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Flashcards in Key Definitions Deck (110):
1

Mass number

The number of protons added to the number of neutrons in the nucleus
The top number on the periodic table

2

Atomic number

Is the number of protons in the nucleus
The bottom number on periodic table

3

Relative isotopic mass

Mass of an atom of an isotope compared to 1/12th the mass of a 12C atom

4

Isotopes

1:
Atoms with the same atomic number but different mass numbers
2:
Atoms that have the same number of protons but different number of neutrons

5

Orbital

Is a region around the nucleus where there is a high probability of finding an electron, can hold 2 electrons with opposite spins

6

Hunds rule

Electrons occupy orbitals singly before pairing happens

7

Pauli exclusion principle

Electrons in the same orbital must have opposite spins

8

A group

Vertical column in periodic table. Electron configuration is the highest occupied shell is the same for all atoms in main group

9

First ionisation energy

Energy per mile needed to remove an electron from gaseous atoms
X(g) -> X 2+ (g) + e-

10

Second ionisation energy

Energy per mile needed to remove an electron from gaseous ions with a single positive charge

11

Shielding

Electron-electron repulsion. It exists between two electrons in the same orbital between electrons in different orbitals

12

Atomic radius

Distance from the centre of the nucleus to the boundary of the Electron cloud, shows periodicity

13

Ion

Charged particle formed when an atom or group of atoms have lost or gained one or more electrons

14

Ionic bonding

Strong electrostatic forces of attraction between oppositely charged ions

15

Giant ionic lattice

Solid ionic compounds comprises oppositely charged ions arranged in a highly ordered way

16

Isoelectronic ions

Have same electronic configuration and number of electrons

17

Covalent bond

Strong electrostatic attraction between two nucleus and the shared pair of electrons between them

18

Dative covalent bonding

Forms when an orbital white a line pair of electrons in one atom overlaps with vacant orbital in another atom

19

Bond length

Distance between the nucleus of two atoms that are covalently bonded together
Measured in nanometres nm

20

Bond strength

Given by the bond enthalpy for a particular covalent bond

21

Bond enthalpy

Enthalpy change when one mole of w bond in the gaseous state is broken

22

VSEPR theory

Valence shell electron pair repulsion, lets you predict shapes of molecules and ions

23

Electronegativity

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

24

Polar covalent bond

Covalent bond is polar is two bonded atoms have different electronegativities

25

London forces

Type of intermolecular forces, acts between molecules

26

Instantaneous dipole

Don’t need differences in electronegativity, can exist in non polar molecules

27

Induced dipoles

Caused when a molecule comes close to a molecule with a permanent dipole or an instantaneous dipole

28

Hydrogen bonding

Intermolecular force between hydrogen and F O N

29

Solvent

Substance in which another substance can dissolve, forming a solution

30

Solute

Substance that dissolved in the solvent.

31

Soluble

Absolute is soluble if it can dissolve in given solvent

32

Solution

Is the mixture formed between solute and its solvent

33

Hydration

Water molecules surround individual ions and form strong electrostatic attractions with them

34

Metallic bonding

Strong electrostatic force of attraction between metal ions and the delocalised electrons

35

Oxidation number

Represents the number of electrons lost of gained by an atom of that element in a compound or iron

36

Systematic names

When an element can have more than one oxidation state, eg copper 11 oxide, copper 1 oxide

37

Redox reaction

Involves both reduction and oxidation, deceived in terms of transfer of electrons or changes in oxidation number

38

Oxidation

Gain of oxygen
Loss of electrons
Increase in oxidation number

39

Reduction

Loss of oxygen
Gain of electrons
Decrease in oxidation number

40

Oxidising agents

Gain electrons, electron acceptors

41

Reducing agents

Lose electrons, they are electron donors

42

Ionic half equations

Shows oxidation from one side of equation and reduction from the other side

43

Spectator ions

Present in a reaction but do not take part in the reaction

44

Ionisation

An atom is ionised if an electron absorbs enough energy to leave it altogether

45

Disproportionation reaction

Element in a single species is simultaneously oxidised and reduces

46

Confirmatory tests

Done to be sure of the identity of the haloed ions

47

Mole

The amount of substance that contains the same number of particles as the number of carbon atoms in exactly 12g of 12C

48

Avogadro constant

6.02 x 10^23 mol -1

49

Relative atomic mass
Ar

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

50

Relative formula mass
Mr

Calculated by adding together all Ar values for all the atoms present in a unit of a substance

51

Molar mass

Is the mass per mole of a substance
Unit g mol -1

52

Molecular formulae

Substance shows the actual numbers of atoms of each element in its molecules

53

Empirical formulae

Is the simplest whole number ratio of the atoms of each element it contains

54

Structural formula

Shows each atom and its position
CH3CH2CH2CH3

55

Equation

Balanced when it have same number of atoms of each element in left and right side of equation

56

Avogadro law

Equal volumes of gases under the same conditions of temperature and pressure contain the same number of molecules

57

Molar volume

Vm
24.0 dm3 mol-1 at RTP

58

Concentration

Of solute in a solution can be measured in Mol dm-3 or in g dm-3

59

Titration

Method in which the volumes of two reacting solutions are measured so that the concentration of one of the solutions can be determined

60

Atom economy

A way to assess chemical reactions, particularly in industrial processes

Is measured of how many atoms of the reactants end up in the desired product

61

Percentage yield

Actual yield / theoretical yield x 100
A way to assess chemical reactions

62

Hydrocarbons

Compounds of hydrogen and carbon only.

