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Description
Atoms, Elements and
Compounds
1 Atoms
1.1 Have a small central nucleus made up of protons and neutrons around the
electrons.
1.2 The electrons are involved in chemical
reactions
1.3 All substances are made up of atoms
1.4 About 100 different types
1.5 Form chemical bonds by loosing, gaining or sharing a small number of
electrons
1.6 Represented by a chemical symbol
1.7 When 2 or more atoms join together a molecule is formed
1.8 Atoms in elements and compounds are held together by taking or sharing electrons
2 Elements
2.1 A substance which contains one type of atom
2.2 Can have very different properties
2.2.1 e.g silver, copper and gold are shiny solids
2.2.2 e.g oxygen, nitrogen and chlorine are gasses
2.3 Are listed in the periodic table
3 Compounds
3.1 Contain 2 or more elements bonded together
3.1.1 e.g hydrogen and oxygen = water