURROUNDED¬BY¬ ELECTRONS s¬ 4HE¬NUCLEUS¬CARRIES¬A¬POSITIVE¬CHARGE s¬ 4HE¬ELECTRONS¬THAT¬SURROUND¬THE¬NUCLEUS¬EACH¬CARRY¬A¬ NEGATIVE¬CHARGE 4HE¬NUCLEUS¬OF¬AN¬ATOM¬IS¬MADE¬UP¬OF¬PROTONS¬AND¬NEUTRONS s¬ 0ROTONS¬HAVE¬A¬POSITIVE¬CHARGE s¬ .EUTRONS¬HAVE¬NO¬CHARGE !N¬ATOM¬ALWAYS¬HAS¬THE¬SAME¬NUMBER¬OF¬PROTONS¬ ¬AS¬ ELECTRONS¬n ¬SO¬ATOMS¬ARE¬ALWAYS¬neutral 4HE¬atomic number¬IS¬THE¬NUMBER¬OF¬PROTONS¬IN¬AN¬ATOM¬4HE¬ ATOMIC¬NUMBER¬FOR¬HELIUM¬IS¬¬BECAUSE¬IT¬HAS¬TWO¬PROTONS 1

Lithium has an atomic number of 3. Predict the number of electrons in lithium.

2

The neon atom has 10 protons. Explain why the neon atom is neutral.

3

Use the periodic table to identify the element with 3 protons.

4

Determine the number of protons in an atom of calcium, Ca.

KEY INFORMATION It is because a helium atom has two protons that it has an atomic number of 2.

Masses and charges 4HE¬NUCLEUS¬OF¬AN¬ATOM¬IS¬MADE¬UP¬OF¬PARTICLES¬PROTONS¬AND¬ NEUTRONS ¬THAT¬ARE¬MUCH¬HEAVIER¬THAN¬ELECTRONS¬4HE¬RELATIVE¬ MASSES¬AND¬CHARGES¬OF¬ELECTRONS ¬PROTONS¬AND¬NEUTRONS¬ARE¬ SHOWN¬IN¬THE¬TABLE

24

&IGURE¬¬The structure of a helium atom. There are the same number of protons and electrons.

AQA GCSE Chemistry: Student Book

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Relative charge

Relative mass

Electron

–1

0.0005

Proton

+1

1

0

1

Neutron

1.6 DID YOU KNOW?

5

A fluorine atom has 9 positive charges, 9 negative charges and a mass of 19. Describe the structure of its atom.

6

A chlorine atom has 17 electrons and a mass of 35. Describe the structure of its atom.

Electrons have such a small relative mass that it is usually treated as zero.

Losing electrons )F¬AN¬ATOM¬HAS¬AN¬ATOMIC¬NUMBER¬OF¬¬AND¬A¬NEUTRAL¬CHARGE ¬ IT¬MUST¬BE¬A¬LITHIUM¬ATOM¬)T¬HAS¬A¬NEUTRAL¬CHARGE¬BECAUSE¬THE¬ ATOM¬HAS¬THREE¬PROTONS¬ ¬AND¬THREE¬ELECTRONS¬n  )F¬THE¬LITHIUM¬ATOM¬LOSES¬ONE¬NEGATIVELY¬CHARGED¬ELECTRON¬IT¬ THEN¬BECOMES¬A¬charged¬PARTICLE¬WITH¬ONE¬POSITIVE¬CHARGE¬THAT¬ IS¬NOT¬BALANCED¬OUT¬BY¬A¬NEGATIVE¬CHARGE Atomic number

Number of protons

Number of electrons

Lithium atom

3

3

3

0

Lithium charged particle

3

3

2

+1

&IGURE¬¬A neutral lithium atom loses an electron and becomes charged.

Charge

)F¬AN¬ATOM¬LOSES¬ELECTRONS¬AND¬BECOMES¬CHARGED ¬THIS¬CHARGED¬ PARTICLE¬IS¬CALLED¬A¬POSITIVE¬ion. 7

If a magnesium atom loses 2 electrons it becomes a charged particle. It still has a mass of 24. Write out the atomic number, number of protons, number of electrons, number of neutrons and the charge of a a magnesium atom b a magnesium ion.

