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Nat5 Revision > Chemistry > Flashcards

Chemistry Flashcards

1
Q

what does a chemical reaction always result in?

A

an energy change.

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2
Q

what is usually produced by an energy change in a chemical reaction?

A

heat, light or sound energy.

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3
Q

what do u need to measure the energy changes in most chemical reactions?

A

the temperature of the reactant and product.

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4
Q

what occurs in an endothermic reaction?

A

the products contain more energy than the reactants.

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5
Q

what occurs in an exothermic reaction?

A

the reactants contain more energy than the products.

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6
Q

chemical reactions can be followed by measuring changes in what?

A

Volume of gas produced, mass, concentration, pH.

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7
Q

how do you calculate the average rate of reaction?

A

average rate = change in quantity/ time taken.

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8
Q

what are protons, neutrons and electrons known as?

A

sub-atomic particles.

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9
Q

what is the mass of an electron?

A

1/2000.

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10
Q

what is the mass number of an element equal to?

A

the number of protons plus the number of neutrons.

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11
Q

what is the RAM of an element?

A

the average mass of the isotopes of the element.

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12
Q

elements with the same number of outer electrons have what in common?

A

there in the same group and have similar chemical properties.

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13
Q

how many electrons does the first energy level hold up to?

A

2.

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14
Q

how many electrons does the second energy level hold up to?

A

8.

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15
Q

how many electrons does the third energy level hold up to?

A

8.

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16
Q

what is an ion?

A

an atom that has become electrically charged.

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17
Q

how do you work out the number of protons from chemical notation of an ion?

A

it equals the atomic number.

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18
Q

how do you work out the number of electrons from chemical notation of an ion?

A

look at the charge of the ion, if it is negatively charged the ion has gained electrons, if it is positively charged the ion has lost electrons.

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19
Q

how do you work out the number of neutrons from chemical notation of an ion?

A

the mass number minus the atomic number.

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20
Q

what is a covalent bond?

A

a shared pair of electrons between 2 atoms (usually non-metals).

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21
Q

what holds the two atoms together in a covalent bond?

A

the force of attraction between the positive nuclei and the bonded (or shared) electrons.

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22
Q

what is a molecule?

A

a group of atoms joined by covalent bonds.

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23
Q

what is a diatomic molecule?

A

a molecule that contains only two atoms joined by a covalent bond.

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24
Q

compounds that are solid at 20 degrees celcius can be what?

A

ionic or covalent.

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25
Q

Give a reason for covalent compounds being liquids or gases at 20 degrees celcius.

A

they contain many millions of atoms joined by very strong covalent bonds in a network, or, they are made from small, discrete molecules held together by weak forces of attraction between the molecules.

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26
Q

compounds that are liquids or gases at 20 degrees celcius are what?

A

covalent only.

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27
Q

some covalent substances are insoluble in water but soluble in what other kind of solvents?

A

non-aqueous solvents.

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28
Q

what is the prefix for 1 atom?

A

mono…

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29
Q

what is the prefix for 2 atom?

A

di…

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30
Q

what is the prefix for 3 atom?

A

tri…

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31
Q

what is the prefix for 4 atom?

A

tetra…

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32
Q

what is the prefix for 5 atom?

A

penta…

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33
Q

what is the prefix for 6 atom?

A

hexa…

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34
Q

what method do you use to write chemical formulae?

A

symbol, valancy, swap.

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35
Q

what is the valency number of an element?

A

the number of electrons available to form bonds.

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36
Q

name the seven diatomic elements.

A

hydrgen, oxygen, nitrogen, fluorine, chlorine, bromine, iodine.

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37
Q

why do atoms form bonds?

A

to achieve a stable electron arrangement, full outer shell.

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38
Q

what is a bond?

A

a force of attraction between ions or atoms.

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39
Q

what holds ions and atoms together?

A

bonds.

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40
Q

how are elements arranged in the periodic table?

A

by increasing atomic number.

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41
Q

what are isotopes?

A

atoms of the same element with different mass numbers.

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42
Q

how are electrons arranged outside the nucleus?

A

in different energy levels, known as the electron arrangement.

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43
Q

what are elements made up of?

A

very small particles called atoms.

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44
Q

where are protons and neutrons found?

A

in the nucleus of an atom.

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45
Q

where are electrons found?

A

moving in the space around the nuleus of an atom.

