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OCR A CHEM > DEFINITIONS > Flashcards

DEFINITIONS Flashcards

1
Q

ATOM ECONOMY

A

(∑mr of desired product ÷ ∑mr of all products) x 100

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2
Q

STRUCTURAL ISOMER

A

compounds w/ the same mr

but different structural formular

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3
Q

STEREOISOMER

A

compounds w/ the same structural formula

but atoms have different arrangements in space

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4
Q

ACID

A

species that releases H+ in aq solution

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5
Q

Ka

A

Ka = [H+(aq)] [A- (aq)] ÷ [HA (aq)]

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6
Q

acid-base pair

A

pair of two species that transform into eachother by the gain / loss of H+

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7
Q

activation energy

A

the minimum amount of energy required to start a reaction by breaking the bond

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8
Q

adsorption

A

when a gas / liquid / solute is held to the surface of a solid

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9
Q

alicyclic

A

C ring that is not aromatic

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10
Q

anion

A

negatively charged ion w/ more e- than H+

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11
Q

atomic number

A

number of protons in nucleus of an atom

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12
Q

average bond enthalpy

A

the average energy change when breaking 1 mol of a given type of bond by homolytic fission in molecules of a gaseous species

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13
Q

AVOGADRO’S CONSTANT

A

6.02 x10^23

the number of atoms per mole of the C12 isoptope

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14
Q

base

A

a compound that neutralises and acid to form a salt

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15
Q

Brønsted-Lowry Acid

A

H+ donor

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16
Q

Brønsted-Lowry Base

A

H+ acceptor

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17
Q

buffer solution

A

a system that minimises the change in pH on addition of a small amount of acid / base

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18
Q

catalyst

A

a substance that incr. rate of reaction without being used up in the process

provides an alternative pathway for the reaction with a lower activation energy

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19
Q

chiral carbon

A

a C attached to 4 different groups/atoms

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20
Q

conjugate acid

A

a species that releases a proton to form a conjugate base

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21
Q

conjugate base

A

a species that accepts a proton to form a conjugate acid

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22
Q

covalent bond

A

the strong electrostatic force of attraction between a shared pair of e- + the nuclei of bonded atoms

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23
Q

dative covalent

A

a shared pair of e- in which the bonded pair has been provided ONLY by one of the bonded atoms

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24
Q

optical isomers / enantiomers

A

stereoisomers that are non-superimposable mirror images of one another

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25
Q

Kc

A

measure of the position of equilibrium

Kc = [C]^c [D]^d ÷ [A]^a [B]^b

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26
Q

free energy change (GIBBS)

A

∆G = ∆H - T∆S

-reaction feasible when ∆G is 0 or neg

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27
Q

half life

A

time taken for the concentration of a reactant to decrease by half

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28
Q

heterogenous catalyst

A

catalyst + reactants have different physical states

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29
Q

homogenous catalyst

A

catalyst + reactants have same physical states

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30
Q

heterolytic fission

A

the breaking of a covalent bond w/ both of the bonded e- going to one of the species, forming a cation + anion

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31
Q

homolytic fission

A

the breaking of a covalent bond where 1 e- goes to each atom forming two radicals

32
Q

radical

A

species w/ an unpaired e-

33
Q

ionic bonding

A

the electrostatic attraction between pos + neg ions

34
Q

Kw / ionic product of water

A

Kw = [H+ (aq)] [OH- (aq)]

35
Q

isotopes

A

atoms of the same elements w/ different numbers of neutrons

36
Q

Le Chatelier’s Principal

A

when a system in dynamic equilibrium is subject to external changes, the system readjusts itself to minimise the effect of the change + restore the equilibrium

37
Q

metallic bond

A

the electrostatic attraction between pos metal ions + delocalised e-

38
Q

neutralisation

A

a reaction in which an acid and base react together to form a salt

39
Q

oxidation

A

loss of e-

incr. in oxidation number

40
Q

oxidising agent

A

a reagent that oxidises (takes e- from) another species

41
Q

π bond

A

a bond formed from the overlap of P orbitals, w/ e- density above + below the plane

