Covalent bonding

An ionic bond was described in previous posts on this blog. Now I want to focus on a covalent bond. This is different from an ionic bond in that it is not an attraction of a positive and negative charge on two atoms.

Notice how in these covalently bonded molecules above, the atoms of the basic unit have a distinct shape with bond angles. These distinct molecules are generally not held together in a rigid lattice structure (at room temperature) that looks like this: (for ionic bonding)

The structures in green, red and black are ionically bonded lattice structures while the sulfur dioxide and carbon dioxide above covalently bonded shapes.

If you put them next to each other (to compare) they look like this (see below):

Can you tell which structures are ionic lattices and which are covalent? In the final diagram the two structures are mixed together.