Edexcel Gcse Science Chemistry C1 Revision

Front 1

The early atmosphere
1. What produced the gases that formed the atmosphere?
2. What were the two main gasses in the early atmosphere?
3. How did the oceans form?
4. Where does our evidence about the early atmosphere come from?

Back 1

1. Volcanoes
2. Carbon dioxide and water vapour
3. As the Earth cooled down, water vapour in the atmosphere condensed to form liquid water.
4. We can look at modern volcanoes, and at the atmospheres of other planets like Mars and Venus (because they also have volcanoes).

Front 2

Acid rain

Back 2

Rain that is more acidic than normal, due to sulfur dioxide and nitrogen oxides dissolved in it.

Front 3

Alkali

Back 3

A soluble base

Front 4

Alkane

Back 4

A hydrocarbon with only single bonds between two carbon atoms.

Front 5

Alkene

Back 5

A hydrocarbon with at least one double bond between carbon atoms.

Front 6

Alloy

Back 6

A mixture of more than one metals.

OR

A mixture containing at least one metal and carbon.

Front 7

Alloy steel

Back 7

An alloy of iron with other metals.

Front 8

Antacid

Back 8

A compound that is used to neutralise acid in the stomach.

Front 9

Aqueous solution [higher]

Back 9

Mixture formed when a substance dissolves in water.

Front 10

Atmosphere

Back 10

Layer of gases that surrounds the Earth.

Front 11

Atom

Back 11

The smallest part of an element that can take part in chemical reactions.

Front 12

Balanced equation [higher]

Back 12

Description of a reaction using the symbols and formulae of the reactants and products.

Front 13

Base

Back 13

A substance that will react with an acid to form only salt and water.

Common bases:

Metal oxides, e.g. Copper oxide

Metal hydroxides, e.g. potassium hydroxide

Metal carbonates, e.g. calcium carbonate

Front 14

Biodiesel

Back 14

Diesel fuel made from plant material.

Front 15

Biofuel

Back 15

Any fuel made by humans from animal or plant materials that have recently died.

These are different to fossil fuels, which take millions of years to form.

Front 16

Biogas

Back 16

Methane made from animal manure or biodegradable waste from homes and farms.

Front 17

Bitumen

Back 17

The fraction of crude oil with the longest molecules. It is used for making roads and roofs.

Front 18

Boiling point

Back 18

The temperature at which all of a substance starts to turn into a gas (evaporate).

This can also be described as the condensing point - where the gas will turn back into a liquid.

Front 19

Bonds

Back 19

Forces of attraction holding atoms together in a molecule.

Front 20

Bromine test

Back 20

A test for unsaturation. Bromine water turns from reddish-brown to colourless when mixed with an unsaturated molecule.

This happens because the double bonds (in an alkene) will open up to bond with the bromine atoms.

Front 21

Bromine water

Back 21

A solution of bromine in water that turns colourless when mixed with an unsaturated molecule.

It changes from reddish-brown to colourless because the double bond will open up to bond with bromine atoms.

Front 22

Carats [higher]

Back 22

A measure of the purity of gold alloys.

Pure gold is 24 carats (it contains no other metals and is a pure metal rather than an alloy).

50% gold would be 12 carats.

Front 23

Carbon cycle

Back 23

A sequence of processes by which carbon moves from the atmosphere, through living and dead organisms, into sediments and into the atmosphere again.

Front 24

Carbon neutral

Back 24

A fuel or process that does not add any carbon dioxide to the atmosphere overall.

Front 25

Cement

Back 25

Material made by heating limestone with clay.

Front 26

Chalk

Back 26

Sedimentary rock, mostly calcium carbonate, made from the remains of marine micro-organisms.

Front 27

Chemical formula

Back 27

A combination of symbols and numbers that shows how many atoms of different kinds are in a particular molecule. In compounds that do not form molecules, it shows the ratio of elements in the compound.

Front 28

Chemical potential energy

Back 28

The energy stored in matter, which can be released by a chemical reaction (such as combustion).

Front 29

Climate change

Back 29

Changes to the Earth's climate, or changes in weather patterns on a global scale.

Front 30

Combustion

Back 30

Chemical reaction when substances burn, combining with oxygen to produce heat and waste products such as carbon dioxide.

Front 31

Complete combustion

Back 31

Combustion of hydrocarbons with enough oxygen present to convert all the fuel into carbon dioxide and water.

Front 32

Compound

Back 32

A substance containing two or more elements chemically joined together.

Front 33

Concentration

Back 33

The amount of a substance dissolved in a certain quantity of liquid.

E.g.

g/cm3, mg/100 cm3).

Front 34

Concrete

Back 34

Material made by mixing cement with sand, stones and water.

Front 35

Control

Back 35

An experiment that uses the same apparatus as the main part of the experiment but the variable that is being changed is not applied.

