atomic structure and the periodic table

atomic structure and the periodic table

1. atoms are made up of three subatomic particles called protons,neutrons and electrons.

   • protons mass is 1 and its charge is +1
     • remember the charge on a proton is positive, the charge on a neutron is neutral and the charge on a electron is negative.
   • neutrons mass is 1 and its charge is 0
   • electrons mass is negligible and its charge is -1
   • the protons and neutrons are in nucleus (centre) of the atom and the electrons orbit round the outside in shells (or orbits).

2. the atomic number is the number of protons that the atoms has. it is also the number of elctrons that a neutral atom has.

3. the mass number is the number of protonds and neutreons added together.

4. Rule: to calculate the number of neutrons = mass number - atomic number

5. the electrons are arranged in shells(or orbits) the number of electrons that you can fit into each energy level is as follows

   • In the first shell you can fit 2 electrons
     • In the second shell you can fit 8 electrons
       • in the third shell you can fit 8 electrons

6. different elemants will have different atomic numbers ,no two elemants will have the same number of protons.

   • an isoptope is an elemant which has the same number of protons and electrons but has different number of neutrons