Off By Heart Definitions Spring Test

Question 1

Sigma bond

Answer 1

Overlap of orbitals directly between bonding atoms

Question 2

Homolytic fission

Answer 2

Breaking of a covalent bond where each atom retains one of the shared pair of electrons

Question 3

Radical

Answer 3

A species with an unpaired electron

Question 4

Pi bond

Answer 4

The sideways overlap of adjacent p orbitals above and below the bonding carbon atoms, there is restricted rotation

Question 5

Stereoisomerism

Answer 5

Compounds with the same structural formula but different arrangements in space

Question 6

E/Z isomerism

Answer 6

Restricted rotation around the pi bond and 2 different groups attached to each carbon atom of the C-C double bond

Question 7

Cis-trans isomerism

Answer 7

A case of E/Z isomerism where 2 of the substituent groups attached to the C atoms of the C-C double bond are a H

Question 8

Electrophile

Answer 8

An electron pair acceptor (cation or delta positive whether induced or permanent)

Question 9

Heterolytic fission

Answer 9

A covalent Bond breaks and one of the atoms retains the shared pair of electrons forming an anion and a cation

Question 10

Addition polymerisation

Answer 10

C-c double bond breaks open enabling free bonds to link with another one, forming a chain

Question 11

Conditions for hydrogenation

Answer 11

Nickel catalyst, 150C

Question 12

Hydration conditions

Answer 12

Phosphoric acid (H3PO4) and 300C

Question 13

Isotope

Answer 13

Atoms of the same element with different amounts of neutrons and different masses

Question 14

Relative isotopic mass

Answer 14

The mass of an isotope relative to the mass of 1/12 an atom of Carbon-12

Question 15

Relative atomic mass

Answer 15

The weighted mean mass of atoms of an element relative the the mass of 1/12 an atom of carbon-12

Question 16

Hydrated crystal

Answer 16

Water molecules are part of the crystalline structure

Question 17

Water of crystallisation

Answer 17

The water within the structure of a hydrated crystal

Question 18

Orbital

Answer 18

A region around the nucleus that can hold up to 2 electrons with opposite spins

Question 19

Ionic bonding

Answer 19

The electrostatic attraction between positive and negative ions

Question 20

Covalent bonding

Answer 20

The strong electrostatic attraction between the shared pair of electrons and the nuclei of the bonded atoms

Question 21

Electronegativity

Answer 21

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

Question 22

Hydrogen bonding

Answer 22

The intermolecular bonds between N, O, F and the H of -ON, -OH, or Hf

Question 23

1st ionisation energy

Answer 23

The energy required to remove 1 electron from each atom of 1 mole of gaseous atoms to from 1 mole of gaseous 1+ ions

Question 24

Metallic bonding

Answer 24

The strong electrostatic attraction between cations and delocalised electrons

Question 25

Structural isomers

Answer 25

Compounds with the same molecular formula but different structural formulae

Question 26

Distillation

Answer 26

evaporation followed by condensation, which allows the most volatile component to be separated.

Question 27

Heating under reflux

Answer 27

a process of continuous evaporation and condensation, which prevents the volatile components from escaping

Question 28

Average bond enthalpy

Answer 28

A measure of covalent bond strength

Question 29

Disproportionation

Answer 29

Oxidation and reduction of the same element

Question 30

Structural isomer

Answer 30

Compounds with the same molecular formula but different structural formulae

Question 31

Nucleophile

Answer 31

An electron pair donor

Question 32

Enthalpy change of reaction

Answer 32

The enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions with all reactants and products in their standard states

Question 33

Enthalpy change of formation

Answer 33

The enthalpy change that takes place when one mole of a compound is formed from its elements under standard conditions with all reactants and products in their standard state.

Question 34

Enthalpy change of combustion

Answer 34

The enthalpy change that occurs when 1 mole of a substance reacts completely with oxygen under standard conditions with all reactants and products in their standard state

Question 35

Enthalpy change of neutralisation

Answer 35

The enthalpy change that accompanies the neutralisation of an acid by a base to form 1 mole water under standard conditions with all reactants and products in their standard state

Question 36

Average bond enthalpy

Answer 36

Breaking of 1 mol bonds in gaseous molecules

Question 37

Homogeneous catalyst

Answer 37

Catalyst same state as reactants Eg. Hydration of alkenes

Question 38

Heterogeneous catalysts

Answer 38

Catalyst different state to reactants Eg. Haber process

Question 39

Aliphatic

Answer 39

Straight/ branched chain

Question 40

Alkyl

Answer 40

CnH2n+1

Question 41

Alicyclic

Answer 41

Non-aromatic ring

Question 42

Aromatic

Answer 42

Containing a benzene ring

Question 43

Electron shielding

Answer 43

Inner electrons repel outer electrons reducing the attraction between the nucleus and outer shell electrons