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Chemistry (own) > Definitions- define each term given > Flashcards

Definitions- define each term given Flashcards

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1
Q

Atomic number

A

The number of protons in the nucleus of an atom.

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2
Q

Mass number

A

The number of protons and neutrons in the nucleus of an atom.

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3
Q

Isotopes

A

Atoms of the same element so the same atomic number with different numbers of neutrons so different mass numbers.

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4
Q

Relative atomic mass, Ar

A

The ratio of the average mass of one atom of an element to one-twelfth of the mass of an atom of carbon-12.

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5
Q

Relative molecular mass, Mr

A

The ratio of the average mass of one molecule of a compound to one-twelfth of the mass of an atom of carbon-12.

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6
Q

Mole

A

The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope.

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7
Q

Avogadro’s constant, Na

A

The number of particles per mole (6.02 x 10^23).

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8
Q

Empirical formula

A

The simplest whole number ratio of atoms of each element present in a compound.

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9
Q

First ionisation energy

A

The energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.

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10
Q

Successive ionisation energy

A

The energy required to remove each electron in turn.

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11
Q

Electronegativity

A

The measure of the pull of an atom on a pair of electrons in a chemical bond.
OR
The ability of an atom to pull electron density towards itself within a covalent bond.

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12
Q

Ionic bond

A

A bond formed by the electrostatic forces of attraction between a positively charged ion and a negatively charged ion.

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13
Q

Covalent bond

A

Formed when atoms share a pair of electrons.

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14
Q

Metallic bonding

A

Bonding between atoms in a metal crystal. Each metal atom contributes electrons from its outer shell to a sea of delocalised electrons.

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15
Q

Dative covalent (coordinate) bond

A

A bond formed when one atom contributes both electrons in a covalent bond

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16
Q

Acid

A

A proton donor.

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17
Q

Anion

A

A negatively charged ion.

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18
Q

Period

A

A horizontal row of elements in the periodic table.

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19
Q

Salt

A

Compound formed when H+ from an acid is replaced by a metal ion or other positive ion.

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20
Q

Disproportionation

A

The oxidation and reduction of the same element in a redox reaction.

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21
Q

Thermal decomposition

A

The breaking up of a chemical substance with heat into at least two chemical substances.

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22
Q

Oxidation

A

The loss of electrons or increase in oxidation number.

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23
Q

Cation

A

A positively charged ion.

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24
Q

Molecular formula

A

The actual number of atoms of each element in a molecule.

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25
Q

Enthalpy change (🔼H)

A

The heat energy change in a reaction under constant pressure.

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26
Q

Standard conditions

A

100KPa (about 1 atm) pressure and a stated temperature, usually 298K.

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27
Q

Standard enthalpy of combustion

A

The enthalpy change of a compound when 1 mole of the compound is burned completely in oxygen under standard conditions, with all reactants and products in their standard state.

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28
Q

Standard enthalpy of formation

A

The enthalpy change when 1 mole of a compound is formed from its elements in their standard states under standard conditions.

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29
Q

Relative isotopic mass

A

The weight mean mass of an atom of an element compared with 1/12 of the mass of carbon 12

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30
Q

Relative formula mass

A

The formula mass is relative to the mass of an atom of carbon 12 which is defined as exactly 12.

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31
Q

Molar mass

A

The number of atoms, molecules, ions or other entities in one mole of a substance

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32
Q

Anhydrous

A

Anhydrous means ‘without water’

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33
Q

Hydrated

A

Contains water

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34
Q

Water of crystallisation

A

Water molecules which make up part of the crystal structure of a compound

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35
Q

Base

A

A proton acceptor

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36
Q

Alkali

A

A soluble base

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37
Q

Oxidation state

A

The state of oxidation or reduction shown by an element in its chemistry

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38
Q

Electron orbital

A

A subdivision of a sub shell. Each orbital contains upto 2 electrons

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39
Q

Electron shell

A

An energy level representing the distance of a group of electrons from the nucleus of an atom.

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40
Q

Permanent dipole

A

An intermolecular force between two polar molecules

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41
Q

Polar covalent bond

A

When two atoms with different electronegativities bond covalently

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42
Q

Intermolecular force

A

Attractive forces between molecules

43
Q

Hydrogen bond

A

A type of attraction between molecules which is much stronger than all the types of intermolecular forces but much weaker than covalent bonding

44
Q

Periodicity

A

A repeating pattern of properties shown across different periods

45
Q

Element

A

All the atoms of an element have the same number of protons in the nucleus.

46
Q

Reduction

A

A gain of electrons

47
Q

Reducing agent

A

Something that donates electrons

48
Q

Polymerisation

A

The joining together of monomers to form long chains.

