Dot and cross diagrams help us to model when ions are formed from atoms. Here’s an example using sodium and chlorine. They form ions which bond to form sodium chloride. 2. Work out how many ...

The basis is two ions, a sodium cation and a chlorine anion. The crystal lattice parameter is 0.563 nm. The diagram shows both a unit cell with ion locations indicated (a) and a space filling model (b ...