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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
Kc
measure of the position of equilibrium | Kc = [C]^c [D]^d ÷ [A]^a [B]^b
26
free energy change (GIBBS)
∆G = ∆H - T∆S -reaction feasible when ∆G is 0 or neg
27
half life
time taken for the concentration of a reactant to decrease by half
28
heterogenous catalyst
catalyst + reactants have different physical states
29
homogenous catalyst
catalyst + reactants have same physical states
30
heterolytic fission
the breaking of a covalent bond w/ both of the bonded e- going to one of the species, forming a cation + anion
31
homolytic fission
the breaking of a covalent bond where 1 e- goes to each atom forming two radicals
32
radical
species w/ an unpaired e-
33
ionic bonding
the electrostatic attraction between pos + neg ions
34
Kw / ionic product of water
Kw = [H+ (aq)] [OH- (aq)]
35
isotopes
atoms of the same elements w/ different numbers of neutrons
36
Le Chatelier's Principal
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
metallic bond
the electrostatic attraction between pos metal ions + delocalised e-
38
neutralisation
a reaction in which an acid and base react together to form a salt
39
oxidation
loss of e- | incr. in oxidation number
40
oxidising agent
a reagent that oxidises (takes e- from) another species
41
π bond
a bond formed from the overlap of P orbitals, w/ e- density above + below the plane
42
% yield
(actual yield in mol ÷ theoretical yield in mol) x100
43
pH
pH= -log([H+ (aq)])
44
rate of reaction
the change in concentration of a reactant / product over a given time
45
rate determining step
slowest step in the reaction mechanism of a multi-step reaction
46
redox reaction
a reaction involving oxidation + reduction
47
reducing agent
a species that reduces (adds an e-) to another species
48
reduction
gain of e- | decr. in oxidation number
49
retention time
the time taken in gas chromatography for the component to pass from the column inlet to the detector
50
Rf value
Rf value = distance moved by ÷ distance moved by solvent
51
standard conditions
``` 100 kPa 298 K (25ºc) (for reactions w/ aq solutions = 1 mol dm-3) ```
52
standard electrode potential (E^⊖)
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
strong acid
an acid that fully dissociates
54
weak acid
an acid that partially dissociates
55
transition elements
D block elements forming one or more stable ions with incomplete D orbitals
56
complex ion
a central metal ion co-ordinately bonded to one or more molecule / negative ion
57
ligand
a molecule/ion that donates a pair of e- to a central metal ion to form a co-ordinate bond
58
co-ordination number
the total number of co-ordinate bonds formed between the central metal ion + any ligands
59
ligand subsitution
when one ligand is replaced by another
60
lattice enthalpy
the energy change that takes place when one mole of an ionic compound is formed from it constituent gaseous ions, under standard conditions
61
enthalpy of atomisation
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
1st electron affinity
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
2nd electron affinity
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
enthalpy change of solution
the energy change when 1 mol of a solute dissolved in a solvent, under standard conditions
65
enthalpy of combustion
the energy required to completely combust 1 mole of a substance with O2 under standard conditions
66
first ionisation energy
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
second ionisation energy
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
enthalpy of hydration
the energy required to dissolve 1 mole of gaseous ions in water to form 1 mole of aq ions under standard conditions
69
enthalpy of neutralisation
the energy required to form 1 mol of H2O (l) by an acid-base reaction under standard conditions
70
enthalpy of formation
the energy required to form 1 mole of a compound from its constituent elements under standard conditions
71
relative isotopic mass
mass of an isotope compared to 1/12 of carbon 12
72
salt
when the H+ in an acid is replaced by a positive ion (i.e metal ion / ammonium ion)
73
relative atomic mass
the average mass of an isotope compared to 1/12 of carbon 12
74
orbital
a region within an atom that can hold up to a maximum of 2 e- with opposite spin
75
electronegativity
the ability of an atom to attract an e- in a covalent bond

OCR A CHEM (9 decks)

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