chemistry definitions

Question 1

define nucleophile

Answer 1

an e- pair donor

Question 2

define electrophile

Answer 2

an e- pair acceptor

Question 3

define free radicals

Answer 3

species with an unpaired e-

Question 4

define homologous series

Answer 4

family of similar compounds with the same functional grp and similar chemical properties, with successive members differing by the addition of a CH2 grp

Question 5

define functional grp

Answer 5

part of the compound that determines its chemical characteristics

Question 6

define orbital

Answer 6

region around the nucleus that can hold up to 2 e-s with opposite spins

Question 7

define enthalpy change of combustion

Answer 7

enthalpy change when 1 mol of substance combusts completely with O2

Question 8

define enthalpy change of formation

Answer 8

enthalpy change when 1 mol of compound formed form its elements

Question 9

define enthalpy change of neutralisation

Answer 9

enthalpy change when 1 mol of water formed from reaction between acid and base

Question 10

define enthalpy change of reaction

Answer 10

overall energy taken in/given to surroundings when reactants react together

Question 11

define structural isomer

Answer 11

same molecular formula, diff. structural formula

Question 12

define aromatic compound

Answer 12

compounds containing benzene ring

Question 13

define alicyclic compound

Answer 13

aliphatic compound arranged in non-aromatic rings (cyclic structure without benzene ring)

Question 14

define aliphatic compound

Answer 14

compound containing C and H atoms joined in straight or branched chains / in non-aromatic rings

Question 15

define heterlotytic fission

Answer 15

when covalent bond breaks unevenly (1 atom takes both of the shared e-s), forming +tive and -tive ions

Question 16

define hommolytic fission

Answer 16

when covalent bond breaks evenly, each atom takes 1 e- from the shared pair, forming 2 free radicals

Question 16

define curly arrows

Answer 16

shows the movement of an e- pair

Question 17

define homogeneous catalyst

Answer 17

catalyst in the same physical state (phase) as reactants, finds alternative reaction pathway with lower activation energy

Question 17

define heterogeneous catalyst

Answer 17

catalyst in the diff. physical state (phase) as reactants, finds alternative reaction pathway with lower activation energy

Question 18

define polymerisation

Answer 18

monomers joined together to long repeating units (polymer)

Question 19

define electronegativity

Answer 19

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

Question 20

define le chatielier’s principle

Answer 20

The position of the equilibrium of a system changes to minimise the effect of any imposed change in conditions

Question 21

define precipitate

Answer 21

a solid formed by a change in a solution that decreases solubility of a solid

Question 22

define disproportionation

Answer 22

a reaction in which the same element is both oxidised and reduced

Question 23

define dynamic equilibrium

Answer 23

forward reaction happening at same rate as backwards reaction, concs of both reactants + products remain constant

Question 24

define an arene

Answer 24

an aromatic compound (contains a benzene ring)

Question 25

define a carbocation

Answer 25

positively charged carbon atoms with only three covalent bonds instead of four

Question 26

define stoichiometry

Answer 26

the relative quantities of substances in a reaction.

Question 27

define markownicoff’s law

Answer 27

When a hydrogen halide reacts with an unsymmetrical alkene the hydrogen of the hydrogen halide bonds to the C atom with the most H atoms already bonded

Question 28

define hess’ law

Answer 28

the ​enthalpy change​of a reaction is ​independent​of the ​route​taken

Question 29

define primary alcohol

Answer 29

the carbon atom bonded to the -OH group is attached to ONE other carbon atom (or alkyl group)

Question 30

define secondary alcohol

Answer 30

The carbon atom the -OH group is bonded to is bonded to TWO alkyl groups

Question 31

define tertiary alcohol

Answer 31

The carbon atom the -OH group is bonded to is bonded to three alkyl groups.

Question 32

define average bond enthalpy

Answer 32

the average amount of energy needed to break a specific type of bond

Question 33

what are the standard conditions?

Answer 33

1 atm (100KPa)

25 degrees celcius/298 K

Question 34

define fragmentation

Answer 34

a type of chemical dissociation, in which the removal of the electron from the molecule results in ionization