Pure Chem S3 Notes (BT 2019) Final Update 23 July 2021

Pure Chemistry Notes 1 PURE CHEMISTRY NOTES 2021 ©

Pure Chemistry Notes 2

Pure Chemistry Notes 3 3EXP CHEMISTRY TOPICS No. Topics Page Remarks 1 Atomic Structure 4 2 Chemical Formula 8 3 Balancing equations 11 4 State Symbols 12 5 Element, Mixtures and Compounds 14 6 Experimental Techniques & Measurement 17 7 Separation Techniques 24 8 Kinetic Particle Theory 33 9 Chemical Bonding – Ionic 39 10 Chemical Bonding - Covalent 42 11 Acids and Their Reactions 47 12 Alkalis and Their Reactions 53 13 Types of Oxides 63 14 Salt Solubility 66 15 Salt Preparation 67 16 Metals – Properties of Metals 78 17 Metals – Reactivity of Metals 82 18 Metals - Extraction 93 19 Metals – Rusting and Prevention 98 20 Mole Concept 103 23 Definition List 132 24 Colours of Common Substances 142

Pure Chemistry Notes 4 ATOMIC STRUCTURE Atoms are the smallest particles an element can exists. They are electrically NEUTRAL (which means they have equal number of protons and electrons) They consist of: (a) Nucleus where protons (+) and neutrons (no charge) are found and; (b) Electron shells where electrons (-) are found. When the number of electrons and protons are not equal, the atom is no longer electrically neutral. It has become a: (a) Positively charged ION (More protons than electrons) → Cation, X+ (b) Negatively charged ION (Less protons than electrons) → Anion, Y- IONS – Charged Atoms To obtain a stable noble gas structure, atoms have to: (a) Give away electrons → form Positive (+) ions (b) Take in electrons → form Negative (-) ions Al atom (2.8.3) Al3+ ion (2.8) 3+ Al Al 2- O O O atom (2.6) O2- ion (2.8) 3 negative electrons are lost 2 negative electrons are taken in 3 negative electrons are lost. The number of protons do not change. There are 13 Protons and 10 electrons. Hence overall is +3 2 negative electrons are taken in. There are now 10 electron and 8 protons. Hence the overall is -2

Pure Chemistry Notes 5 Particles Location Charge Mass Remarks Proton Nucleus +1 1 unit Protons and neutrons in the nucleus of an atom are collectively known as NUCLEONS Neutron Nucleus No charge 1 unit Electron Electron shell -1 1/1840 ISOTOPES Definition: Isotopes are atoms of the same element with the same number of protons and electrons but different number of neutrons. Hence isotopes have the same: (a) Number of protons and electrons (b) Chemical properties due to similar electronic configuration But they have different: (a) Number of neutrons (b) Physical properties like mass, density Common Isotopes are: 25% of isotopes of Chlorine are 37-Cl and 75% of isotopes of Chlorine are 35-Cl Hence the average mass of Chlorine is calculated as shown: Relative atomic mass of Chlorine = 25% x 37 + 75% x 35 = 35.5 Hence Chlorine in the Periodic Table is Other Isotopes are: 𝐶𝑙37 17 𝐶𝑙35 17 𝐶𝑙35.5 17 𝐻1 1 𝐻2 1 𝐻3 1 protium deuterium tritium

Pure Chemistry Notes 6 IONS FORMULA LIST Atom Ion Ion Formula Remarks Chlorine Chloride Cl- Negative ions formed ends with ~ide Positive ions formed do not change their name Fluorine Flouride F- Bromine Bromide Br- Iodine Iodide I- Oxygen Oxide O2- Sulfur Sulfide S2- Nitrogen Nitride N3- Hydrogen Hydride H- Phosphorus Phosphide P3- COMPLEX IONS FORMULA Complex Ion Formula Hydroxide OH- Sulfate SO42- Carbonate CO32- Nitrate NO3- Ammonium NH4+ COMPLEX IONS FORMULA (ADDITIONAL LIST) Complex Ion Formula Sulfite SO32- Hydrogen carbonate HCO3- Hydrogen sulfate HSO4- Hydrogen sulphite HSO3- Phosphate PO43- Thiosulfate S2O32- Sodium hydroxide - NaOH (1:1) Copper (II) hydroxide - Cu(OH)2 (1:2) Aluminium nitrate - Al(NO3)3 (1:3) Iron (III) carbonate – Fe2(CO3)3 (2:3) Copper (II) sulfate – CuSO4 (1:1) Ammonium sulfate – (NH4)2SO4 (2:1) Sodium phosphide - Na3PO4 (3:1) Lithium hydrocarbonate – NaHCO3 (1:1) Sodium hydrocarbonate – NaHCO3 (1:1) Ammonium sulfate – (NH4)2SO4 (2:1)

