Atoms, Elements and Compounds

Atoms, Elements and Compounds

1. Atoms

   • Have a small central nucleus made up of protons and neutrons around the electrons.
   • The electrons are involved in chemical reactions
   • All substances are made up of atoms
   • About 100 different types
   • Form chemical bonds by loosing, gaining or sharing a small number of electrons
   • Represented by a chemical symbol
   • When 2 or more atoms join together a molecule is formed
   • Atoms in elements and compounds are held together by taking or sharing electrons

2. Elements

   • A substance which contains one type of atom
   • Can have very different properties
     • e.g silver, copper and gold are shiny solids
     • e.g oxygen, nitrogen and chlorine are gasses
   • Are listed in the periodic table

3. Compounds

   • Contain 2 or more elements bonded together
     • e.g hydrogen and oxygen = water