The point is to give you a comparison with the real experiment, to check that the independent variable really is causing a change in the dependent variable.

Front 36

Convection current

Back 36

A current caused by parts of a fluid being at a different temperature and so a different density to the rest of the fluid.

Front 37

Convention

Back 37

A standard way of doing something.

Front 38

Core

Back 38

The middle of the Earth.

This is mainly iron, very hot and solid. Despite the fact that its temperature is ~5700 K, it is solid because the pressure is so high - this keeps it compressed into a solid.

Front 39

Corrosion

Back 39

Occurs when a metal is converted to its oxide by the action of moist air.

Front 40

Cracking

Back 40

Splitting up long hydrocarbon molecules into shorter ones.

Front 41

Criterion

Back 41

Rule or test that can be used to judge how to make a fair decision (plural: criteria).

Front 42

Crude oil

Back 42

A mixture of hydrocarbons formed from dead microscopic organisms by heat and pressure over millions of years.

Front 43

Crust

Back 43

The outer surface of the Earth.

Front 44

Crystal

Back 44

A solid in which the particles are arranged in an ordered pattern.

Front 45

Deforestation

Back 45

The destruction of the world's trees and forests.

This can contribute to global warming because destroying trees means there are less to remove carbon dioxide and produce oxygen; this leads to an overall increase in the amount of carbon dioxide in the atmosphere.

Front 46

Denitrifying bacteria [higher]

Back 46

Bacteria that break down more complex nitrogen compounds into simpler ones, such as nitrates to nitrites, or nitrites to ammonia.

Front 47

Dense

Back 47

Something that has a lot of mass in a given volume.

Front 48

Density

Back 48

The mass of a substance per unit volume; the unit is usually g/cm3.

Front 49

Diesel oil

Back 49

Fraction of crude oil used as a fuel in lorries and some cars.

Front 50

Double bond

Back 50

When two bonds join a pair of the same atoms (usually two carbon atoms).

Front 51

Ductile

Back 51

Can be stretched into wires.

E.g.

Copper metal is ductile - this property means that it can be pulled (drawn) into thin wires.

Front 52

Earthquake

Back 52

A sudden movement within the Earth, releasing a large amount of stored energy.

Front 53

Electrode

Back 53

Part of an electrical circuit that makes contact with a sample.

Front 54

Electrolysis

Back 54

Passing a direct electrical current through an electrolyte to decompose it.

E.g.

Hydrochloric acid (the electrolyte) can be decomposed by electrolysis to produce hydrogen and chlorine gasses.

Front 55

Electrolyte

Back 55

A liquid which conducts the electric current and is decomposed by it.

Front 56

Element

Back 56

Substance that cannot be split up into simpler substances.

Front 57

Epicentre

Back 57

The point on the surface of the Earth directly above the focus of an earthquake.

Front 58

Erosion

Back 58

Removal or transportation of broken up rocks.

Front 59

Ethanol

Back 59

An alcohol, made by processing sugar beet or sugar cane.

Front 60

Extraction (metal)

Back 60

Reaction in which a metal is produced from a compound in an ore.

Unreactive metals are found as pure metals, so do not need extracting.

Slightly reactive metals can be extracted by heating with carbon.

Ver reactive metals have to be extracted using electrolysis.

Front 61

Fineness [higher]

Back 61

A measure of the purity of gold in parts per thousand with pure gold having a fineness of 1000.

Front 62

Focus

Back 62

The place where an earthquake begins, usually under the surface.

Front 63

Formula (chemical)

Back 63

The composition of a substance showing the symbols of the elements it contains, and the ratios in which their atoms are present.

Front 64

Fossil

Back 64

The remains or trace evidence of prehistoric living organisms.

Front 65

Fossil fuel

Back 65

Non-renewable fuels such as coal, oil and natural gas that have formed over millions of years from dead plants and animals.

Front 66

Fractional distillation

Back 66

The process by which a mixture of two or more liquids is separated, for example crude oil is separated into different fractions.

Front 67

Fractions

Back 67

The different mixtures into which crude oil is separated.

Front 68

Fuel cell

Back 68

A device which produces electricity from hydrogen and oxygen without burning.

Front 69

Fuel oil

Back 69

Crude oil fraction used as fuel for ships and for lubrication.

Front 70

Global warming

Back 70

The increase in the Earth's average temperature likely to be caused by increased amounts of carbon dioxide in the atmosphere.

Front 71

Granite

Back 71

Igneous rock with relatively large crystals, formed when magma cools and solidifies slowly.

Front 72

Greenhouse effect

Back 72

When gases in the atmosphere trap heat energy and keep the Earth warm.

Front 73

Greenhouse gases

Back 73

Gases that help to trap heat in the atmosphere. They include carbon dioxide, methane and water vapour.

