To understand life as we know it, we must first understand a little bit of organic chemistry. Organic molecules contain both carbon and hydrogen. While many organic chemicals also contain other elements, it is the carbon-hydrogen link that defines them as organic.
Organic chemistry defines life.
Just as there are millions of different types of living organisms on this planet, there are millions of different organic molecules, each with different chemical and physical properties. There are organic chemicals that make up your hair, your skin, your fingernails, etc. The diversity of organic chemicals is due to the versatility of the carbon atom. Let's look at its chemistry in a little more detail. Similar to other non-metals, carbon needs 8 electrons to fill its valence shell.