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Atoms

1. All substances are made from atoms

   • A substance made of only one sort of atom is call an element.
   • A substance made from two or more sort of atoms are called compounds

2. Atoms are represented by a chemical symbol, eg O represents the atom of Oxygen

3. Atoms have a small central nucleus which is made up of protons and neutrons and around which are electrons.

   • Proton has a +1 charge
   • Neutron has a 0 charge
   • Electron has a -1 charge
   • In an atom, the number of electrons is equal to the number of protons in the nucleus
   • Atoms have no overall charge

4. The number of protons is equal to the atomic number