1. Aims: Establish prior knowledge, describe an atom using key words, calculate numbers of sub-atomic particles.

2.  Draw a diagram of an atom.  Include labels for all the key structures.

3. NameChargeMass Proton+11 a.m.u. NeutronNo charge1 a.m.u. ElectronPractically none.

4.  Record this information..  Atomic/Proton Number (A R ) – number of protons (also number of electrons for a neutral atom)  Symbol  Mass Number (M R ) – number of neutrons and protons.

5.  The Atomic/Proton number is the number of protons in an atom.  A normal atom of an element is electrically neutral. It has the same number of electrons as it has protons. (What do we call a charged atom or molecule?)  The Mass number of the atom is the number of protons and neutrons added together. (Why not electrons?)

6.  We can work out how many sub-atomic particles Sodium contains but where do they go?  In the centre is a nucleus which contains the protons and the neutrons (so all the mass).  This is surrounded by electrons which are held in energy levels called shells. The first shell holds 2 electrons, the second can hold 8 and the third can hold 8 electrons before it is full.

8.  Using the same format draw atom diagrams for the following elements.

9.  Science Quest 9 Student Worksheet 6.3 “Top 10 Elements”