8

Explain why a magnesium atom is neutral but a magnesium ion is charged.

9

Nitride ions have a –3 charge. Work out the number of electrons in a nitride ion, given that the atomic number of nitrogen is 7.

Google search: 'particle adventure'

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Chemistry

Sub-atomic particles

KEY WORDS

Learning objectives: s¬ USE¬THE¬DElNITION¬OF¬ATOMIC¬NUMBER¬AND¬MASS¬NUMBER s¬ CALCULATE¬THE¬NUMBERS¬OF¬PROTONS ¬NEUTRONS¬AND¬ELECTRONS¬ IN¬atoms s¬ CALCULATE¬THE¬NUMBERS¬OF¬SUB ATOMIC¬PARTICLES¬IN¬ISOTOPES¬ AND¬IONS

atomic mass isotope neutrons protons

Smoke detectors, archaeological dating and bone imaging all use isotopes. Some elements have more than one type of atom. These different types of atom have different numbers of neutrons and are called isotopes.

Atomic number and mass number 4HE¬NUCLEUS¬OF¬AN¬ATOM¬IS¬MADE¬UP¬OF¬protons¬AND¬neutrons s¬ 4HE¬ATOMIC¬NUMBER¬IS¬THE¬NUMBER¬OF¬PROTONS¬IN¬AN¬ATOM s¬ 4HE¬mass number¬OF¬AN¬ATOM¬IS¬THE¬TOTAL¬NUMBER¬OF¬PROTONS¬ AND¬NEUTRONS¬IN¬AN¬ATOM )F¬A¬PARTICLE¬HAS¬AN¬ATOMIC¬NUMBER¬OF¬ ¬A¬MASS¬NUMBER¬OF¬¬ AND¬A¬NEUTRAL¬CHARGE ¬IT¬MUST¬HAVE r 11¬PROTONS ¬BECAUSE¬IT¬HAS¬AN¬ATOMIC¬NUMBER¬OF¬11 r 11¬ELECTRONS ¬BECAUSE¬THERE¬ARE¬11¬PROTONS¬AND¬THE¬ATOM¬IS¬ NEUTRAL r 12¬NEUTRONS ¬BECAUSE¬THE¬MASS¬NUMBER¬IS¬23¬AND¬THERE¬ARE¬ ALREADY¬11¬PROTONS¬23¬n¬11¬¬12  (ERE¬ARE¬SOME¬MORE¬EXAMPLES Atomic number

Mass number

Number of protons

Number of electrons

Number of neutrons

Carbon

6

12

6

6

6

Fluorine

9

19

9

9

10

Sodium

11

23

11

11

12

Aluminium

26

1

Complete the row for an atom of aluminium, Al.

2

Work out the number of protons, electrons and neutrons in an atom with an atomic number of 15 and a mass number of 31.

AQA GCSE Chemistry: Student Book

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Isotopes

1.7

All atoms of carbon have 6 protons, so its atomic number is 6. Most carbon atoms have 6 neutrons, so the mass number is 6 + 6 = 12. This form of the carbon atom is written as 126 C. Another form of carbon, 146 C, has an atomic number of 6 (6 protons) and a mass number of 14. It must therefore have 8 neutrons (14 – 6). 146 C is sometimes written as carbon-14. 12 C and 146 C are isotopes of carbon. 6 3

Write the isotope symbol for an atom that has 17 protons and 18 neutrons.

4

Identify all the sub-atomic particles in an atom of carbon-13.

KEY INFORMATION In the symbol 126C, the smaller number (6) is the atomic number and the larger number (12) is the mass number.

Relative abundance of isotopes Most elements have two or more isotopes. For example, hydrogen has three common isotopes. Isotope

Electrons

Protons

Neutrons

Mass number

H

1

1

0

1

H

1

1

1

2

H

1

1

2

3

1 1 2 1 3 1

DID YOU KNOW?