63

Alkanes

Hydrocarbon, saturdated, general formula of CnH2n+2

64

Displayed formula

H-c-c-h etc

Shows each atom and the bonds it has with other atoms

65

Structural formula

CH4
Shows each carbon atom and the atoms bonded to it

66

Isomers

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

67

Structural isomers

Have same molecular formula but their atoms are arranged in a different order

68

Alkenes

Unsaturated hydrocarbons, with general formula of CnH2n

69

Skeleton formula

Lines to represent each carbon link

70

Position isomers

Structural isomers with same carbon chain but with different functional group

71

Chain isomers

Structural isomers in which carbon chains are different

72

Stereoisomers

Same molecular formula. Same structural formula, different arrangement of atoms

73

E-Z isomers

E isomer is the higher priority groups opposite sides to each other
Z isomer the higher priority groups are together

74

Cis-trans isomers

Trans is E, when on opposite sides
Sis is Z when on same side

75

Substituent groups

Atoms or groups attached to the carbon atoms in c double bond

76

Crude oil

Petroleum
Mixture of hydrocarbons that can be separated by fractional distillation. Each fraction produced contains hydrocarbons with similar boiling points and chain lengths

77

Fractional distillation

Relies on differences in boiling temperatures of the different hydrocarbons in crude oil

78

Fractions

Crude oil heated and vapours are led into fractionating column hot at bottom and cool at top

79

Cracking

Involves chemical reactions that happen at high temperatures using catalyst zeolites and they decompose larger alkanes to produce smaller alkenes and alkanes u

80

Combustion

Of alkanes is an example of an oxidation reaction, in which oxygen reacts with the hydrogen and carbon atoms in the alkane molecules

81

Complete combustion

Happens when there is sufficient oxygen to oxidise the alkanes fully

82

Incomplete combustion

Happens when there is insufficient oxygen to oxidise the alkanes fully

83

Alternative fuels

Include biodiesel and bioalcohols from renewable sources such as plants

84

Fuel

Is a substance that can release energy usefully through chemical reactions

85

Non renewable

Once they’ve been used up they cannot be replaced

86

Carbon neutral

Refers to activity that has no overall annual carbon emissions to the atmosphere

87

Renewable energy

Eg wind, wave, solar and tidal power

88

Biodiesel

Made of vegetable oils such as rapeseed, sunflower and soya

89

Bioalcohol

Most common -bioethanol. Alcohol derived from materials produced by living organisms

90

Alcohols

Function group -OH

91

Homologous series

Same functional group, same general formula, similar chemical properties

92

Halogenalkanes

Functional group is halogen atom.

93

Radical substitution reactions

Alkanes under go this with halogens to produce halogenalkanes

94

Heterolytic fission

One atom gains both bonding electrons and ions form

95

Homolytic fission

Each atom keeps a bonding electron and radicals form

96

Radical

Species with an unpaired electron

97

Unpaired electron

Represented as a dot, places next to the atom whose bond was broken to form the radical

98

Substitution reaction

One atom or group is replaced by another atom or group

99

Reaction mechanisms

Shows bonds broken or formed and the species (atom or ion or molecule or radical)

100

Sigma bonds

Form end on overlap between two s orbitals, two p orbitals or an s and a p orbital

101

Pi bonds

Sideways overlap between p orbitals once a sigma bond has formed

102

Electrophilic addition reactions

Alkanes undergo reactions with hydrogen halides to produce halogenslkanes

103

Electrophile

Species able to accept a pair of electrons, and are attracted to a region of negative charge

104

Unsymmetrical alkenes

Undergo electrophilic addition reactions in which two products form, a major product and a Minor product

105

Halogenation

Reaction in which a halogen is added to another substance

106

Hydrogenation

Reaction in which hydrogen is added to another substance
Nickel catalyst used in hydrogenation

107

Oxidising agent

Alkanes react with oxidising agent to produce alcohols containing two hydroxyl groups

108

Exothermic

Overall transfer of energy from the system to the surroundings
Negative
Reactants have more energy than products

109

Endothermic

Overall transfer of energy to system from surroundings
Positive
Goes up

110

Standard conditions

100Kpa , 298K 1 mol dm-1