A dot and cross diagram can show the bonding in a small molecule:
For example, a hydrogen molecule, H2, forms when two hydrogen atoms each share their outer electron.
An ammonia molecule, NH3, forms when one nitrogen atom shares its outer electrons with three hydrogen atoms. There are two types of dot and cross diagram - one without circles, and one with.
A structural formula shows the bonds between the atoms in a molecule. In these formulae:
For example, an ammonia molecule has three covalent bonds. The diagram shows its structure.
The structure of a small molecule can also be shown as a three-dimensional ball and stick model. These models show how the atoms and bonds are arranged in space. The diagram shows a ball and stick model of ammonia.
Give one advantage and one limitation of using a dot and cross diagram to represent a molecule.
A dot and cross diagram shows the pairs of outer electrons, and which atoms they have come from. It does not show how the atoms are arranged in space.
Give one advantage and one limitation of using a structural formula to represent a molecule.
The structural formula shows the bonds between the atoms, but it does not show which atoms the electrons in the bonds have come from.