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GCSE OCR Chemistry > Definitions > Flashcards

Definitions Flashcards

1
Q

Relative atomic mass

A

Weighted mean mass of an atom of an element, compared to 1/12 of the mass of an atom of carbon-12.

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2
Q

Relative isotopic mass

A

Mass of an atom of an isotope of an element compared to 1/12 of the mass of an atom of carbon-12.

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3
Q

Relative formula mass

A

Mass of 1 unit relative to 1/12 mass of carbon-12.

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4
Q

Relative molecular mass

A

Mass of one molecule relative to 1/12 mass of carbon-12.

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5
Q

Molar mass

A

Mass of 1 mole, same number as relative mass.

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6
Q

Mole

A

Unit of amount of substance.

One is roughly Avogadro’s constant (same number as the atoms in 12g of carbon-12).

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7
Q

Empirical formula

A

Simples whole number ratio of atoms in a molecular.

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8
Q

Molecular formula

A

Shows the number of atoms of each element in a molecule.

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9
Q

Atom economy

A

A measure of what proportion of the products of a reaction is the desired product and how much is waste.

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10
Q

Ionic bond

A

Strong electrostatic attraction between anions and cations.

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11
Q

Molecule

A

2 or more atoms covalentally bonded.

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12
Q

Covalent bonding

A

Strong electrostatic attration between a shared pair of electrons and the nuclei of the bonded atoms.

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13
Q

Dative covalent bond

A

Shared pair of electrons which has been provided by one of the bonding atoms only.

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14
Q

Orbital

A

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

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15
Q

Spin pairing

A

If there are 2 electrons in an orbital, they must ‘spin’ in opposite directions.

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16
Q

Theoretical yield

A

Mass of product that should be formed ina chemical reaction.

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17
Q

Oxidising agent

A

Accept electrons and gets reduced.

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18
Q

Reducing agent

A

Donates electrons and gets oxidised.

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19
Q

Electronegativity

A

Ability of an atom to attract the bonding electrons in a covalent bond.

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20
Q

Dipole

A

The difference in charge between the 2 atoms caused by a shift in electron density in the bond.

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21
Q

London forces

A

An uneven distribution of electrons causes one side of the atom to be partially +ve and the other to be partially -ve.

Creates a temporary dipole.

This induces a dipole in another side of the atom.

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22
Q

Permanent dipole-dipole interactions

A

IMF that exist because the difference in electronegativities in a polar bond which causes a weak electrostatic attraction between molecules.

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23
Q

Hydrogen bonding

A

Only happens when hydrogen is covalently bonded to fluorine, nitrogen and oxygen.

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24
Q

1st ionisation energy

A

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

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25
Q

Shielding

A

Lessening of the pull of the outer electron caused by the electrons between the nucleus and the outer electron.

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26
Q

Charge density

A

Amount of charge in relation to the size of an ion.

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27
Q

Disproportionation

A

A single element is simultaneously oxidised and reduced.

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28
Q

Enthalpy change

A

Heat energy transferred in a reaction at constant pressure.

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29
Q

Standard enthalpy change of reaction

A

Enthalpy change when a reaction occurs in the molar quantities shown in the chemical equation, under standard conditions with all reactants and products in their standard states.

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30
Q

Standard enthalpy change of formation

A

Enthalpy change when 1 mole of a compound is formed from its elemetns in their standard states under standard conditions.

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31
Q

Standard enthalpy change of combustion

A

Enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions with all reactants and products in their standard states.

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32
Q

Standard enthalpy change of neutralisation

A

Enthalpy change when solutions of an acid and an alkali react together to form 1 mole of water, under standard conditions.

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33
Q

Hess’ Law

A

Total enthalpy change of a reaction is always the same, no matter which route is taken.

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34
Q

Catalyst

A

A substance that increases the rate of reaction by providing an alternative reaction pathway with lower activation energy.

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35
Q

Activation energy

A

The minimum amount of KE that particles need for a successful collision.

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36
Q

Reaction rate

A

How fast a reaction takes place.

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37
Q

Structural formula

A

Minimum detail that shows the arrangement of the atoms in a molecule.

38
Q

Displayed formula

A

Shows the relative positioning of atoms and the bonds between them.

39
Q

Homologous series

A

Series of organic compounds having the same functional group with successive members differing by CH2.

40
Q

Functional group

A

Group of atoms responsible for the characteristic reactions of a compound.

41
Q

Structural isomers

A

Same molecular formula; different bonding patterns of atoms.

42
Q

Chain isomers

A

Isomers caused by different arrangements of the C-atoms to form straight or branched chains.

43
Q

Positional isomers

A

Isomers caused by different POSITIONS of the SAME functional groups.

44
Q

Functional group isomers

A

Isomers caused by different functional groups.

45
Q

Stereoisomers

A

Isomers resulting from different spatial arrangements of some atoms with the same structural formula.

