definitions

Question 1

Define alicyclic.

Answer 1

Alicyclic - compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings

Question 2

Define alicyclic.

Answer 2

Alicyclic - aliphatic compound arranged in non-aromatic rings with/without side chains

Question 3

Define aromatic.

Answer 3

Aromatic - compound containing a benzene ring

Question 4

Define cis-trans isomerism.

Answer 4

Cis-trans isomerism - special case of E/Z isomerism in which two of the substituent groups attached to each carbon atom of the C=C group are the same

Question 5

Define curly arrow.

Answer 5

Curly arrow - movement of a pair of electrons

Question 6

Define delocalised electrons.

Answer 6

Delocalised electrons - electrons that are shared between more than two atoms

Question 7

Define electrophile.

Answer 7

Electrophile - electron pair acceptor, attracted to electron-rich region

Question 8

Define E/Z isomerism.

Answer 8

E/Z isomerism - type of stereoisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of the restricted rotation of the C=C bond

Question 9

Define heterolytic fission.

Answer 9

Heterolytic fission - when a bond breaks & one bonding atom receives both electrons from bonded pair

Question 10

Define homologous series.

Answer 10

Homologous series - series of organic compounds having the same functional group but with each successive member differing by CH2

Question 11

Define homolytic fission.

Answer 11

Homolytic fission - when a bond breaks and each bonding atom receives one electron from bonded pair, forming two radicals

Question 12

Define hydrocarbon.

Answer 12

Hydrocarbon - compound of hydrogen and carbon only

Question 13

Define nucleophile.

Answer 13

Nucleophile - electron pair donor, attracted to electron-deficient regions

Question 14

Define optical isomerism.

Answer 14

Optical isomerism - stereoisomerism that are non-superimposable mirror images of each other

Question 15

Define radical.

Answer 15

Radical - species with an unpaired electron

Question 16

Define reflux.

Answer 16

Reflux - continual boiling and condensing of a reaction mixture back to original container to ensure that the reaction takes place without the contents of the flask boiling dry

Question 17

Define saturated.

Answer 17

Saturated - containing single carbon-carbon bonds only

Question 18

Define stereoisomerism.

Answer 18

Stereoisomerism - compounds have same structural formula but a different arrangement of atoms in space

Question 19

Define structural isomerism.

Answer 19

Structural isomerism - compounds with same molecular formula but different structural formulae

Question 20

Define unsaturated.

Answer 20

Unsaturated - presence of multiple carbon-carbon bonds (double/triple/aromatic ring)

Question 21

Define isotopes.

Answer 21

Isotopes - atoms of same element with different numbers of neutrons and different masses

Question 22

Define relative atomic mass.

Answer 22

Relative atomic mass - weighted mean mass of an atom compared with 1/12th mass of carbon-12

Question 23

Define orbital.

Answer 23

Orbital - region around the nucleus that can hold up to two electrons with opposite spins

Question 24

Define covalent bond.

Answer 24

Covalent bond - strong electrostatic attraction between shared pair of electrons and nuclei of bonded atoms

Question 25

Define ionic bonding.

Answer 25

Ionic bonding - electrostatic attraction between positive and negative ions

Question 26

Define metallic bonding.

Answer 26

Metallic bonding - strong electrostatic attraction between cations and delocalised electrons

Question 27

Define electronegativity.

Answer 27

Electronegativity - ability of an atom to attract the bonding electrons in a covalent bond

Question 28

Define first ionisation energy.

Answer 28

First ionisation energy - energy required to remove 1 mol of electrons from 1 mol of gaseous atoms to form 1 mol of 1+ ions

Question 29

Define standard enthalpy change of reaction.

Answer 29

∆rH˚- enthalpy change associated with a stated equation, under standard conditions

Question 30

Define standard enthalpy change of combustion.

Answer 30

∆cH˚ - enthalpy change when 1 mol of a substance undergoes complete combustion under standard conditions

Question 31

Define standard enthalpy change of formation.

Answer 31

∆fH˚ - enthalpy change when 1 mol of a compound forms from its elements in their standard states, under standard conditions

Question 32

Define standard enthalpy change of neutralisation.

Answer 32

∆neutH˚ - enthalpy change when 1 mol of water forms from neutralisation, under standard conditions

Question 33

Define lattice enthalpy.

Answer 33

∆LEH˚ - enthalpy change that accompanies the formation of 1 mol of ionic lattice from gaseous ions

Question 34

Define standard enthalpy change of atomisation.

Answer 34

∆atH˚ - enthalpy change that takes place when 1 mol of gaseous atoms forms from the element in its standard state

Question 35

Define first electron affinity.

Answer 35

∆EA1H˚ - enthalpy change that takes place when one electron is added to each atom in 1 mol of gaseous atoms to form 1 mol of gaseous 1- ions

Question 36

Define enthalpy change of solution.

Answer 36

∆solH˚ - enthalpy change that takes place when 1 mol of a compound is completely dissolved in water under standard conditions

Question 37

Define enthalpy change of hydration.

Answer 37

∆hydH˚ - enthalpy change that takes place when 1 mol of isolated gaseous ions is dissolved in water forming 1 mol of aqueous ions under standard conditions

Question 38

Define entropy.

Answer 38

Entropy - measure of dispersal of energy in a system, greater value means more disordered system

Question 39

Define rate of reaction.

Answer 39

Rate of reaction - speed at which reactants are being turned into products

Question 40

Define activation energy.

Answer 40

Ea - minimum energy required for a reaction to take place

Question 41

Define catalyst.

Answer 41

Catalyst - substance that increases the rate of a chemical reaction without being used up in the process by providing an alternative route for the reaction with lower activation energy

Question 42

Define half-life.

Answer 42

Half-life - time taken for concentration of a reactant to decrease by half

Question 43

Define rate-determining step.

Answer 43

Rate-determining step - slowest step in the reaction mechanism of a multi-step reaction, rate equation shows its stoichiometric ratios

Question 44

Define dynamic equilibrium.

Answer 44

Dynamic equilibrium - equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction and concentrations do not change

Question 45

Define Brønsted-Lowry acid.

Answer 45

Brønsted-Lowry acid - species that donates a proton

Question 46

Define Brønsted-Lowry base.

Answer 46

Brønsted-Lowry base - species that accepts a proton

Question 47

Define alkali.

Answer 47

Alkali - type of base that dissolves in water, forming hydroxide ions

Question 48

Define buffer.

Answer 48

Buffer - system that minimises pH changes on addition of small amounts of acid or base

Question 49

Define oxidising agent.

Answer 49

Oxidising agent - species that oxidises (takes electron from) another species

Question 50

Define reducing agent.

Answer 50

Reducing agent - species that reduces (adds electrons to) another species

Question 51

Define disproportionation.

Answer 51

Disproportionation - oxidation and reduction of the same element

Question 52

Define standard electrode potential.

Answer 52

E˚ - electromagnetic field across a half-cell compared with standard hydrogen half-cell measured at standard conditions

Question 53

Define transition elements.

Answer 53

Transition elements - d-block elements that have an ion with an incomplete d-sub-shell

Question 54

Define complex ion.

Answer 54

Complex ion - transition metal ion bonded to ligands by coordinate bonds (dative covalent bonds)

Question 55

Define coordination number.

Answer 55

Coordination number - total number of coordinate bonds formed between a central metal ion and ligands

Question 56

Define bidentate ligand.

Answer 56

Bidentate ligand - ligand with two lone pairs, both of which can bond to central metal ion