Front 74

Hazard symbol

Back 74

A symbol used on containers that warns people about the dangers of the contents.

Front 75

Hazardous

Back 75

Something that could be harmful or dangerous if not used and stored properly.

Front 76

Hyrdocarbon

Back 76

A compound containing only hydrogen and carbon atoms.

Front 77

Igneous rock

Back 77

Rock formed when magma cools and solidifies.

Front 78

Ignite

Back 78

To start burning

Front 79

Incomplete combustion

Back 79

Combustion that occurs without enough oxygen to completely oxidise all the fuel. Incomplete combustion of hydrocarbons produces carbon dioxide, carbon monoxide and carbon (soot).

Front 80

Insoluble

Back 80

Substance which does not dissolve in a given solvent.

Front 81

Ion

Back 81

An atom that has become electrically charged. Atoms become ions when they gain or lose electrons.

Front 82

Iron seeding

Back 82

Adding iron compounds to the oceans to encourage organisms to grow and remove carbon from the carbon cycle.

Front 83

Kerosene

Back 83

Crude oil fraction used as a fuel for jet engines.

Front 84

Lava

Back 84

Molten rock on the Earth's surface.

Front 85

Limestone

Back 85

Sedimentary rock, mostly calcium carbonate, made from the remains of marine organisms.

Front 86

Limewater

Back 86

A solution of calcium hydroxide that turns milky when carbon dioxide is bubbled through it.

Front 87

LItmus paper

Back 87

Blue litmus paper turns red in acid solutions.

Red litmus paper turns blue in alkaline solutions.

Front 88

Magma

Back 88

Molten rock inside the Earth's crust.

Front 89

Malleable

Back 89

Can be hammered into shape.

Front 90

Mantle

Back 90

The part of the Earth between the crust and the core.

Front 91

Marble

Back 91

Metamorphic rock, mostly calcium carbonate, formed from limestone or chalk.

Front 92

MIxture

Back 92

A substance containing two or more different substances that are not joined together.

Front 93

Model

Back 93

An example of something happening, which explains how a scientific idea should be understood.

Front 94

Molecule

Back 94

Two or more atoms joined together.

Front 95

Monomer

Back 95

Small molecule used to make a polymer.

Front 96

Neutralisation reaction

Back 96

Reaction in which a base of alkali reacts with an acid.

Front 97

Nitinol

Back 97

An alloy of nickel and titanium, which is a shape memory alloy.

Front 98

Nitrifying bacteria

Back 98

Bacteria that make more complex nitrogen compounds from simpler ones, such as nitrates from nitrites, or nitrites from ammonia.

Front 99

Nitrogen cycle

Back 99

A sequence of processes by which nitrogen moves from the atmosphere through living and dead organisms, into the soil and back to the atmosphere.

Front 100

Nitrogen-fixing bacteria

Back 100

Bacteria that can take nitrogen from the atmosphere and convert it to more complex nitrogen compounds, such as ammonia.

Front 101

Noble gases

Back 101

Unreactive gases in Group 0 of the periodic table.

Front 102

Non-renewable

Back 102

Any energy resource that will run out one day.

Front 103

Non-renewable resources

Back 103

Resources that cannot be replaced once they have been used. Non-renewable resources will eventually run out.

E.g.

Fossil fuels - coal, oil and natural gas.

Front 104

Nucleus

Back 104

The central part of an atom, containing protons and neutrons.

Front 105

Ore

Back 105

Rock from which a metal can be extracted for profit.

Front 106

Oxidation

Back 106

Occurs when oxygen is added to an element or compound.

Front 107

Permeable

Back 107

A solid that allows a liquid or a gas to pass through it is described as being permeable.

Front 108

Petrol

Back 108

Crude oil fraction used as fuel for cars.

Front 109

pH scale

Back 109

A scale from 1 to 14 showing acidity or alkalinity. Numbers below 7 are acids. Numbers above 7 are alkalis. pH 7 is neutral.

Front 110

Photosynthesis

Back 110

Set of chemical reactions in plants that allow them to produce their own food (glucose) using water and carbon dioxide and releasing oxygen as a waste product. The process is powered by light from the Sun.

Front 111

Plastic

Back 111

The common name for many polymers.

Front 112

Pollutant

Back 112

A substance that harms living organisms when released into the environment, often waste products of human activity.

Front 113

Poly(chloroethene)

Back 113

A polymer made from ethene monomers.

Front 114

Poly(ethene)

Back 114

A polymer made from ethene monomers.

Front 115

Poly(propene)

Back 115

A polymer made from propene monomers.

Front 116

Poly(tetrafluoroethene)

Back 116

The chemical name for PTFE, which is also known as Teflon.

Front 117

Polymer

Back 117

A long molecule made by joining many smaller molecules (monomers) together.

Front 118

Polymerisation

Back 118

The process of making a polymer.

