Igcse Chemistry Keywords

Front 1

Acid

Back 1

A sour substance which can attack metal, clothing or skin. When dissolved in water, its solution has a pH value less than 7. Acids are proton (H+ ion_ donors

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Activation energy

Back 2

The minimum energy needed for a reaction to take place

Front 3

Alkali Metal

Back 3

Elements in the group 1 of the periodic table, e.g. lithium (Li), sodium (Na), potassium (K)

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Alkali

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Its solution has a pH value more than 7

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Alkane

Back 5

Saturated hydrocarbon with the general formula CnH2n+2, e.g. methane, ethane, or propane

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Alkene

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Unsaturated hydrocarbon which contains a carbon-carbon double bond. Its general formula is CnH2n, e.g. ethene C2H4

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Alloy

Back 7

A mixture of metals (and sometimes non-metals). For example, brass is a mixture of copper and zinc

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Aluminium

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Low density, corrosion-resistant material used in many alloys, including those used in the aircraft industry

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Amphoteric

Back 9

an oxide that displays both acidic and basic properties

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Anhydrous

Back 10

Describes a substance that does not contain water

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Anode

Back 11

The positive electrode in electrolysis

Front 12

Aqueous solution

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The mixture made by adding a soluble substance to water

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Atmosphere

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The relatively thin layer of gases that surround planet Earth

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Atom

Back 14

The smallest part of an element that can still be recognised as that element

Front 15

Atomic Number

Back 15

The number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number

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Base

Back 16

The oxide, hydroxide or carbonate of a metal that will react with an acid, forming a salt as one of the products. (If a base dissolves in water it is called an alkali). Bases are proton (H+ Ion) acceptors

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Biodegradable

Back 17

materials that can be broken down by microorganisms

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Biodiesel

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Fuel for cars made from plant oils

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Bioleaching

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Process of extraction of metals from ores using microorganisms

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Biofuel

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Fuel made from animal or plant oils

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Blast Furnace

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the huge reaction vessels used in industry to extract iron form its ore

Front 22

Bond dissociation energy

Back 22

the energy required to break a specific chemical bond

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Brine

Back 23

A solution of sodium chloride in water

Front 24

Burette

Back 24

A long glass tube with a tap at one and markings to show volumes of liquid; used to add precisely known volumes of liquids to a solution in a conical flask below it

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Carbon Monoxide

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A toxic gas whose is CO

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Carbon steel

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alloy of iron containing controlled, small amounts of carbon

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Cast iron

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The impure iron taken directly from a blast furnace

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Catalyst

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A substance that speeds up a chemical reaction but remains chemically unchanged itself at the end of the reaction

Front 29

Catalytic Converter

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Fitted to exhausts of vehicles to reduce pollutants released

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Cathode

Back 30

The negative electrode in electrolysis

Front 31

Cement

Back 31

A building material made by heating limestone and clay

Front 32

Chromatography

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The process whereby small amounts of dissolved substances are separated by running a solvent along a material such as absorbent paper

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Climate change

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the change in global weather patterns that could be caused by excess levels if greenhouse gases in the atmosphere

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Closed system

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A system in which no matter or energy enters orleaves

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Collision theory

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An explanation of chemical reactions in terms of reacting particles colliding with sufficient energy for a reaction to take place

Front 36

Compound

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A substance made when two or more elements are chemically bonded together. For example, water (H2O) is a compound made from Hydrogen and Oxygen.

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Copper-rich ore

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Rock that contains a high proportion of a copper compound

Front 38

Covalent Bond

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The bond between two atoms that share one or more pairs of electrons

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Covalent bonding

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The attraction between two atoms that share one or more pairs of electrons

Front 40

Cracking

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The reaction used in the oil industry to break down large hydrocarbons into smaller, more useful ones. This occurs when the hydrocarbon vapour is either passed over a hot catalyst or mixed with steam and heated to a high temperature

Front 41

Delocalised electron

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Bonding electron that is no longer associated with any one particular atom

Front 42

Desalination

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The removal of salts from water to make it suitable for drinking and other uses

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Diffusion

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The automatic mixing of liquids and gases as a results of the random motion of their particles

Front 44

Displacement reaction

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A reaction in which a more reactive element takes the place of a less reactive element in one of its compounds or solution.

Front 45

Distillation

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Separation of a liquid from a mixture by evaporation followed by condensation

Front 46

Dot and cross diagram

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A drawing to show only the arrangement of the outer shell electrons of the atoms or ions in a substance

Front 47

Double Bond

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A covalent bond made by the sharing of two pairs of electrons

Front 48

Electrolysis

Back 48

The breakdown of a substance containing ions by electricity

Front 49

Electrolyte

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A liquid, containing free-moving ions, which is broken down by electricity in the process of electrolysis

Front 50

Electron

Back 50

A tiny particle with a negative charge, Electrons orbit the nucleus in atoms or ions

Front 51

Electronic structure

Back 51

A set of numbers to show the arrangement of electrons in their shells (or energy levels), e.g. the electronic structure