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Chemistry IG > Definitions and formulas > Flashcards

Definitions and formulas Flashcards

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1
Q

Melting point definition

A

Temperature when a substance begins to change from solid to liquid

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2
Q

Boiling point definition

A

Temperature when a substance begins to change from liquid to gas

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3
Q

Pressure definition

A

The force exerted by gas molecules colliding with surfaces of objects or other particles

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4
Q

Temperature definition

A

The average kinetic energy of the particles in a substance

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5
Q

Diffusion definition

A

Diffusion is the net movement of particles from an area of high concentration to an area of low concentration until they’ve reached equilibrium.

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6
Q

Concentration definition

A

Concentration is a measure of how much of a substance there is in a single area, in other words, the amount of substance per unit volume.

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7
Q

Element definition

A

Pure substances made up of only one type of atom

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8
Q

Compound definition

A

Pure substances that are formed when two or more elements chemically combine

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9
Q

Mixture definition

A

A combination of two or more substances (elements and/or compounds) that arenotchemically combined

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10
Q

Molecule definition

A

Two elements bonded together

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11
Q

Proton number/atomic number definition

A

the number of protons in the nucleus of an atom

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12
Q

Mass number/nucleon number definition

A

the total number of protons and neutrons in the nucleus of an atom

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13
Q

Isotope definition

A

different atoms of the same element that have the same number of protons but different numbers of neutrons

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14
Q

Calculating atomic mass using isotopes formula

A

Atomic mass= (fractional abundance of isotope 1 x mass number of isotope 1) + (fractional abundance of isotope 2 x mass number of isotope 2)

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15
Q

Ionic bond definition

A

An ionic bond is a strong electrostatic attraction between oppositely charged ions

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16
Q

Ion definition

A

An ion is an electrically chargedatom or group of atoms formed by the lossor gain ofelectrons

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17
Q

Covalent bond definition

A

A covalent bond is formed when a pair of electrons is shared between two atoms leading to noble gas electronic configurations

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18
Q

Simple molecular substance meaning

A

A simple molecular substance is a covalent substance that is made up of a small number of non-metal atoms held together with a small number of covalent bonds

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19
Q

Giant covalent structure meaning

A

A giant covalent structure is networks made up of a large number of non-metal atoms, held together with a large number of strong covalent bonds

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20
Q

Allotrope meaning

A

An allotrope is two or more physical forms in which an element can exist. E.g. diamond and graphite are both made of carbon

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21
Q

Metallic bonding definition

A

the electrostatic
attraction between the positive ions in a giant metallic lattice and a ‘sea’ of delocalised electrons

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22
Q

Molecular formula definition

A

The number and type of different atoms in one molecule

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23
Q

Empirical formula definition

A

The simplest whole number ratio of the different atoms or ions in a compound

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24
Q

Relative atomic mass (Ar) definition

A

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

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25
Q

Relative molecular mass (Mr) definition

A

The sum of the relative atomic masses. Relative formula mass is used for ionic compounds

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26
Q

Mole definition

A

A mole (unit: mol) is the unit of amount of substance and one mole contains 6.02 × 10^23 particles, e.g. atoms, ions, molecules; this number is the Avogadro constant

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27
Q

Avogadro’s constant

A

Number of atoms in a mole (6.02x10^23)

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28
Q

Conversion cm^3 to dm^3

A

1000cm^3 = 1dm^3

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29
Q

Conversion between mol/dm^3 and g/dm^3

A

To convert between mol/dm^3 and g/dm^3 multiply by molar mass in grams

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30
Q

Electrolysis definition

A

decomposition of an
ionic compound, when molten or in aqueous
solution, by the passage of an electric current

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31
Q

Percentage yield definition and formula

A

Percentage yield is the ratio of actual yield obtained compared to the expected or theoretical yield
Actual yield/theoretical yield

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32
Q

Percentage composition by mass formula

A

total mass of element in compound/relative formula mass of compound

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33
Q

Percentage purity formula

A

Mass of pure substance/total mass of substance

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34
Q

Exothermic reaction definition

A

an exothermic reaction transfers thermal energy to the surroundings leading to an increase in the temperature of the surroundings

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35
Q

Endothermic reaction definition

A

an endothermic reaction takes in thermal energy from the surroundings leading to a decrease in the temperature of the
surroundings

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36
Q

What are the axes for reaction pathway diagrams?