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46
Q

what charge does a proton have?

A

positively charged.

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47
Q

what charge does a neutron have?

A

nuetral - have no charge.

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48
Q

what charge does a electron have?

A

negatively charged.

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49
Q

why are atoms neutral?

A

they have equal numbers of protons and neutrons.

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50
Q

what is the law of conservation of mass?

A

the total mass of the reactants must equal the total mass of products in a chemical reaction.

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51
Q

what happens to the temperature in an endothermic reaction?

A

it falls.

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52
Q

what happens to the temperature in an exothermic reaction?

A

it rises.

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53
Q

what are the variables that can affect the rate of a chemical reaction?

A

particle size, concentration, temperature and adding a catalyst.

54
Q

what happens to the rate of a reaction when the particle size is decreased?

A

it increases.

55
Q

what happens to the rate of a reaction when the concentraion is increased?

A

it increases.

56
Q

what happens to the rate of a reaction when the temperature is decreased?

A

it decreases.

57
Q

what happens to the rate of a reaction when a catalyst is added?

A

it increases.

58
Q

what is a catalyst?

A

a substance that can be used to speed up a chemical reaction but are not used up during the reaction and can be recovered chemically unchanged.

59
Q

what is an enzyme?

A

a biological catalyst.

60
Q

give 2 examples of an exothermic reaction.

A

combustion and neutalisation reactions.

61
Q

all substances (reactants and products) contain what?

A

chemical potential energy.

62
Q

how are positively charged ions formed?

A

when metal ions loose electrons.

63
Q

how are negatively charged ions formed?

A

when non-metal atoms gain electrons.

64
Q

what is an ionic bond?

A

the strong force of attraction between positive metal ions and negative non-metal ions.

65
Q

ionic compounds exist as what?

A

lattices of positive and negative ions.

66
Q

why are ionic compounds solids at 20 degrees celcius?

A

because there are very strong forces of attraction between oppositely charged ions.

67
Q

what happens to an ionic lattice dissolves in water?

A

it breaks up completely.

68
Q

do ionic compounds conduct electricity when solid? and why?

A

no. because the ions are not free to move.

69
Q

ionic compounds conduct electricity when in what 2 states?

A

in an aqueous solution or molten.

70
Q

what is electrolysis?

A

the movement of electricity through an ionic compound that separates it in to elements.

71
Q

why can electrolysis only take place in ionic compounds?

A

because they contain ions.

72
Q

what happens when electricity passes through an ionic compound in solution.

A

elements are formed at each electrode.

73
Q

what is an electrolyte?

A

an ionic compound dissolved in water or molten that conducts electricity.

74
Q

what kind of current must be used during electrolysis? and why?

A

d.c. because it allows the products to form and be identified.

75
Q

what happens to the positively charged metal ions during electrolysis?

A

they accept electrons from the negative electrode and become neutral atoms.

76
Q

what happens to the negatively charged non-metal ions during electrolysis?

A

they donate electrons to the positive electrode and become neutral molecules.

77
Q

why are some ionic compounds coloured?

A

because some metal ions are coloured.

78
Q

what can experiments using coloured ions be used for?

A

to show that ions are charged particles.

79
Q

what three elements react with oxygen to produce (element)dioxide?

A

sulfur, nitrogen and carbon. all non- metal oxides.

80
Q

carbon dioxide, sulfur dioxide and nitrogen dioxide dissolve in water to produce what? and what does this do?

A

acids. increases the hydrogen ion (H+).

81
Q

state two ways carbon dioxide can be produced.

A

naturally by respiration and by burning fossil fuels.

82
Q

state two ways nitrogen dioxide can be produced.

A

naturally during lightening storms and by the sparking of air on a car engine.

83
Q

how is sulfur dioxide produced?

A

by burning fossil fuels, especially coal.

84
Q

give 3 effects of acid rain.

A

leaves on trees are damaged and fall off, corrosion of metals is increased, aluminium ions washed into lakes kill fish.

85
Q

how is acid rain produced?

A

when sulfur and nitrogen dioxide dissolve with water in the atmosphere.

86
Q

name 3 common household acids.

A

vinegar, lemon juice, fizzy drinks

87
Q

name 3 common household alkalis.

A

soap, bleach, toothpaste

88
Q

what do acidic and alkaline solutions contain?

A

ions.

