1.1. A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes

________ is a compound containing 1 atom of hydrogen and 1 of chlorine per molecule ● Compounds can only be separated into elements by chemical reactions Mixtures ● A mixture consists of two or more elements or compounds not chemically combined together.

HCl

________ always involve the formation of one or more new substances, and often involve an energy change ● Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of the atoms from which they were formed e.g.

Chemical reactions

________ represents an atom of sodium ● Compounds are formed from elements by chemical reactions.

Na

filtration, crystallisation, simple distillation, fractional distillation and chromatography

(this is different to a compound) ● Can be separated by