C1 exam: Key words to understand
There are lots of new key terms that you need to make sure you understand in preparation for your exam. It’s really
important that you recognise what each of the words mean and are able to use them correctly in a sentence. This
will help you to explain ideas scientifically and ensure you pick up important marks in your exam.
Some tips for learning science vocabulary.
Tip 1 -Play some games with the keywords
You could play hangman with your friends or family using the words you need to learn. Make sure you explain what
the word means when they have guessed it.
You could play Pictionary for some of the energy types or renewable energy sources. Ask someone to draw you a
picture for one of these terms and see if you can guess which one they are drawing.
Tip 2 – Use flash cards
Write out the key word and the definition on separate cards, mix them up and see if you can match the keyword
with the correct description.
Write the keyword on one side and the definition on the other. Look at the keyword side and see if you can
remember the definition or read the definition and try to remember the keyword. Turn the card over to check, or
ask someone else to read them out to you.
See if you can sort the keywords into groups of similar words. For example, you could group together all the words
that give a different type of energy. Try to explain why you have grouped them together to a friend or family
member.
Tip 3 – Spelling strategies
Use the spelling strategies that you talk about in tutor time to help with any words that you find difficult to spell.
Break it into sounds
Break it into syllables
Break it into word parts
Use a mnemonic
Refer to word in the same family
Say it as it sounds
Words within words
Make connections between words
Think about the meaning of words
Apply spelling rules
Learn by sight
(d-i-a-r-y)
(re-mem-ber, con-tin-ent)
(dis+satisfy)
(necessary—one collar, two sleeves, rhythm has your
two hips moving)
(muscle—muscular)
(Wed-nes-day)
(Parliament—I AM parliament, GUM in argument)
(bright, light, night, etc)
(bi+cycle = two+wheels)
(writing, written)
(look—cover—write—check)
Topic 1 – The Earth’s sea and atmosphere
Key term
What it means
Atmosphere
Layers of gases that surround the earth
Deforestation
The destruction of the world’s trees and forests
Limestone
Sedimentary rock, mostly calcium carbonate made from the
remains of marine organisms
Noble gases
Unreactive gases in Group 0 of the periodic table
Photosynthesis
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. This process is powered by
light from the Sun.
Sedimentary rock
Rock made by compression of layers of solid material (sediment
that settles to the bottom of a fluid, such as water)
Trace
A small amount of
Topic 2 – Materials from the Earth
Key term
What it means
Aqueous solution
Mixture forms when a substance dissolves in water.
Atom
The smallest part of an element that can take part in chemical
reactions
Balanced equation
Description of a reaction using the symbols and formulae of the
reactants and products, so that the number of ‘units’ of each
element to the left of the arrow is the same as those to the right
of the arrow
Cement
Material made by heating limestone with clay
Chalk
Sedimentary rock, mostly calcium carbonate, made from the
remains of marine micro-organisms
Compound
A substance containing two or more elements chemically joined
together
Concrete
Material made by mixing cement with sand, stones and water
Crystal
A solid in which the particles are arranged in an ordered pattern
Key term
What it means
Element
Substance that cannot be split up into simpler substances
Erosion
Removal or transportation of broken up rocks
Fossil
The preserved traces or remains of an organism that lived a very
long time ago
Granite
Igneous rock with relatively large crystals, formed when magma
cools and solidifies slowly
Igneous rock
Rock formed when magma cools and solidifies
Insoluble
Substance which does not dissolve in a given solution
Lava
Molten rock on the Earth’s surface
Limewater
A solution of calcium hydroxide that turns milky when carbon
dioxide is bubbled through it
Magma
Molten rock inside the Earth’s crust
Marble
Metamorphic rock, mostly calcium carbonate, formed from
limestone or chalk
Metamorphic rock
Rock formed the action of very hot temperature and pressure on
other rocks
Neutralisation reaction
Reaction in which a base or alkali reacts with an acid
Quarry
Shallow mine on the Earth’s surface from where rocks are
removed
Precipitate
Insoluble solid formed when two solutions are mixed together and
a precipitation reaction occurs
Precipitation reaction
A reaction in which an insoluble product is formed from soluble
reactants
Product
Substance formed by a chemical reaction
Rate
How quickly something happens
Reactant
Substance used up in a chemical reaction
Solidifies
To become solid
Soluble
Substance which dissolves in a given substance
Key term
What it means
State symbols
Letter or letters to show the state of a substance e.g. (g) for gas)
Thermal decomposition
Reaction in which one substance breaks down when heated to
form two or more new substances
Word equation
Description of a reaction using the names of the reactants and
products
Topic 3 - Acids
Key term
What it means
Acid
A substance with a pH of less than 7. The stronger the acid, the
lower the pH number
Alkali
Bases that dissolve in water are called alkalis. They are solutions
with excess OH- ions and have a pH greater than 7
Alkali metal
An element in group 1 of the periodic table
Anode
Positive electrode
Anion
A negative ion, produced by gaining electrons (usually a non-metal
ion)
Antacid
A compound that is used to neutralise acid in the stomach
Aqueous solution
A mixture formed when a substance dissolves in water
Balanced equation
Bases
Description of a reaction using the symbols and formulae of the
reactants and products, so that the number of ‘units’ on each side
