Dot and cross diagrams
A dot and cross diagram can model the bonding in a simple molecule:
- the outer shell of each atom is drawn as a circle
- circles overlap where there is a covalent bond
- electrons from one atom are drawn as dots, and electrons from another atom as crosses
For example, a hydrogen molecule forms when a hydrogen atom shares its outer electron with another hydrogen atom.
A simple molecule can be modelled by drawing its structure. In these structures:
- show each atom by its element symbol
- show each covalent bond as a straight line
For example, a hydrogen molecule has two H atoms and one covalent bond. The diagram shows its structure.
Some examples of models