Link back to previous topic - this holding power does not always behave in the same way - we have seen sometimes very organised and sometimes disorganisaed. Now looking for an explanation as to origin of holding power and why it can be seen in different ways.

Alot of it can be explained by the simple principle that electric charges attract and repel. - now we neeed to know something about the nature of atoms.

Here we present the pre-16 model of the atom - protons, neutrons and electrons, shells - (include  images of the models) Highlight the forces of attraction within the atoms

Link to the periodic table course - to find out how scientists came up with this model historically.

Looking at trends and patterns in the perodic table supports this - atomic radii.

Attractions between atoms

http://www.rsc.org/eic/2014/03/chemical-bonding-misconceptions-electrostatics