of the reaction is the same
Substances that can react with acids and neutralise them to make
a salt and water are called bases. They are usually metal oxides or
metal hydroxides
Boiling point
This is the maximum temperature a liquid can achieve. For water,
the boiling point is 100oC (at standard atmospheric pressure)
Bonds
Two elements joined in a chemical bond (types are ionic, covalent
and metallic)
Cathode
A negative electrode
Cation
A positively charged ion, produced by losing electrons (usually a
metal ion)
Chemical formula
A combination of symbols and numbers that show 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 a compound
Key term
What it means
Compound
A substance containing more than one type of atom chemically
joined together
Concentration
A measure of how much solute is dissolved in a solvent. Units are
g dm3 or mol dm3
Conductor (electrical)
A sample that allows electricity to pass through it
Conservation of mass
A law that states that no mass is gained or lost in a chemical
reaction
Corrosion
Chemical changes to metals converting them to compounds, as in
rusting of iron
Corrosive
A material that wears away and destroys
Current
A movement of electrons (or other charged particles)
Electricity
A flow of charged particles that can be used to transfer energy
Electrode
A rod made of carbon of conducting metal which carries the
current in an electrolyte
Electrolysis
The process in which an electrical current decomposes a
compound
Electrolytes
Ionic liquid where moving ions carry an electrical current during
the process of electrolysis
Electron
A particle with negligible mass and a charge of -1
Electroplating
The process where a metal is coated with a thin coating of another
metal using electrolysis
Element
One type of atom
Hazard symbols
Symbols used on containers to warn users of its contents
Hazardous
A substance that could be dangerous if not used or stored
properly
Indicator
A substance which can change colour depending on the pH of a
solution
Indigestion
Pain caused by excess acid in the stomach
Insoluble
A substance which does not dissolve in a given solvent
Ion
An atom with an electrical charge
Key term
What it means
Litmus paper
Blue litmus paper turns red in acidic solutions and red litmus
paper turns blue in alkaline solutions
Mixture
A substance containing two or more substances that are not
chemically joined together
Molecule
Two or more atoms joined together with a covalent bond
Neutralisation reaction
Reaction between an acid and a base to form a salt and water
Neutron
Particle found in the nucleus, with no charge and a mass of 1
pH scale
A scale from 1-14 showing acidity or alkalinity
Proton
Particle found in the nucleus, having a mass of 1 and a charge of
+1
Salt
Salts are made when an acid reacts with a base, carbonate or
metal. The name of the salt formed depends on the metal in the
base and the acid used. For example, salts made using
hydrochloric acid are called chlorides
Universal indicator
A mixture of dyes that changes colour gradually over a range of pH
and is used in testing for acids and alkalis
Topic 4 – Obtaining and using metals
Key term
What it means
Alloy
A mixture of different metals
Alloy steel
Iron that is alloyed with a variety of elements in total amounts
between 1.0% and 50% by weight to improve its mechanical
properties
Atoms
The smallest particle of a chemical element
Bonds
Two elements joined in a chemical bond (types are ionic, covalent
and metallic)
Carats
A measure of the purity of gold with pure gold being 24 carat
Chemical formula
A combination of symbols and numbers that show 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 a compound
Compound
A substance containing more than one type of atom chemically
joined together
Key term
What it means
Conduct
Allows something to pass through (heat or electricity)
Conductor (electrical)
A sample that allows electricity to pass through it
Density
The mass of substance per unit volume (unit is usually g/cm3)
Ductile
Can be stretched into wires
Electricity
A flow of charged particles that can be used to transfer energy
Electrolysis
The process in which an electrical current decomposes a
compound
Electroplating
The process where a metal is coated with a thin coating of another
metal using electrolysis
Element
One type of atom
Extraction
Reaction in which a metal is produced from a compound in an ore
Malleable
Can be hammered into shape
Melting point
The point at which a substance turns from a solid to a liquid
Mixture
A substance containing two or more substances that are not
chemically joined together
Ores
Rock from which a metal can be extracted for profit
Oxidation
A reaction in which oxygen is added to a chemical; loss of an
electron by a negative ion
Reactivity
How fast or how readily an element reacts
Reactivity series
A list of metals arranged in order of reactivity
Recycle
To extract a metal from waste to be reused or processed to make
a new object or material
Reduction
Occurs when oxygen is removed from a compound. Gain of an
electron by a positive ion
Rusting
The corrosion of iron
Shape memory alloy
An alloy that returns to its original shape with a change in
conditions, often temperature
Topic 5 - Fuels
Key term
What it means
Acid rain
Rain that is more acidic than normal, has a pH lower than 5.2
Alkane
A hydrocarbon in which all the bonds between the carbon atoms
are single bonds
Alkene
A hydrocarbon in which there are one or more double bonds
between carbon atoms
Biodegradable
A substance that can be broken down by microorganisms
Biodiesel
Diesel fuel made from plant material
Biofuel
A fuel made from plants or microorganisms
Boiling point
Temperature at which a substance changes from a liquid to a gas
Bonds
The way in which atoms in molecules are joined
Bromine test
A test for unsaturation. Bromine water turns colourless when
mixed with an unsaturated molecule.