Pure Chemistry Notes 7 POSITIVE IONS FORMULA (ADDITIONAL LIST) Ion Formula Silver Ag+ Zinc Zn2+ Copper (I) Cu+ Copper (II) Cu2+ Iron (II) Fe2+ Iron (III) Fe3+ Lead (II) Pb2+ Lead (IV) Pb4+ IMPORTANT FORMULA Acid Formula Hydrochloric acid HCl (aq) Nitric acid HNO3 Sulfuric acid H2SO4 Sulfurous acid H2SO3 Phosphoric acid H3PO4 Carbonic acid H2CO3 Gas Formula Hydrogen chloride gas HCl (g) Ammonia NH3 Methane CH4 Other chemical Formula Hydrogen peroxide H2O2 Limestone CaCO3 Limewater Ca(OH)2 Quicklime CaO For transitiion metals with 2 oxidation state eg Copper which can be Cu+ and Cu2+ The charge of the metal must be specified. CuSO4 – Copper (II) sulfate Fe(OH)3 – Iron (III) hydroxide

Pure Chemistry Notes 8 CHEMICAL FORMULA Simple Ions – There is no bracket used. Name of compound Positive ion Negative ion Formula Ratio Cation : Anion in compound Sodium oxide Na+ O2- Na2O 2 : 1 Lithium oxide Li+ O2- Li2O 2 : 1 Calcium oxide Ca2+ O2- CaO 1 : 1 Aluminium oxide Al3+ O2- Al2O3 2 : 3 Sodium nitride Na+ N3- Na3N 3 : 1 Aluminium nitrIde Al3+ N3- AlN 1 : 1 Transition metals with variable oxidation states – The roman numeral in the bracket will give the cation its charge. Name of compound Positive ion Negative ion Formula Ratio Cation : Anion in compound Copper (I) oxide Cu+ O2- Cu2O 2 : 1 Copper (II) oxide Cu2+ O2- CuO 1 : 1 Iron (II) chloride Fe2+ Cl- FeCl2 1 : 2 Iron (III) chloride Fe3+ Cl- FeCl3 1 : 3 Lead (II) bromide Pb2+ Br- PbBr2 1 : 2 Lead (IV) bromide Pb4+ Br- PbBr4 1 : 4

Pure Chemistry Notes 9 Complex Ions For Complex ions, a bracket is used when there is more than one set. Name of compound Positive ion Negative ion Formula Ratio Cation : Anion in compound Sodium hydroxide Na+ OH- NaOH 1 : 1 Zinc hydroxide Zn2+ OH- Zn(OH)2 1 : 2 Aluminium hydroxide Al3+ OH- Al(OH)3 1 : 3 Name of compound Positive ion Negative ion Formula Ratio Cation : Anion in compound Sodium sulfate Na+ SO42- Na2SO4 2 : 1 Zinc sulfate Zn2+ SO42- ZnSO4 1 : 1 Aluminium sulfate Al3+ SO42- Al2(SO4)3 2 : 3 Name of compound Positive ion Negative ion Formula Ratio Cation : Anion in compound Sodium carbonate Na+ CO32- Na2CO3 2 : 1 Zinc carbonate Zn2+ CO32- ZnCO3 1 : 1 Aluminium carbonate Al3+ CO32- Al2(CO3)3 2 : 3 Name of compound Positive ion Negative ion Formula Ratio Cation : Anion in compound Sodium nitrate Na+ NO3- NaNO3 1 : 1 Zinc nitrate Zn2+ NO3- Zn(NO3)2 1 : 2 Aluminium nitrate Al3+ NO3- Al(NO3)3 1 : 3 Name of compound Positive ion Negative ion Formula Ratio Cation : Anion in compound Ammonium nitrate NH4+ NO3- NH4NO3 1 : 1 Ammonium carbonate NH4+ CO32- (NH4)2CO3 2 : 1 Ammonium sulfate NH4+ SO42- (NH4)2SO4 2 : 1 Ammonium hydroxide NH4+ OH- NH4OH 1 : 1

Pure Chemistry Notes 10 NAMING OF COMPOUNDS WITH TRANSITION METALS The metals listed below can have more than one oxidation state (charge). Hence it is important to state which oxidation state is present in the compound during naming Metal / Oxidation State Formula of ion Copper (I) Cu+ Copper (II) Cu2+ Iron (II) Fe2+ Iron (III) Fe3+ Lead (II) Pb2+ Lead (IV) Pb4+ Formula Name of compound Cu2S Copper (I) sulfide CuCl2 Copper (II) chloride FeCl2 Iron (II) chloride Fe2O3 Iron (III) oxide PbI2 Lead (II) iodide PbO2 Lead (IV) oxide NAMING OF COVALENT COMPOUNDS (NON METALLIC COMPOUNDS) The following prefixes are used: 1 ~ Mono 2 ~ Di 3 ~ Tri Formula Name of compound CO Carbon monoxide CO2 Carbon dioxide SO3 Sulfur trioxide SO2 Sulfur dioxide F2O Oxygen difluoride