The relative atomic mass of an element is the average mass of the different isotopes of an element. Chlorine’s Ar of 35.5 is an average of the masses of the different isotopes of chlorine. Cl and 37 Cl. If there were 50% There are two main isotopes 35 17 17 of each of the isotopes what would be the average mass? The Cl isotopes. So we need answer is 36. But there are less of the 37 17 a relative abundance calculation:  mass of first isotope  mass of second isotope ×  + ×   % of first isottope   % of second isotope  Ar = 100

The mass numbers of the isotopes of hydrogen are 1, 2 and 3. However, there are not equal proportions of each type of isotope in a sample of hydrogen gas, so the average atomic mass of hydrogen is 1.008.

For example, for chlorine: the abundance values are: 75% 35 Cl and 25% 37 Cl 17 17 Therefore: Ar = (75 × 35) + (25 × 37) 100 2625 + 925 = 100 = 35.5 5

Explain the similarities and differences between the three isotopes of hydrogen.

6

Element X has two isotopes, mass 27 and 29. Calculate the relative atomic mass of X if the first isotope has abundance of 65% and the second isotope has 35% abundance.

Google search: 'web elements'

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Chemistry

Electronic structure

KEY WORDS

Learning objectives: s¬ EXPLAIN¬HOW¬ELECTRONS¬OCCUPY¬@SHELLS¬IN¬AN¬ORDER s¬ DESCRIBE¬THE¬PATTERN¬OF¬THE¬ELECTRONS¬IN¬SHELLS¬FOR¬THE¬lRST¬ ¬ELEMENTS

electronic structure electron shells energy levels

The electrons of an atom are arranged in patterns. The electrons fill up shells in order until that shell can take no more electrons. The next electron goes into the next shell. These patterns are the key to the behaviour of atoms.

The ‘build-up’ of electrons %LECTRONS¬OCCUPY¬SHELLS¬AROUND¬THE¬NUCLEUS¬4HE¬electron¬shell¬ NEAREST¬TO¬THE¬NUCLEUS¬TAKES¬UP¬TO¬TWO¬ELECTRONS¬4HE¬SECOND¬SHELL¬ TAKES¬UP¬TO¬EIGHT¬ELECTRONS¬4HE¬NEXT¬ELECTRONS¬OCCUPY¬A¬THIRD¬SHELL /XYGEN¬HAS¬AN¬ATOMIC¬NUMBER¬OF¬¬)T¬HAS¬EIGHT¬PROTONS¬AND¬SO¬ IT¬HAS¬EIGHT¬ELECTRONS¬IN¬THE¬SPACE¬AROUND¬THE¬NUCLEUS¬4HE¬lRST¬ TWO¬GO¬INTO¬THE¬lRST¬SHELL¬!S¬THE¬lRST¬SHELL¬IS¬NOW¬FULL ¬THE¬NEXT¬ ¬ELECTRONS¬GO¬INTO¬THE¬SECOND¬SHELL¬4HE¬ELECTRON¬PATTERN¬FOR¬ OXYGEN¬IS¬THEN¬  1

Draw the electron pattern for hydrogen and for lithium.

2

Write down the electron pattern for nitrogen.

4HE¬SHELLS¬ARE¬NOT¬lXED¬RINGS¬AND¬ARE¬ALSO¬KNOWN¬AS¬energy levels

&IGURE¬¬For oxygen, the eight electrons can written as 2,6 or be drawn like this.

Electron patterns and groups 4HE¬PERIODIC¬TABLE¬IS¬ARRANGED¬IN¬ORDER¬OF¬@PROTON¬NUMBER 4HERE¬IS¬A¬VERY¬IMPORTANT¬LINK¬BETWEEN¬electronic structure¬AND¬ THE¬PERIODIC¬TABLE¬&OR¬EXAMPLE ¬LET¬US¬CONSIDER¬AN¬ATOM¬OF¬AN¬ ELEMENT¬THAT¬HAS¬THE¬ELECTRONIC¬STRUCTURE¬OF¬   s¬ 4HIS¬ELEMENT¬HAS¬THREE¬ELECTRON¬SHELLS ¬SO¬IT¬IS¬IN¬THE¬THIRD¬ ROW¬OF¬THE¬PERIODIC¬TABLE s¬ )T¬HAS¬SIX¬ELECTRONS¬IN¬ITS¬OUTER¬SHELL ¬SO¬IT¬IS¬IN¬THE¬SIXTH¬COLUMN¬ s¬ 5SING¬THE¬PERIODIC¬TABLE ¬WE¬CAN¬lND¬THAT¬ITS¬ATOMIC¬NUMBER¬ IS¬16¬AND¬IT¬IS¬THE¬ELEMENT¬SULFUR ¬3 H