Bromine water
A solution of bromine in water that turns colourless when mixed
with an unsaturated molecule
Carbon monoxide
Carbon neutral
A toxic gas (CO), it is made during incomplete combustion. It
replaces oxygen in the blood and so reduces the amount of
oxygen carried around the body
Whereby the carbon dioxide added to the atmosphere when the
fuel is burnt is only
replacing that which was removed from the atmosphere, during
photosynthesis, when the plant was growing. Therefore overall
no more carbon dioxide is being added to the atmosphere
Climate change
The idea that the Earth’s climate is changing. Many scientists
believe this is linked to increasing carbon dioxide levels
Combustion
Chemical reaction when substances burn, combining with oxygen
to produce heat and waste products such as carbon dioxide
Complete combustion
Combustion of hydrocarbons with enough oxygen present to
convert all the fuel into carbon dioxide and water
Cracking
A type of chemical reaction in which large alkane molecules are
decomposed into two or more smaller molecules to form smaller
alkanes and alkenes
Crude oil
A mixture of hydrocarbons formed from dead microscopic
organisms by heat and pressure over millions of years
Double bond
When two bonds join a pair of the same atoms (usually two
carbon atoms)
Ethanol
A fuel made by processing sugar beet or sugar cane
Fossil fuel
Non-renewable fuels such as coal, oil and natural gas that have
formed over millions of years from dead plants and animals
Fractional distillation
A method of separating a mixture of liquids with different boiling
points into individual components (fractions)
Fraction
A component of a mixture that has been separated by fractional
distillation
Fuel cell
A device which produces electricity from hydrogen and oxygen
without burning
Hydrocarbon molecules
A compound of hydrogen and carbon only
Ignite
To start burning
Incinerated
Burnt, i.e. waste
Incomplete combustion
Combustion that occurs without enough oxygen to completely
oxidise all the fuel. Incomplete combustion of hydrocarbons
produces carbon dioxide, carbon monoxide and carbon (soot)
Limewater
A solution of calcium hydroxide that turns milky when carbon
dioxide is bubbled through it
Mixture
A substance containing two or more different substances that are
not joined together
Monomer
Small molecule used to make a polymer
Non-renewable resource
Resources that cannot be replaced once they have been used.
These will eventually run out
Plastics
The common name for many polymers
Poly(chloroethene)
A polymer made from chloroethene monomers. Also known as
PVC
Poly(ethene)
A polymer made from ethane monomers
Poly(propene)
A polymer made from propene monomers
Poly(tetrafluoroethene)
The chemical name for PTFE, which is also known as Teflon
Polymer
A long molecule made by joining many smaller molecules
(monomers) together
Polymerisation
The process of making a polymer
Key term
Renewable
Saturated
What it means
Something that can be made without diminishing the resources
used to make it, such as biofuels made from plants that can be
grown again
A molecule which contains only single bonds between the carbon
atoms and has the maximum possible number of atoms attached
to the carbon chain
Soot
Tiny particles of solid carbon produced by incomplete combustion
Unsaturated
A molecule which contains one or more double bonds between
the carbon atoms, allowing extra atoms to be added on to the
carbon chain
Viscosity
How thick or runny a liquid is. Low viscosity is very runny, high
viscosity is thick