Chemistry AS Level Definitions Physical Chemistry Term/Law 1 Links Frequency Definition (2014 – 2021) 01 ATOMIC STRUCTURE Number of protons in the nucleus of each atom in an Atomic number element 0 2 Nucleon number Total number of protons and neutrons 1 3 Isotope Same number of proton, different number of neutrons 3 4 Ground state Lowest allowed energy state of an atom, molecule or ion 0 5 First ionisation energy 6 Empirical formula 7 R E 8 L A 9 T I 10 V E Periodic Energy required to remove one mole of electrons from table each atom in one mole of gaseous atoms of an element 02 ATOMS, MOLECULES & STOICHIOMETRY Simplest whole number ratio of elements in a compound. Average masses of one atom atomic isotopic molecular ! Average masses of one atom of the relative to A isotope mass of a carbon- S Sum of the atomic masses of all S atoms in the molecular form !" of the Sum of the atomic masses of all atoms in the formula form Molar mass Mass of one mole of a substance 12 Mole The amount of substance containing as many particles as there are atoms in 12 g of carbon-12 03 CHEMICAL BONDING Electrostatic attraction between positive metal ions and Metallic bonding delocalised electrons 14 Ionic bonding Transfer of electrons from a metallic element to a nonmetallic element 15 Covalent bonding Organic Chemistry 16 Dative/coordinate bond 17 Electronegativity NH4+ CO Periodic Table Group 17 3 12 atom. 11 13 0 3 M formula 3 Electrostatic attraction between the nuclei of two atoms and a shared pair of electrons A covalent bond where both electrons come from The same atom Ability of an atom to attract a pair of electrons in a 2 2 0 1 1 0 0 1 covalent bond 1 Whereby electron distribution is not equal 1 18 Bond polarity 19 sp hybridisation Alkynes Overlapping of s and one p orbitals 1 20 sp2 hybridisation Alkenes Overlapping of s and two 2 orbitals 1 21 sp3 hybridisation Alkanes Overlapping of s and three p orbitals 1 Group 17 1 Prepared by Chermaine Lim (2022) Chemistry AS Level Definitions 22 23 04 STATES OF MATTER Easily vaporised Volatile Activation energy 05 CHEMICAL ENERGETICS Minimum amount of energy needed before a reaction can reaction kinetics 24 25 Bond enthalpy 1 Group 17 Hess Law 0 occur Amount of energy required to break one mole of a bond 1 in a gaseous molecule Total energy change for a chemical reaction is independent of the route by which the energy change 1 occurs. 26 reaction 𝚯 27 28 Standard ∆𝑯𝒓 formation 𝚯 enthalpy ∆𝑯𝒇 change combustion of ∆𝑯𝒄 𝚯 neutralisation 29 ∆𝑯𝒏𝒆𝒖𝒕 𝚯 30 Oxidising agent 31 Reducing agent 32 Disproportionation Alkanes Equilibria Group 17 Heat change when the reactants in a stoichiometric equation react to give products one mole of a compound is formed from its elements one mole of fuel is burnt in excess oxygen one mole of water is formed by reacting an acid and alkali 06 ELECTROCHEMISTRY Substance gaining electron (reduction) 1 under 6 standard 4 conditions 0 1 A substance that lose electron (oxidation) 0 Species is both oxidised and reduced 1 07 EQUILIBRIA 33 B–L Strong acid Weak 35 B–L Strong 36 base Weak 34 Carboxylic acids Nitrogen Proton donor Proton acceptor dissociates completely dissociates partially dissociates completely dissociates partially 37 Dynamic equilibrium 38 Vapour pressure 39 Rate of reaction the forward and reverse reactions occur at the same rate, so there is no change in net concentration. This must occur in a closed system Pressure exerted by vapour on walls & surface of liquid when at equilibrium 08 REACTION KINETICS Change in reactant/product over time 40 Catalyst Substances that increase the rate of chemical reaction by providing an alternative pathway of lower activation 3 0 5 0 1 1 4 2 1 2 energy, but which are left unchanged by the reaction. 41 Heterogeneous Different state 2 42 Homogeneous Same state 1 2 Prepared by Chermaine Lim (2022) Chemistry AS Level Definitions Inorganic Chemistry 43 09 PERIODIC TABLE reacts with both acid and alkali Amphoteric 111 10 GROUP 2 11 GROUP 17 12 NITROGEN & SULFUR Organic Chemistry 44 45 Electrophile Nucleophile 13 INTRODUCTION TO AS ORGANIC CHEMISTRY An atom or group of atoms attracted to an electron-rich Alkenes Halogenoalk anes 46 Functional group site A negative ion or an atom with lone pair electrons attracted to a positively charged ion A group of atom responsible for chemical reactions in a compound 47 Heterolytic fission A compound breaks to form a positive ion and a negative ion. 48 Homolytic fission A bond breaks to form two free radicals. 49 Isomers Chemical species with the same number and types of atoms, but has different properties 50 Structural Same chemical formula but different structural formula isomerism 51 Chain isomerism Different carbon skeleton arrangement 52 Positional same chemical formula, different placement of functional isomerism group Stereoisomerism Same atoms connected to each other, differently 53 arrangement in space 54 Optical isomerism Same structural formula, but have different 3D arrangement/are mirror images due to a chiral centre 55 56 Geometric Same structural formula, but different arrangement in isomerism space due to double bond Chiral centre haloalkanes alcohol 57 Enantiomer An atom in a molecule which is bonded to four different chemical groups, giving rise to optical isomerism. Molecule with a chiral centre which can exist as two optical isomers 58 Hydrocarbon 59 Saturated Alkanes 1 2 0 1 0 0 6 1 0 7 2 2 8 0 14 HYDROCARBONS Compound made up of carbon and hydrogen only 2 Only carbon – carbon single bonds 0 3 Prepared by Chermaine Lim (2022) Chemistry AS Level Definitions 60 Unsaturated 61 Addition Alkenes Presence of at least 1 C = C double bond joining of two molecules to form a single product molecule 62 63 Free radical Addition polymer atom or group of atoms with an unpaired electron 15 HALOGEN COMPOUNDS 16 HYROXY COMPOUNDS 17 CARBONYL COMPOUNDS 18 CARBOXYLIC ACIDS AND DERIVATIVES 19 NITROGEN COMPOUNDS 20 POLYMERISATION Alkenes polymers formed by repeated addition reactions 0 0 2 0 21 ORGANIC SYNTHESIS 4 Prepared by Chermaine Lim (2022)