He

hydrogen

helium

1

2

Li

Be

B

C

N

O

F

Ne

lithium

neon

beryllium

boron

carbon

nitrogen

oxygen

fluorine

3

4

5

6

7

8

9

10

Na

Mg

Al

Si

P

S

Cl

Ar

sodium

magnesium

aluminium

silicon

phosphorus

sulfur

chlorine

argon

11

12

13

14

15

16

17

18

K

Ca

potassium

calcium

19

20

this row has the elements of period 3

&IGURE¬¬Period 3 contains the elements from sodium to argon.

28

AQA GCSE Chemistry: Student Book

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7EÂŹCANÂŹALSOÂŹWORKÂŹTHEÂŹOTHERÂŹWAYÂŹ&INDÂŹTHEÂŹELEMENTÂŹWITHÂŹTHEÂŹ ATOMICÂŹNUMBERÂŹÂŹINÂŹTHEÂŹPERIODICÂŹTABLEÂŹ4HISÂŹISÂŹMAGNESIUM ÂŹ-G

1.8

sÂŹ )TÂŹISÂŹINÂŹTHEÂŹTHIRDÂŹROW ÂŹSOÂŹITÂŹHASÂŹTHREEÂŹELECTRONÂŹSHELLS sÂŹ )TÂŹISÂŹINÂŹTHEÂŹSECONDÂŹCOLUMN ÂŹSOÂŹITÂŹHASÂŹTWOÂŹELECTRONSÂŹINÂŹITSÂŹ OUTERÂŹSHELL sÂŹ )TÂŹHASÂŹTHEÂŹELECTRONICÂŹSTRUCTUREÂŹOFÂŹ2 8 2 4HEÂŹCOLUMNÂŹOFÂŹELEMENTSÂŹISÂŹKNOWNÂŹASÂŹAÂŹGroupÂŹ3OÂŹCOLUMNÂŹÂŹISÂŹ 'ROUPÂŹ 3

An atom of an element has an atomic number of 11.

&IGUREAn atom of uorine, 2,7.

a Draw a diagram to show the pattern of electrons. b Identify the element. c Identify the group to which it belongs. 4

Work out the electronic structure of the element that has an atomic number 9.

5

An element has a mass number of 40 and an electron arrangement of 2,8,8,2. Identify the element and work out the number of neutrons.

Maximum numbers 4HEÂŹELECTRONICÂŹSTRUCTUREÂŹOFÂŹEACHÂŹOFÂŹTHEÂŹlRSTÂŹÂŹELEMENTSÂŹCANÂŹBEÂŹ WORKEDÂŹOUTÂŹUSING sÂŹ THEÂŹATOMICÂŹNUMBERÂŹOFÂŹTHEÂŹELEMENT sÂŹ THEÂŹMAXIMUMÂŹNUMBERÂŹOFÂŹELECTRONSÂŹINÂŹEACHÂŹSHELL 4HEÂŹTHIRDÂŹSHELLÂŹTAKESÂŹUPÂŹTOÂŹEIGHTÂŹELECTRONSÂŹBEFOREÂŹTHEÂŹFOURTHÂŹ SHELLÂŹSTARTSÂŹTOÂŹlLLÂŹ%LEMENTÂŹ ÂŹPOTASSIUM ÂŹHASÂŹTHEÂŹELECTRONICÂŹ STRUCTUREÂŹ   

DID YOU KNOW? It took many years for scientists to work out the theory of electrons occupying shells. They started with the behaviour of elements and then looked for patterns.

5SEÂŹTHEÂŹPERIODICÂŹTABLEÂŹTOÂŹHELPÂŹYOUÂŹTOÂŹANSWERÂŹTHESEÂŹQUESTIONS 6

Work out the electronic structure of argon.

7

Use a blank periodic table sheet to draw out the electronic structure of the ďŹ rst 20 elements, putting the diagram in the correct box. What do you notice about the group number and the number of electrons in the outer shell?