A

x-axis: progress of reaction
y-axis: energy

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37
Q

What is enthalpy change?

A

the transfer of thermal energy during a
reaction is called the enthalpy change, ∆H, of the reaction

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38
Q

Unit of enthalpy

A

kJ/mol

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39
Q

Activation energy definition (Ea)

A

The minimum energy that colliding particles must have to react

40
Q

What type of process is bond breaking and bond making?

A
  • Bond breakingis always anendothermicprocess as energy needs to be taken in from the surroundings to break the chemical bonds
  • Bond makingis always anexothermicprocess as energy is transferred to the surroundings as the new bond is formed
41
Q

Enthalpy calculation formula

A

(ΔH) = Energy taken in (bonds broken, reactants) - Energy given out (bonds made, products)

42
Q

Catalyst definition

A

Substance that increases the rate of a reaction and is unchanged at the end of a reaction. It decreases the activation energy of a reaction

43
Q

Hydrated definition

A

(substance) chemically combined with water

44
Q

Thymolphthalein colour in base and acid

A

Base: blue
Acid: Colourless

45
Q

Water of crystallisation definition

A

water molecules present in hydrated crystals

46
Q

Redox reaction definition

A

reactions where oxidation and reduction take place together simultaneously.

47
Q

What is an oxidising agent?

A

An oxidising agent is a substance that oxidises another substance and is itself reduced

48
Q

What is a reducing agent?

A

A reducing agent is a substance that reduces another substance and is itself oxidised

49
Q

ANY ELEMENT OXIDATION NUMBER IS 0

A
50
Q

Strong acid definition

A

an acid that is completely
dissociated in aqueous solution

51
Q

Weak acid definition

A

an acid that is partially dissociated in aqueous
solution (use reversible reaction sign)

52
Q

Amphoteric oxide definition

A

oxides that react
with acids and with bases to produce a salt and
water (Al2O3 and ZnO)

53
Q

Solubility rules for salts

A

(a) sodium, potassium and ammonium salts are soluble
(b) nitrates are soluble
(c) chlorides are soluble, except lead and silver
(d) sulfates are soluble, except barium, calcium and lead
(e) carbonates are insoluble, except sodium,
potassium and ammonium
f) hydroxides are insoluble, except sodium,
potassium, ammonium and calcium (partially)

54
Q

Anhydrous definition

A

substance containing
no water

55
Q

Periodic table definition

A

an arrangement of
elements in periods and groups and in order of
increasing proton number/ atomic number

56
Q

Trends down group 1

A

relatively soft metals
(a) decreasing melting point
(b) increasing density
(c) increasing reactivity
- They react readily with oxygen and water vapour in air so they are stored underoilto stop them from reacting
- Group I metals will react similarly with water, reacting vigorously to produce analkalinemetal hydroxide solution andhydrogengas

57
Q

Trends down group VII

A

diatomic non-metals
(a) increasing density
(b) decreasing reactivity

58
Q

Appearance of halogens at rtp

A

(a) chlorine, a pale yellow-green gas
(b) bromine, a red-brown liquid
(c) iodine, a grey-black solid

59
Q

Transition metals characteristics

A

(a) have high densities
(b) have high melting points
(c) form coloured compounds
(d) often act as catalysts as elements and in
compounds
having ions with
variable oxidation numbers, including iron(II) and iron(III)

60
Q

Alloy definition

A

alloy is a mixture of a metal with other elements

61
Q

Sacrifical protection definition

A

a method of corrosion prevention where a more reactive metal is used to protect a less reactive one.

62
Q

Galvanising definition

A

a process where the iron to be protected is coated with a layer of zinc. This can be done by electroplating or dipping it into molten zinc

63
Q

Functional group definition

A

an atom or group
of atoms that determine the chemical properties
of a homologous series

64
Q

Structural formula definition

A

a structural formula is an
unambiguous description of the way the atoms
in a molecule are arranged

65
Q

Structural isomer definition

A

structural isomers as compounds with the
same molecular formula, but different structural
formulae

66
Q

Homologous series definition

A

A family of similar compounds with similar chemical properties due to the presence of the same
functional group

67
Q

Saturated compound definition

A

a saturated compound has molecules in which all carbon–carbon bonds are single bonds

68
Q

Unsaturated compound definition

A

an unsaturated compound has molecules in which one or more carbon–carbon bonds are not single bonds

69
Q

General characteristics of homologous series

A

(a) having the same functional group
(b) having the same general formula
(c) differing from one member to the next by
a –CH2– unit
(d) displaying a trend in physical properties
(e) sharing similar chemical properties

70
Q

How to extract metals high in reactivity series?