89
Q

what is the pH of a solution?

A

a measure of the concentration of hydrogen ions (H+).

90
Q

what can water molecules do?

A

dissociate into hydrogen and hydroxide ions.

91
Q

what is the test for hydrogen?

A

it burns with a pop.

92
Q

what kind of ions do all acidic solutions contain?

A

(H+(aq)).

93
Q

what kind of ions do all alkaline solutions contain?

A

(OH-(aq)).

94
Q

metal oxides and metal hydroxides dissolve in water to make what and what does that change?

A

alkaline solutions. increases the concentraion of hydroxide ions.

95
Q

what happens when you dilute an acid with water?

A

makes it less acidic, decreases the concentration of H+ ions, increases its pH towards 7 and decreases its electrical conductivity.

96
Q

what happens when you dilute an alkali with water?

A

makes it less alkaline, decreases the concentration of OH- ions, decreases its pH towards 7 and decreases its electrical conductivity.

97
Q

how do you calculate the formula mass of a compound?

A

by adding together the relative atomic masses of the elements present in the formula.

98
Q

what is gram formula mass?

A

the formula mass of a substance expressed in grams

99
Q

what is gram formula mass also known as?

A

relative formula mass.

100
Q

what is the gfm equal to?

A

one mole of a substance.

101
Q

what is the equation relating: gram formula mass, mass and number of moles?

A

m = n x gfm

102
Q

what is the equation relating: volume, mass and concentration?

A

n = v x c

103
Q

what is the concentration of a solution?

A

a measure of how much of a substance is dissolved in 1 litre of water.

104
Q

give four examples of neutralisers or bases.

A

metal oxides, metal hydroxides, metal carbonates and MAZITL metals.

105
Q

what is a base?

A

a substance which neutralises an acid.

106
Q

what does a reaction between an acid and a base always produce?

A

a salt.

107
Q

metal oxide + acid =?

A

a salt + water.

108
Q

metal hydroxide + acid =?

A

a salt + water.

109
Q

metal carbonate + acid =?

A

a salt + water + carbondioxide.

110
Q

MAZITL metal + acid =?

A

a salt + hydrogen.

111
Q

what are spectator ions?

A

ions that do not take part in a chemical reaction.

112
Q

what happens in a precipitation reaction?

A

2 solutions react to form a precipitate (an insoluble solid).

113
Q

give 2 examples of everyday neutralisation reactions.

A

reducing the acidity of soil by adding lime, reducing the effects of acid rain on lakes by adding lime or treating acid indigestion.

114
Q

what happens when acid rain reacts with metal structures?

A

it causes them to corrode.

115
Q

what is a fuel?

A

a chemical which burns to produce energy.

116
Q

what happens to the boiling point as the size of the molecules increase?

A

it increases.

117
Q

what happens to the flammability as the size of the molecules increase?

A

it decreases.

118
Q

what happens to the viscosity as the size of the molecules increase?

A

it increases.

119
Q

in car engines what does the energy from the spark of the spark club cause?

A

the nitrogen and oxygen from the air to combine to make nitrogen oxides.

120
Q

what are biofuels?

A

liquid or gaseous fuels made form plant or animal material.

121
Q

what is a homologous series?

A

a chemical family with the same general formula and similar chemical properties.

122
Q

what is cracking?

A

an industrial process for producing smaller more useful molecules using larger unwanted molecules.

123
Q

what are isomers?

A

molecules with the same molecular formula but different structural formula.

124
Q

give 2 properties of the alkanes.

A

insoluble in water and very flammable.

125
Q

give 2 properties of the alkenes.

A

insoluble in water and very flammable.

126
Q

give 2 properties of the cycloalkanes.

A

insoluble in water and very flammable.

127
Q

give 2 properties of the alcohols.

A

some are soluble in water and all are very flammable.

128
Q

give 3 properties of the carboxylic acids.

A

soluble in water, very flammable and pH<7.

129
Q

give an example of a rechargeable battery.

A

a car battery.

130
Q

how is a simple cell made?

A

by connecting 2 different metals together and placing them in an electrolyte.

131
Q

give an example of an electrolyte.

A

sodium chloride, NaCl(aq).

132
Q

why does the metal higher in the ecs loose electrons in a displacement reaction?

A

to form ions and the metal ions in the solution gain these ions to become atoms.

Nat5 Revision (4 decks)

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