8

KEY INFORMATION

The electronic conďŹ guration for the ion of an unknown isotope 26 3+ X is 2,8. a Work out the atomic number of element X. b Determine the number of neutrons in X.

&IGUREÂŹÂŹAn atom of phosphorus, 2,8,5.

Do not try to use this method to work out the electronic structure of gold, as it has 79 electrons.

c Explain which group in the periodic table element X is in.

Google search: 'electronic structure'

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Chemistry

The periodic table

KEY WORDS

Learning objectives:

electron shells energy levels group period

s¬ EXPLAIN¬HOW¬THE¬ELECTRONIC¬STRUCTURE¬OF¬ATOMS¬FOLLOWS¬A¬PATTERN s¬ RECOGNISE¬THAT¬THE¬NUMBER¬OF¬ELECTRONS¬IN¬AN¬ELEMENTS¬ OUTER¬SHELL¬CORRESPONDS¬TO¬THE¬ELEMENTS¬GROUP¬NUMBER s¬ EXPLAIN¬THAT¬THE¬ELECTRONIC¬STRUCTURE¬OF¬TRANSITION¬METALS¬ POSITION¬THE¬ELEMENTS¬INTO¬THE¬TRANSITION¬METAL¬BLOCK

We know that the periodic table is arranged in rows and columns and the elements are written in order of their atomic number. So why are all the elements in the last column all unreactive gases? Why are all the elements in the first column highly reactive metals? The answer lies in the pattern of their electrons.

The order of elements and electron patterns

KEY INFORMATION

!S¬WE¬HAVE¬SEEN ¬THE¬ELEMENTS¬IN¬THE¬PERIODIC¬TABLE¬ARE¬ ARRANGED¬IN¬ORDER¬OF¬ATOMIC¬NUMBER¬!TOMIC¬NUMBER¬IS¬THE¬ NUMBER¬OF¬PROTONS¬IN¬AN¬ATOM¬!S¬ATOMS¬ARE¬NEUTRAL ¬THE¬ ATOMIC¬NUMBER¬ALSO¬GIVES¬THE¬NUMBER¬OF¬ELECTRONS¬IN¬AN¬ATOM

Remember:

&OR¬EXAMPLE ¬THE¬ATOMIC¬NUMBER¬OF¬HYDROGEN¬IS¬ ¬CARBON¬IS¬¬ AND¬SODIUM¬IS¬¬4HIS¬MEANS¬THAT¬HYDROGEN¬IS¬THE¬lRST¬ELEMENT¬ IN¬THE¬TABLE ¬CARBON¬IS¬THE¬SIXTH¬AND¬SODIUM¬IS¬THE¬ELEVENTH

s¬ ¬THE¬lRST¬SHELL¬OF¬ELECTRONS¬ carries up to 2 electrons s¬ ¬THE¬SECOND¬SHELL¬CARRIES¬ up to 8 electrons.

7E¬HAVE¬ALSO¬SEEN¬THAT¬ELECTRONS¬OCCUPY¬ENERGY¬LEVELS¬OR¬ SHELLS ¬%ACH¬ELEMENT¬HAS¬A¬PATTERN¬OF¬ELECTRONS¬KNOWN¬AS¬ITS¬ ELECTRONIC¬STRUCTURE ¬THAT¬IS¬BUILT¬UP¬IN¬A¬PARTICULAR¬ORDER 4HE¬ELECTRONIC¬STRUCTURE¬OF¬EACH¬OF¬THE¬lRST¬¬ELEMENTS¬CAN¬BE¬ WORKED¬OUT¬USING s¬ THE¬ATOMIC¬NUMBER¬OF¬THE¬ELEMENT s¬ THE¬MAXIMUM¬NUMBER¬OF¬ELECTRONS¬ALLOWED¬IN¬EACH¬SHELL

&IGURE¬¬The electron pattern of a lithium atom.

4HE¬THIRD¬SHELL¬TAKES¬UP¬TO¬EIGHT¬ELECTRONS¬BEFORE¬THE¬FOURTH¬ SHELL¬STARTS¬TO¬lLL¬%LEMENT¬ ¬THEREFORE ¬HAS¬THE¬ELECTRONIC¬ STRUCTURE¬    1

Which element has the atomic number 13?

2

Which element has an electronic structure of 2,8,7?