46
Q

Optical isomers

A

4 different groups bonded to a central (chiral) C atom such that one isomer is the non-identical mirror image of each other.

47
Q

Geometrical isomers

A

A different arrangement of the SAME group about a C=C group.

48
Q

Acids

A

Proton donors which release H+ ions when mixed with water (in aqueous solution).

49
Q

Alkalis

A

Bases that are soluble in water and release OH- ions in aqueous solution.

50
Q

Anhydrous salt

A

Salt that doesn’t contain any water of crystallisation.

51
Q

Base

A

A substance that removes H+ ions from an aqueous solution (proton acceptor).

52
Q

Complete combustion

A

Burning a substance completely in an excess of O2.

Burning a hydrocarbon produces CO2 + H2O only.

53
Q

Concentration

A

A measure of how many moles (or grams) of a substance are dissolved in a volume of solution.

54
Q

Dehydration reaction

A

Reaction in which water is eliminated from an organic molecule.

55
Q

Distillation

A

A technique used to separate liquids with different b.p.

56
Q

Giant covalent lattice / macromolecular structure

A

A structure consisting of a huge network of covalently bonded atoms.

57
Q

Giant ionic lattice structure

A

A repeated structure made up of oppositely charged ions strongly attracted to each other in all directions.

58
Q

Giant metallic lattice structure

A

A regular structure consisting of closely packed metal cations in a sea of delocalised electrons.

59
Q

Greenhouse effect

A

Absorption and re-emission of IR radiation by greenhouse gases in the atmosphere.

60
Q

Greenhouse gas

A

Gas that absorbs and emits IR radiation and contributes to the greenhouse effect.

61
Q

Incomplete combustion

A

Burning a substance in poor supply of oxygen.

Burning a hydrocarbon produces CO + H2O.
And sometimes C and CO2.

62
Q

Ionisation

A

Removal of one or more electrons from an atom or molecule, resulting in an ion forming.

63
Q

Isotope

A

1 of 2 or more forms of an element with the same number of protons but different numbers of neutrons and masses.

64
Q

Isotopic abundance

A

Relative amount of a particular isotope occurring in a sample of an element.

65
Q

Mass spectrometry

A

An analytical technique used to find the structure of a molecule by measuring the masses of the ions it produces when it’s bombarded with electrons.

66
Q

Mass spectrum

A

Chart produced by a mass spectrometer.

67
Q

Haloalkane

A

Alkane with at least 1 halogen atom in place of a H2 atom.

68
Q

Nomenclature

A

Naming organic compounds.

69
Q

Oxidation number

A

The total number of electrons an element has donated or accepted.

70
Q

Percentage yield

A

Amount of product that is actually obtained during a reaction.

71
Q

Periodicity

A

Trends in physical and chemical properties of elements as you go across the periodic table.

72
Q

Pi bond

A

Type of bond formed when 2 p orbitals overlap sideways.

73
Q

Polar bond

A

A covalent bond where a difference in electronegativity has caused a shift in electron density in the bond.

74
Q

Radical

A

A particle with an unpaired electron.

74
Q

Percentage yield

A

Amount of product that is actually obtianed during a reaction.

75
Q

Oxidising agent

A

A chemical that accepts electrons and gets reduced.

76
Q

Reducing agent

A

A chemical that donates electrons and gets oxidised.

77
Q

Saturated hydrocarbon

A

Hydrocarbon where all the carbon-carbon bonds are single bonds.

78
Q

Simple molecular structure

A

A compound with strong covalent bonds within its molecules but weak London forces between its molecules.

79
Q

Spin

A

Momentum possessed by an electron.

80
Q

Standard conditions

A

101 kPa / 1 atm.

25 °C / 298 K.

81
Q

Successive ionisation energy

A

The energy needed to remove 1 mole of each subsequent electron from each ion in 1 mole of positively charged gaseous ions.

82
Q

Theoretical yield

A

Mass of product that should be formed in a chemical reaction if no reactant or product is ‘lost’.

83
Q

Unsaturated hydrocarbon

A

A hydrocarbon with 1 or more carbon-carbon double bonds, carbon-carbon triple bonds or an aromatic group.

84
Q

Titration

A

An experiment used to find the concentration of a solution.

Involves gradually adding one solution to a known volume of another until the reaction between the 2 is complete.

85
Q

Titration

A

Experiment used to find the concentration of a solution.

Involves gradually adding one solution to a known volume of another until the reaction between the 2 is complete.

86
Q

Volatility

A

Substance’s tendency to evaporate.

87
Q

Water of crystallisation

A

Water contained in an ionic lattice.

88
Q

Weak acid/base

A

An acid/base that only slightly ionises in an aqueous solution.

89
Q

Yield

A

Amount of product you get from a reaction.

90
Q

Hydrated salt

A

Salt that contains water of crystallisation.

GCSE OCR Chemistry (1 decks)

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