Pure Chem S4 Notes (BT 2020) - Final Update 2 Jun 2022

Pure Chemistry Notes 1 PURE CHEMISTRY NOTES 2020 © SEC 4

Pure Chemistry Notes 2

Pure Chemistry Notes 3 4EXP CHEMISTRY TOPICS No. Topics Page Remarks 1 Periodic Table 4 2 Rate of Reaction 18 3 Redox Reaction - Oxidation & Reduction 36 4 Energy - Exothermic & Endothermic Reactions 44 5 Electrolysis 57 6 Air 78 7 Harber Process 90 8 Organic Chemistry - Petroleum & Alternative Sources of Fuel 94 9 Organic Chemistry - Alkanes 99 10 Organic Chemistry - Alkenes 103 11 Organic Chemistry - Alcohols 109 12 Organic Chemistry - Carboxylic Acids 114 13 Organic Chemistry - Esters 117 14 Organic Chemistry - Addition Polymers 126 15 Organic Chemistry - Condensation Polymers 131

Pure Chemistry Notes 4 Periodic Table The Periodic Table is an arrangement and classification of the elements. It can be used to predict the properties of elements from trends that are observed. GROUP (Vertical Column) • Vertical columns of elements in the Periodic Table • The Group number indicates the number of valence electrons in an atom of an element. • Element in the same group have the same number of valence electrons, hence they form ions of the same charges and have similar chemical properties (reaction) Element Electronic Configuration Valence electrons Group Ions Lithium 2.1 1 I Li+ Sodium 2.8.1 1 I Na+ Potassium 2.8.8.1 1 I K+ Oxygen 2.6 6 VI O2- Sulphur 2.8.6 6 VI S2- Beryllium 2 2 II Be2+ Magnesium 2.8.2 2 II Mg2+

Pure Chemistry Notes 5 Exception Element Electronic Configuration Valence electrons Group Helium 2 2 0 Helium is not located in Group II, as its 1st shell is completely full and it has a stable noble gas configuration. Trends down a Group The following trends are observed when down a Group: • The proton number becomes bigger. The number of energy levels increases as you move down a group as the number of electrons increases. Each subsequent energy level is further from the nucleus than the last. Therefore, the atomic radius increases as the group and energy levels increase. • The properties of the elements become more metallic. This is because on going down the group, the elements lose electrons more easily, as the valence electrons become spaced further away from the positive nucleus. PERIOD (Horizontal row) • Horizontal rows of elements in the Periodic Table. • The Periodic Table is a list of elements arranged in order of their increasing atomic or proton number • The Period number indicates the number of occupied electron shells in an atom of an element.

Pure Chemistry Notes 6 Trends across a Period ▪ Across the period, elements changes from Metals to Non-metals ▪ A decrease in metallic properties ▪ An increase in non-metallic properties ▪ This results in the different types of oxides formed. Group I II III IV V VI VII 0 Symbol Na Mg Al Si P S Cl Ar Properties Metallic Metalloid (Elements having t