49
Q

Electrophile

A

Electron pair acceptor

50
Q

Addition

A

Reaction which increases number of substituents

51
Q

Dehydration

A

The elimination of water from a compound

52
Q

Structural isomers

A

Compounds with the same molecular formula but different structural formulae

53
Q

Positional isomers

A

Compounds with the same molecular formula but different structures due to different positions of the same functional group on the same carbon skeleton

54
Q

Biofuel

A

A fuel made from plants or organic matter

55
Q

Oxidation state

A

The charge on the ion or element or atom

56
Q

Oxidising agent

A

A substance which accepts electrons

57
Q

Dynamic equilibrium

A

Rate of the forward reaction equals rate of the backwards reaction and concentrations of reactants and products remain constant

58
Q

Compromise temperature

A

Balance between rate and yield

59
Q

Activation energy

A

Minimum energy to start a reaction

60
Q

Catalyst

A

Speeds up a reaction but is chemically unchanged at the end

61
Q

Mean bond enthalpy

A

Enthalpy to break a covalent bond varies between compounds so an average value is used

62
Q

Stereoisomers

A

Compounds with the same structural formula but a different arrangement of atoms in space

63
Q

Rate of reaction

A

The change in concentration per unit of time

64
Q

Nucleophile

A

An electron pair donor

65
Q

Carbon neutral

A

An activity which has no net carbon emissions to the atmosphere

66
Q

Hess’s Law

A

Enthalpy change is independent of the route taken

67
Q

Racemic mixture

A

Equal mixture of enantiomers

68
Q

Bronsted-Lowry Acid

A

A proton donor

69
Q

Weak acid

A

A species which partially dissociates in solution to give H+ ions

70
Q

Strong acid

A

A species which fully dissociates in solution to give H+ ions

71
Q

Bronsted-Lowry Base

A

A proton acceptor

72
Q

Strong base

A

A species which fully dissociates in solution to give OH- ions

73
Q

Weak base

A

A species which partially dissociates in solution to give OH- ions

74
Q

pH

A

The negative logarithm to the base 10 of the hydrogen ion concentration

75
Q

Kw

A

The product the concentrations of hydrogen and hydroxide ions a solution

76
Q

Buffer

A

A solution which can resist a large pH change on addition of small amounts of acid or alkali

77
Q

Chiral

A

An atom attached to four different groups (or a molecule containing an atom attached to four different groups)

78
Q

Enantiomers

A

Molecules which are non-superimposable mirror images of each other

79
Q

Optical Activity

A

The ability to rotate the plane of plane-polarised light

80
Q

Second ionisation enthalpy

A

Enthalpy change when one electron is removed from each of a mole of free unipositive ions of that element in the gaseous state

81
Q

Enthalpy of Atomisation of an element

A

Enthalpy change when one mole of free gaseous atoms is produced from that element in its standard state.

82
Q

Enthalpy of Atomisation of a Compound

A

Enthalpy change when one mole of a compound in its standard state is converted into free gaseous atoms

83
Q

First Electron Affinity

A

Enthalpy change when one electron is added to each of a mole of free gaseous atoms of that element

84
Q

Second electron affinity

A

Enthalpy change when one electron is added to each of a mole of free gaseous uninegative ions of that element.

85
Q

Bond Dissociation Enthalpy

A

Mean Enthalpy change when one mole of covalent bonds is broken homolytically, resulting in free gaseous atoms

86
Q

Lattice Enthalpy

A

Enthalpy change when one mole of an ionic compound is formed from its free gaseous ions

87
Q

Lattice dissociation Enthalpy

A

Enthalpy change when one mole of an ionic compound is completely dissociated into free gaseous ions.

88
Q

Enthalpy of Hydration

A

Enthalpy change when one mole of free gaseous ions is added to an excess of water.

89
Q

Enthalpy of solution

A

Enthalpy change when one mole of an ionic compound is completely dissolved in an excess of water

90
Q

Entropy

A

A measure of the amount of disorder in a substance

91
Q

Spontaneous Reaction

A

A reaction for which the free energy change is negative.

92
Q

Amphoteric

A

A substance which is able to react with acid and alkalis

93
Q

Oxidation number

A

The charge that would exist on an atom if all the bonding were completely ionic

94
Q

Standard electrode potential

A

The emf of a cell in which the left-hand electrode is the standard hydrogen electrode and the right-hand electrode is the standard electrode in question.

95
Q

Ligand

A

A species which can use its lone pair of electrons to form a co-ordinate bond with a metal ion.

96
Q

Co-ordination number

A

The total number of co-ordinate bonds formed between the metal ion and the ligands in a complex

97
Q

Complex

A

A species containing a metal ion attached to one or more ligands by means of coordinate bonds

98
Q

Bidentate ligand

A

A ligand which uses two lone pairs of electrons to from two coordinate bonds with a metal ion.

99
Q

Multidentate ligand

A

A ligand which uses more than two lone pairs of electrons to form more than two coordinate bonds with a metal ion

100
Q

Homogeneous Catalyst

A

A catalyst in the same physical state as the reactants.

101
Q

Heterogeneous Catalyst

A

A catalyst in a different physical state to the reactants.

102
Q

Lewis Acid

A

An electron pair acceptor

103
Q

Lewis base

A

An electron pair donor

Chemistry (own) (14 decks)

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