Arrangement of groups and periods 4HE¬lRST¬ROW¬OF¬THE¬PERIODIC¬TABLE¬CONTAINS¬THE¬ELEMENTS¬ HYDROGEN¬AND¬HELIUM¬4HESE¬TWO¬ELEMENTS¬ONLY¬HAVE¬ELECTRONS¬ IN¬THE¬lRST¬SHELL¬ENERGY¬LEVEL  ,ITHIUMS¬THIRD¬ELECTRON¬GOES¬INTO¬THE¬NEXT¬ELECTRON¬SHELL¬ ,ITHIUM¬STARTS¬A¬NEW¬ROW¬IN¬THE¬PERIODIC¬TABLE¬4HIS¬SECOND¬ROW¬ IS¬CALLED¬THE¬SECOND¬period

30

the atomic number of hydrogen is 1

Li Be 3

4

H

He

1

2

B C N O F Ne 5

6

7

8

9

10

Na Mg Al Si P S Cl Ar 11

12

13

14

15

16

17

18

K Ca 19

20

&IGURE¬¬Lithium has an atomic number of 3. It has three protons and three electrons.

AQA GCSE Chemistry: Student Book

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,ETSÂŹCONSIDERÂŹANÂŹATOMÂŹOFÂŹTHEÂŹELEMENTÂŹTHATÂŹHASÂŹTHEÂŹELECTRONICÂŹ STRUCTUREÂŹOFÂŹ  ÂŹ7EÂŹCANÂŹWORKÂŹOUTÂŹTHATÂŹITÂŹISÂŹINÂŹTHEÂŹTHIRDÂŹROWÂŹ OFÂŹTHEÂŹPERIODICÂŹTABLEÂŹ4HISÂŹATOMÂŹHASÂŹTHREEÂŹELECTRONÂŹSHELLSÂŹ)TÂŹHASÂŹ TWOÂŹELECTRONSÂŹINÂŹITSÂŹOUTERÂŹSHELLÂŹ)TSÂŹATOMICÂŹNUMBERÂŹISÂŹÂŹ9OUÂŹCANÂŹ WORKÂŹTHISÂŹOUTÂŹBYÂŹADDINGÂŹUPÂŹTHEÂŹNUMBERÂŹOFÂŹELECTRONS ÂŹ,OOKINGÂŹ ATÂŹTHEÂŹPERIODICÂŹTABLEÂŹTHEÂŹATOMÂŹISÂŹOFÂŹTHEÂŹELEMENTÂŹMAGNESIUM ÂŹ 3OÂŹTHEÂŹELEMENTÂŹISÂŹTHEREFORE ÂŹINÂŹTHEÂŹTHIRDÂŹperiod ,OOKINGÂŹAGAIN ÂŹTHISÂŹATOMÂŹONLYÂŹHASÂŹTWOÂŹELECTRONSÂŹINÂŹITSÂŹOUTERÂŹ SHELL ÂŹSOÂŹITÂŹISÂŹINÂŹTHEÂŹSECONDÂŹCOLUMNÂŹ!ÂŹCOLUMNÂŹISÂŹKNOWNÂŹASÂŹAÂŹ groupÂŹ4HISÂŹSECONDÂŹCOLUMNÂŹISÂŹKNOWNÂŹASÂŹ'ROUPÂŹ !ÂŹCOLUMNÂŹISÂŹKNOWNÂŹASÂŹAÂŹGROUPÂŹ4HEÂŹGROUPÂŹNUMBERÂŹREFERSÂŹTOÂŹTHEÂŹ NUMBERÂŹOFÂŹELECTRONSÂŹINÂŹTHEÂŹOUTSIDEÂŹSHELL 7EÂŹHAVEÂŹSEENÂŹTHATÂŹTHEÂŹELECTRONÂŹPATTERNÂŹFORÂŹ,IÂŹISÂŹ ÂŹ7EÂŹCANÂŹ WORKÂŹOUTÂŹTHATÂŹTHEÂŹPATTERNÂŹFORÂŹ.AÂŹÂŹELECTRONS ÂŹISÂŹ  ÂŹANDÂŹ+ÂŹÂŹ ELECTRONS ÂŹISÂŹ   ÂŹ!LLÂŹOFÂŹTHESEÂŹELEMENTSÂŹHAVEÂŹONEÂŹELECTRONÂŹINÂŹ THEIRÂŹOUTSIDEÂŹSHELLÂŹ4HEYÂŹAREÂŹALLÂŹINÂŹTHEÂŹlRSTÂŹCOLUMNÂŹ4HISÂŹCOLUMNÂŹ ISÂŹKNOWNÂŹASÂŹ'ROUPÂŹ 3 4

