JC Science Chemistry raid revison

A mixture

is made up of two or more substances mingled together but not chemically combined.

Elements

are substances made up of only one type of atom.

Molecules

are made up of two atoms chemically combined.

Compounds

are made up of two or more elements chemically combined

Mixtures

contains two or more different substances mingled together but not chemically combined.

Atomic number

is the number of protons (or electrons) in an atom of an element.

Mass number

is the number of protons and neutrons in an atom of an element.

Isotopes

are atoms of the same element which have the same atomic number but different mass numbers.

An alloy

is a mixture of metals

Corrosion

is an undesirable process whereby a metal changes to its oxide or some other compound by combining with oxygen in air.

An ion

is an atom which has lost or gained electrons.

An ionic bond

is the electrical force of attraction between positive and negative ions.

A covalent bond

consists of a pair of electrons shared between two atoms.

A physical change

is a change in which no new substance is formed.

A chemical change

is a change in which at least one new substance is formed.

A fuel

is a substance that burns in oxygen to produce heat.

Catalysts

are substances which alter the rate of a chemical reaction but are not used up themselves.

Electrolysis

is the splitting up of a compound by passing electricity through it.

A solution

is a mixture of a solute and a solvent.

A saturated solution

is a solution that contains as much dissolved solute as possible at that given temperature.

Crystallisation

is the formation of crystals by the cooling of a saturated solution.

Fuels

are substances which burn in oxygen to produce heat energy.

Hydrocarbons

are compounds made up of hydrogen and carbon.