Steve Marsden’s

It is estimated that there are upwards of 500,000 inorganic chemical compounds and well over one million organic compounds known.

How is it that atoms are able to join together and form these substances?

The apparent effect on the electron structure of an atom is more or less the same regardless of exactly how a chemical bond is formed. In its simplest terms, a chemical bond forms when A SIMULTANEOUS ATTRACTION EXISTS BETWEEN THE ELECTRONS AND NUCLEI OF TWO OR MORE ATOMS. The "strongest" chemical bonds are those which result in the formation of noble gas structures (octets) for the atoms involved.

Another way of putting this is that atoms tend to gain, lose or share electrons until their original valence levels are either full or empty.

We have already seen how Lewis structures can be used to represent simple bonding schemes.