A

Electrolysis

71
Q

How to extract metals middle in reactivity series?

A

These metals are typically extracted by heating with reducing agent such as carbon or carbon monoxide

72
Q

How to extract metals low in reactivity series

A

Metals lower in the reactivity series are found in nature in their pure form or in less reactive compounds (copper may have to be extracted from its ore by heating with carbon or hydrogen). Called native ores.

73
Q

Hydrocarbon definition

A

compounds containing only hydrogen and carbon atoms

74
Q

Petroleum definition

A

mixture of hydrocarbons

75
Q

Uses of the fractions

A

Refinery gas
- gas used in heating and cooking

Gasoline/petrol fraction
- fuel used in cars

Naphtha fraction
- a chemical feedstock (raw materials used in the mass production of chemical products)

Kerosene/paraffin fraction
- jet fuel

Diesel oil/ gas oil fraction
- fuel used in diesel engines

Fuel oil fraction
- fuel used in ships and home heating systems

Lubricating oil fraction
- lubricants, waxes and polishes

Bitumen fraction
- making roads

76
Q

Substitution reaction definition

A

one atom or group of atoms is replaced by another atom or group of atoms

77
Q

What is photochemical reaction

A
  • Alkanes undergo a substitution reaction with chlorine in the presence of ultraviolet light (normally sunlight)
  • The ultraviolet light provides the activation energy (Ea)
78
Q

Addition reaction definition

A

In an addition reaction, only one product is formed

79
Q

How to produce ethanol- fermentation of glucose

A

fermentation of aqueous glucose at 25–35°C
in the presence of yeast and in the absence of
oxygen

80
Q

How to produce ethanol- steam to ethene

A

catalytic addition of steam to ethene at 300°C and 6000kPa /60 atm in the
presence of an acid catalyst

81
Q

Advantages of fermentation

A

Simple equipment
Uses renewable resources
Low temp and pressure (lower cost)
Less energy needed

82
Q

Disadvantages of fermentation

A

Slow reaction
Batch process (takes lots of stop and start)
Produces a dilute solution that needs further processing
Carbon dioxide produced which is greenhouse gas

83
Q

Advantages of addition of steam to ethene

A

Fast reaction
Continuous process
Creates pure ethanol
No greenhouse gases produced but pollutants are formed from the burning of fossil fuels to maintain high temperatures

84
Q

Disadvantages of addition of steam to ethene

A

High temperature and pressure (cost increase)
Non-renewable raw materials (petroleum)
Lots of energy needed (more workers)
Complex equipment

85
Q

Polymer definition

A

large molecules built up from many smaller molecules called monomers

86
Q

Addition polymerisation definition

A

Formed from many unsaturated monomers bonding together to form a long chain polymer with no byproducts

87
Q

Condensation polymerisation definition

A

Condensation polymers are formed whentwodifferent monomers with two functional groupsare linked together with theremovalof a small molecule, usuallywater

88
Q

Solvent definition

A

solvent as a substance that dissolves a solute

89
Q

Solute definition

A

substance that is dissolved in a solvent

90
Q

Solution definition

A

mixture of one or more solutes dissolved in a solvent

91
Q

Saturated solution definition

A

a solution containing the maximum concentration of a solute dissolved in the solvent at a specified temperature

92
Q

Filtrate definition

A

A liquid or solution that has passed through a filter

93
Q

Residue definition

A

Substance that remains after evaporation, filtration, distillation or any other similar process

94
Q

Chromatography definition

A

Chromatography is a technique used to separate mixtures of soluble solid materials so they can be identified

95
Q

Paper chromatography

A

Paper chromatography is used to separate mixtures of soluble coloured substances, using a suitable solvent

96
Q

Rf formula

A

Rf = distance travelled by substance/distance travelled by solvent

Chemistry IG (14 decks)

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