42
Q

% yield

A

(actual yield in mol ÷ theoretical yield in mol) x100

43
Q

pH

A

pH= -log([H+ (aq)])

44
Q

rate of reaction

A

the change in concentration of a reactant / product over a given time

45
Q

rate determining step

A

slowest step in the reaction mechanism of a multi-step reaction

46
Q

redox reaction

A

a reaction involving oxidation + reduction

47
Q

reducing agent

A

a species that reduces (adds an e-) to another species

48
Q

reduction

A

gain of e-

decr. in oxidation number

49
Q

retention time

A

the time taken in gas chromatography for the component to pass from the column inlet to the detector

50
Q

Rf value

A

Rf value = distance moved by ÷ distance moved by solvent

51
Q

standard conditions

A 
100 kPa
298 K (25ºc)
(for reactions w/ aq solutions = 1 mol dm-3)
52
Q

standard electrode potential (E^⊖)

A

the e.m.f of a half cell compared to a standard hydrogen half-cell, measured at 100 kPa, 298 K, with solutions of 1 mol dm-3

53
Q

strong acid

A

an acid that fully dissociates

54
Q

weak acid

A

an acid that partially dissociates

55
Q

transition elements

A

D block elements forming one or more stable ions with incomplete D orbitals

56
Q

complex ion

A

a central metal ion co-ordinately bonded to one or more molecule / negative ion

57
Q

ligand

A

a molecule/ion that donates a pair of e- to a central metal ion to form a co-ordinate bond

58
Q

co-ordination number

A

the total number of co-ordinate bonds formed between the central metal ion + any ligands

59
Q

ligand subsitution

A

when one ligand is replaced by another

60
Q

lattice enthalpy

A

the energy change that takes place when one mole of an ionic compound is formed from it constituent gaseous ions, under standard conditions

61
Q

enthalpy of atomisation

A

the energy change that takes place when 1 mole of gaseous atoms are formed from the element in its standard state, under standard conditions

62
Q

1st electron affinity

A

the enthalpy change that takes place, under standard conditions, when 1 e- is added to each atom in 1 mol of gaseous atoms to form 1 mol of gaseous 1- ions, under standard conditions

63
Q

2nd electron affinity

A

the enthalpy change that takes place, under standard conditions, when 1 e- is added to each atom in 1 mol of gaseous atoms to form 1 mol of gaseous 2- ions, under standard conditions

64
Q

enthalpy change of solution

A

the energy change when 1 mol of a solute dissolved in a solvent, under standard conditions

65
Q

enthalpy of combustion

A

the energy required to completely combust 1 mole of a substance with O2 under standard conditions

66
Q

first ionisation energy

A

the energy required to remove 1 e- from each atom in 1 mole of gaseous atoms to form 1 mole of unipositive gaseous ions, under standard conditions

67
Q

second ionisation energy

A

the energy required to remove 1 e- from each 1- ion in 1 mole of gaseous 1- ion to form 1 mole of bi-positive gaseous ions , under standard conditions

68
Q

enthalpy of hydration

A

the energy required to dissolve 1 mole of gaseous ions in water to form 1 mole of aq ions under standard conditions

69
Q

enthalpy of neutralisation

A

the energy required to form 1 mol of H2O (l) by an acid-base reaction under standard conditions

70
Q

enthalpy of formation

A

the energy required to form 1 mole of a compound from its constituent elements under standard conditions

71
Q

relative isotopic mass

A

mass of an isotope compared to 1/12 of carbon 12

72
Q

salt

A

when the H+ in an acid is replaced by a positive ion (i.e metal ion / ammonium ion)

73
Q

relative atomic mass

A

the average mass of an isotope compared to 1/12 of carbon 12

74
Q

orbital

A

a region within an atom that can hold up to a maximum of 2 e- with opposite spin

75
Q

electronegativity

A

the ability of an atom to attract an e- in a covalent bond

OCR A CHEM (9 decks)

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