1.9 KEY INFORMATION The Periodic Table is arranged in rows (called periods). Each period number is the same as the number of electron shells. Each period contains the elements whose outside shell of electrons is â€˜ďŹ lling up’.

What is the pattern of electrons in the atom of the element with an atomic number 16? Identify the element, its group and its period.

this column has the elements of group 1

H hydrogen 1

To which group and period does the element chlorine belong?

Electronic structure and behaviour of elements %LEMENTÂŹÂŹHASÂŹTHEÂŹELECTRONICÂŹSTRUCTUREÂŹ    ÂŹANDÂŹISÂŹINÂŹ'ROUPÂŹ 4HEÂŹFOURTHÂŹSHELLÂŹCANÂŹTAKEÂŹUPÂŹTOÂŹÂŹELECTRONS ÂŹBUTÂŹTHEÂŹNEXTÂŹ ELEMENTÂŹELEMENTÂŹNUMBERÂŹ ÂŹISÂŹNOTÂŹINÂŹ'ROUPÂŹÂŹ)NSTEADÂŹTHEÂŹ NEXTÂŹÂŹELEMENTSÂŹNUMBERSÂŹÂŹTOÂŹ ÂŹINÂŹPERIODÂŹÂŹAREÂŹPARTÂŹOFÂŹTHEÂŹ lRSTÂŹtransition element periodÂŹ4RANSITIONÂŹELEMENTSÂŹHAVEÂŹ CHARACTERISTICSÂŹTHATÂŹAREÂŹSIMILARÂŹTOÂŹEACHÂŹOTHERÂŹ&ORÂŹEXAMPLE ÂŹIRONÂŹ BEHAVESÂŹMOREÂŹLIKEÂŹCOPPERÂŹTHANÂŹSODIUM

Li

Be

B

C

lithium 3

beryllium 4

boron 5

carbon 6

Na

Mg

Al

Si

sodium 11

magnesium 12

aluminium 13

silicon 14

K

Ca

potassium 19

calcium 20

&IGUREÂŹÂŹThese elements are in the ďŹ rst column as they all have one electron in their outside shell.

%LEMENTSÂŹINÂŹGROUPSÂŹOFTENÂŹBEHAVEÂŹSIMILARLYÂŹTOÂŹOTHERÂŹELEMENTSÂŹÂŹ INÂŹTHATÂŹGROUP sÂŹ THEÂŹELEMENTSÂŹINÂŹ'ROUPÂŹÂŹAREÂŹALLÂŹHIGHLYÂŹREACTIVEÂŹMETALS sÂŹ THEÂŹELEMENTSÂŹINÂŹ'ROUPÂŹÂŹTHEÂŹHALOGENS ÂŹALLÂŹREACTÂŹWITHÂŹÂŹ 'ROUPÂŹÂŹMETALSÂŹTOÂŹMAKEÂŹSALTS sÂŹ THEÂŹELEMENTSÂŹINÂŹ'ROUPÂŹÂŹAREÂŹALLÂŹUNREACTIVEÂŹORÂŹNOBLE ÂŹGASES 4HISÂŹPATTERNÂŹISÂŹBECAUSEÂŹTHEÂŹelements in each group have the same number of electrons in their outer shells. 5SEÂŹTHEÂŹPERIODICÂŹTABLEÂŹTOÂŹHELPÂŹYOUÂŹTOÂŹANSWERÂŹTHESEÂŹQUESTIONS 5

What are the electronic structures of F and Cl? Why are they both found in Group 7?

6

Identify the elements in Group 6.

Google search: 'adaptations of leaves for photosynthesis'

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AQA GCSE (9 1) Chemistry Student Book  
AQA GCSE (9 1) Chemistry Student Book