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AQA A-Level Chemistry > Definitions - All Topics > Flashcards

Definitions - All Topics Flashcards

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1
Q

Relative Atomic Mass (AR).

A

The average mass of an atom of an element compared to 1/12th of the mass of a 12C atom

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2
Q

Relative Molecular Mass (MR)

A

The average mass of a molecule compared to 1/12th of the mass of a 12C atom

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3
Q

Empirical Formula

A

The simplest ration of atoms of each element in a compound

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4
Q

Atom economy

A

Measure of what proportion of the product of a reaction is desired, and how much is waste

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5
Q

Homologous series

A

A group of chemicals which have similar chemical properties, the same functional group and can be represented by a general formula

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6
Q

Isomers

A

Chemicals with the same molecular formula, but a different structural formula

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7
Q

Structural isomerism

A

Compounds with the same molecular formula, but different structural/skeletal/displayed formula.

Eg of structural isomerism = positional isomerism

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8
Q

Chain isomerism

A

Compounds with the same molecular formula but a different carbon skeleton

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9
Q

Position isomerism

A

Compounds with the same molecular formula and carbon skeleton, but a different position of the same type of functional group

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10
Q

Functional group isomerism

A

Same molecular formula, different functional group

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11
Q

Stereo isomerism

A

When molecules have the same structural formula but a different spatial arrangement of atoms

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12
Q

Enthalpy change of formation

A

The enthalpy change when one mole of a substance is formed from its elements with all products and reactants in their standard states under standard conditions

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13
Q

Enthalpy change of combustion

A

The enthalpy change when one mole of a substance is burned completely in oxygen with all reactants and products in their standard states under standard conditions

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14
Q

Standard conditions

A

298K, 100kPa, 1 moldm^-3 if any solutions involved

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15
Q

Mean bond enthalpy

A

The average heat needed to break one mole of covalent bonds of a molecule in a gaseous state under standard conditions, averaged over a range of compounds

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16
Q

Define “dynamic” (in terms of equilibria)

A

Forward and reverse reactions both take place

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17
Q

Equilibrium

A

Both forward and reverse reactions take place at equal rates. The concentration of all reactants remain constant

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18
Q

Catalyst

A

A substance that increases the rate or reaction without being changed in chemical composition or amount. They work by providing an alternative pathway/reaction route of lower activation energy

19
Q

Activation energy

A

The minimum amount of energy needed for a reaction to occur/for a successful collision

20
Q

Equilibrium constant (Kc)

A

A value calculated from the equilibrium concentrations for a system at constant temperature

Kc = concentration of products/concentration of reactants

21
Q

Oxidation

A

Addition of oxygen or loss of electrons to a substance

22
Q

Reduction

A

Removal of oxygen or addition of electrons to a substance

23
Q

Disproportionation

A

When atoms of the same element are simultaneously oxidised and reduced

24
Q

Reducing agent

A

A species which aids the reduction of another species by donating the electrons which the other species gains. The reducing agent’s oxidation state will become more positive (more oxidised)

25
Q

Oxidising agent

A

A species which aids the oxidation of another species by accepting the electrons that the other species loses. The oxidising agent’s oxidation state will become less positive/more negative (more reduced)

26
Q

Isotopes

A

Atoms of the same element with the same atomic number but a different mass number. (same no. of protons and electrons, diff. no. of neutrons)

27
Q

Atomic number

A

The number of protons in the atom nucleus (aka protonic no.)

28
Q

Mass number

A

The number of protons AND neutrons in the nucleus of an atom

29
Q

1st ionisation energy

A

The energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms

30
Q

2nd ionisation energy

A

The amount of energy required to remove an electron from each ion in 1 mole of gaseous 1+ ions

31
Q

Dative/Coordinate bond

A

A covalent bond whereby the pair of electrons originate from one atom

32
Q

Polar molecules

A

Molecules whereby the polar bonds combine in such a way some parts are more negative/positive

33
Q

Electronegativity

A

The power of an atom to attract the pair of electrons in a covalent bond

34
Q

Saturated

A

When a molecule contains only carbon-carbon single bonds (no double bonds)

35
Q

Hydrocarbon

A

A molecule containing a hydrogen and a carbon only

36
Q

Hydrolysis

A

Splitting molecules using water

37
Q

Nucleophile

A

An electron pair donator

38
Q

Electrophile

A

An electron pair acceptor

39
Q

Addition Polymerisation

A

Formation of long chain molecules from lots of small molecules joining together with no other products

40
Q

Plasticisers

A

Small molecules that get between the polymer chains, allowing them to slide past each other. This makes the chains more flexible

41
Q

What is a free radical?

A

An atom or species with an unpaired electron

42
Q

Define standard enthalpy of atomisation

A

The enthalpy change when mole of gaseous atoms is formed from the element in its standard state under standard conditions

43
Q

Define first electron affinity

A

The enthalpy change when one mole of gaseous atoms is converted into one mole of gaseous ions, each with a single negative charge, under standard conditions

44
Q

Define second electron affinity

A

The enthalpy change when mole of electrons is added to one mole of gaseous ions, each with a single negative charge to form one mole of gaseous ions each with 2 negative charges

AQA A-Level Chemistry (36 decks)

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