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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
Shielding
Lessening of the pull of the outer electron caused by the electrons between the nucleus and the outer electron.
26
Charge density
Amount of charge in relation to the size of an ion.
27
Disproportionation
A single element is simultaneously oxidised and reduced.
28
Enthalpy change
Heat energy transferred in a reaction at constant pressure.
29
Standard enthalpy change of reaction
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.
30
Standard enthalpy change of formation
Enthalpy change when 1 mole of a compound is formed from its elemetns in their standard states under standard conditions.
31
Standard enthalpy change of combustion
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.
32
Standard enthalpy change of neutralisation
Enthalpy change when solutions of an acid and an alkali react together to form 1 mole of water, under standard conditions.
33
Hess' Law
Total enthalpy change of a reaction is always the same, no matter which route is taken.
34
Catalyst
A substance that increases the rate of reaction by providing an alternative reaction pathway with lower activation energy.
35
Activation energy
The minimum amount of KE that particles need for a successful collision.
36
Reaction rate
How fast a reaction takes place.
37
Structural formula
Minimum detail that shows the arrangement of the atoms in a molecule.
38
Displayed formula
Shows the relative positioning of atoms and the bonds between them.
39
Homologous series
Series of organic compounds having the same functional group with successive members differing by CH2.
40
Functional group
Group of atoms responsible for the characteristic reactions of a compound.
41
Structural isomers
Same molecular formula; different bonding patterns of atoms.
42
Chain isomers
Isomers caused by different arrangements of the C-atoms to form straight or branched chains.
43
Positional isomers
Isomers caused by different POSITIONS of the SAME functional groups.
44
Functional group isomers
Isomers caused by different functional groups.
45
Stereoisomers
Isomers resulting from different spatial arrangements of some atoms with the same structural formula.
46
Optical isomers
4 different groups bonded to a central (chiral) C atom such that one isomer is the non-identical mirror image of each other.
47
Geometrical isomers
A different arrangement of the SAME group about a C=C group.
48
Acids
Proton donors which release H+ ions when mixed with water (in aqueous solution).
49
Alkalis
Bases that are soluble in water and release OH- ions in aqueous solution.
50
Anhydrous salt
Salt that doesn't contain any water of crystallisation.
51
Base
A substance that removes H+ ions from an aqueous solution (proton acceptor).
52
Complete combustion
Burning a substance completely in an excess of O2. Burning a hydrocarbon produces CO2 + H2O only.
53
Concentration
A measure of how many moles (or grams) of a substance are dissolved in a volume of solution.
54
Dehydration reaction
Reaction in which water is eliminated from an organic molecule.
55
Distillation
A technique used to separate liquids with different b.p.
56
Giant covalent lattice / macromolecular structure
A structure consisting of a huge network of covalently bonded atoms.
57
Giant ionic lattice structure
A repeated structure made up of oppositely charged ions strongly attracted to each other in all directions.
58
Giant metallic lattice structure
A regular structure consisting of closely packed metal cations in a sea of delocalised electrons.
59
Greenhouse effect
Absorption and re-emission of IR radiation by greenhouse gases in the atmosphere.
60
Greenhouse gas
Gas that absorbs and emits IR radiation and contributes to the greenhouse effect.
61
Incomplete combustion
Burning a substance in poor supply of oxygen. Burning a hydrocarbon produces CO + H2O. And sometimes C and CO2.
62
Ionisation
Removal of one or more electrons from an atom or molecule, resulting in an ion forming.
63
Isotope
1 of 2 or more forms of an element with the same number of protons but different numbers of neutrons and masses.
64
Isotopic abundance
Relative amount of a particular isotope occurring in a sample of an element.
65
Mass spectrometry
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
Mass spectrum
Chart produced by a mass spectrometer.
67
Haloalkane
Alkane with at least 1 halogen atom in place of a H2 atom.
68
Nomenclature
Naming organic compounds.
69
Oxidation number
The total number of electrons an element has donated or accepted.
70
Percentage yield
Amount of product that is actually obtained during a reaction.
71
Periodicity
Trends in physical and chemical properties of elements as you go across the periodic table.
72
Pi bond
Type of bond formed when 2 p orbitals overlap sideways.
73
Polar bond
A covalent bond where a difference in electronegativity has caused a shift in electron density in the bond.
74
Radical
A particle with an unpaired electron.
74
Percentage yield
Amount of product that is actually obtianed during a reaction.
75
Oxidising agent
A chemical that accepts electrons and gets reduced.
76
Reducing agent
A chemical that donates electrons and gets oxidised.
77
Saturated hydrocarbon
Hydrocarbon where all the carbon-carbon bonds are single bonds.
78
Simple molecular structure
A compound with strong covalent bonds within its molecules but weak London forces between its molecules.
79
Spin
Momentum possessed by an electron.
80
Standard conditions
101 kPa / 1 atm. 25 °C / 298 K.
81
Successive ionisation energy
The energy needed to remove 1 mole of each subsequent electron from each ion in 1 mole of positively charged gaseous ions.
82
Theoretical yield
Mass of product that should be formed in a chemical reaction if no reactant or product is 'lost'.
83
Unsaturated hydrocarbon
A hydrocarbon with 1 or more carbon-carbon double bonds, carbon-carbon triple bonds or an aromatic group.
84
Titration
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
Titration
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
Volatility
Substance's tendency to evaporate.
87
Water of crystallisation
Water contained in an ionic lattice.
88
Weak acid/base
An acid/base that only slightly ionises in an aqueous solution.
89
Yield
Amount of product you get from a reaction.
90
Hydrated salt
Salt that contains water of crystallisation.

GCSE OCR Chemistry (1 decks)

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