Front 119

Population growth

Back 119

Increase in population size over time.

Front 120

Precipitate

Back 120

Insoluble product formed in a precipitation reaction.

Front 121

Precipitation reaction

Back 121

Reaction in which an insoluble product is formed from soluble reactants.

Front 122

Primary data

Back 122

Data that you collect yourself.

Front 123

Product

Back 123

Substance formed by a chemical reaction.

Front 124

PVC

Back 124

Another name for poly(chloroethene).

Front 125

Quarry

Back 125

Shallow mine on the Earth's surface from where rocks are removed.

Front 126

Rate

Back 126

How quickly something happens.

Front 127

Reactant

Back 127

Substance used up in a chemical reaction.

Front 128

Reactivity series

Back 128

A list of metals arranged in order of reactivity.

Front 129

Recycle

Back 129

To extract a material from waste so that it can be reused or processed to make a new object or material.

Front 130

Recycling

Back 130

Taking materials from waste and making them into useful products again.

Front 131

Reduction

Back 131

Occurs when oxygen is removed from a compound.

Front 132

Renewable

Back 132

Any energy resource that will not run out.

Front 133

Renewable energy resources

Back 133

Resources that will not run out, such as solar or wind energy.

Front 134

Rusting

Back 134

The corrosion of iron.

Front 135

Salt

Back 135

A compound formed by neutralisation of an acid by a base. The first part of the name comes from the metal in the metal oxide, hydroxide or carbonate. The second part of the name comes from the acid.

Front 136

Saturated

Back 136

A molecule with only single bonds between the carbon atoms.

Front 137

Secondary data

Back 137

Data that you use from someone else's report, book, TV programme etc..

Front 138

Sediment

Back 138

Process by which solid material that settles to the bottom of a fluid, such as water.

Front 139

Sedimentary rock

Back 139

Rock made by compression of layers of solid material (sediment) that settles to the bottom of a fluid, such as water.

Sedimentary rocks normally form at the bottom of the ocean.

Front 140

Shape memory alloy [higher]

Back 140

An alloy that returns to its original shape with a change in conditions, often temperature.

Front 141

Smart material

Back 141

A material with a property that changes with a change in conditions.

Front 142

Solidify

Back 142

To become solid.

Front 143

Soluble

Back 143

Substance which will dissolve in a given solvent.

Front 144

Soot

Back 144

Tiny particles of solid carbon produced by incomplete combustion.

Front 145

Stable

Back 145

Something that stays the same, without changing.

Front 146

State symbol [higher]

Back 146

Letter or letters to show the state of a substance.

Front 147

Tar

Back 147

Sticky black substance in tobacco smoke that contains carcinogens.

Front 148

Thermal decomposition

Back 148

Reaction in which one substance breaks down when heated to form two or more new substances.

Front 149

Thermal energy

Back 149

Energy transferred by heating.

Front 150

Trace

Back 150

A tiny amount of something.

Front 151

Transfer

Back 151

To move something.

Front 152

Universal indicator

Back 152

A mixture of different indicators giving a different colour at different points on the pH scale.

Front 153

Unsaturated

Back 153

A molecule with at least one double bond between carbon atoms.

Front 154

Viscosity

Back 154

How thick or runny a liquid is. Low viscosity is very runny, high viscosity is thick.

Front 155

Word equation

Back 155

Description of a reaction using the names of the reactants and products.

Front 156

The Earth's first atmosphere was formed by gases produced from volcanoes.

We think these gases were mainly carbon dioxide and water vapour.

Back 156

The Earth was very hot to start with, and there were no oceans. As the earth cooled down the water vapour in the atmosphere condensed to form liquid water. This liquid water became the oceans.

Explain why scientists cannot be certain about the composition of the early atmosphere? There were no humans around to measure the atmosphere, so they have to use clues. There are different sources of information, but not all the evidence leads to the same conclusion. This means that it is difficult to know exactly what the early atmosphere was like and how it has changed.

Front 157

The early atmosphere

1. What produced the gases that formed the atmosphere?

2. What were the two main gasses in the early atmosphere?

3. How did the oceans form?

4. Where does our evidence about the early atmosphere come from

Back 157

1. Volcanoes

2. Carbon dioxide and water vapour

3. As the Earth cooled down, water vapour in the atmosphere condensed to form liquid water.

4. We can look at modern volcanoes, and at the atmospheres of other planets like Mars and Venus (because they also have volcanoes).

Front 158

The amounts of different gases in the atmosphere are shown in the pie chart and table. The atmosphere also contains water vapour, but this is not usually included because the amount changes depending on the weather.

Back 158

The composition of the atmosphere today is not constant. It can be changed by human activities. Burning fossil fuels releases carbon dioxide into the atmosphere. Sulphur dioxide can also be released from burning coal.