C4a

C4a

1. Describe the particles in an atom and their relative charges and masses

   • Protons and neutrons are in the centre of the atom they make up the nucleus.
   • Electrons circle them in shells

2. Describe how the elements are arranged in the periodic table

   • The chemical elements are arranged in order of increasing atomic number

3. History of the periodic table

   • Dalton
     • All matter is made of atoms
     • Atoms cannot be broken down into anything simpler
     • All the atoms of a particular element are identical to each other and different from the atoms of other elements
     • Atoms are rearranged in a chemical reaction
   • Thomson
     • Atom contained smaller pieces

4. Structure of isotopes

   • Have the same number of protons but different number on neutrons