Chemistry of Life » Compounds

The clue as to why there are some many millions of substances is that the atoms of elements combine together to form compounds. There are two basic types - molecular and ionic. An example of molecular substances are water (H2O), carbon dioxide (CO2), ammonia (NH2) and hydrogen sulphide (H2S). Examples of simple ionic compounds are sodium chloride,usually known as common salt (NaCl) and calcium carbonate (CaCO2). A number of small molecules are found in living processes. Among them are Water, Carbon Dioxide, Methane, Ammonia and Hydrogen Sulphide. Important ions that are found in life processes are sodium, potassium, calcium and magnesium and the chloride ion.

Small molecules alone do not of themselves account for life. To understand life processes we must turn our attention to very large molecules known collectively as polymers. Carbohydrates and lipids are important in most living organisms but the three polymers of outstanding importance are DNA, RNA and PROTEINS. ALL living processes depend on the interaction of these three types of molecule. First we shall consider DNA and RNA.

Ray Goodwin

Somewhere there are mountains
Glistening in the snow
Somewhere there are mountains
That we shall never know

Somewhere there are rivers
Flowing fast and free
Somewhere there are rivers
That we can never see

Somewhere there are oceans
And sun drenched island sands
Forests full of creatures
In vastly distant lands

Somewhere there’s a planet
Beneath an alien star
The people watch our tiny sun
And wonder where we are

One day perhaps we’ll find them
Across the void of space
Perhaps through ways as yet unknown
We’ll meet them face to face

The author of this web site Ray Goodwin holds B.Sc. Degrees from London University in Chemistry, Geology and Physiology and an M.Sc. in Biochemistry. He has spent most of his professional life teaching in Colleges of Technology. On his retirement he has entered the fields of astronomy, astrochemistry, astrobiology and space sciences. He has spent a great deal of his retirement in visiting amateur astronomy societies and in attending European Space Agency Symposia in ESTEC in the Netherlands and other scientific conferences in England and Sweden. He regularly attends the yearly European Astrofest in South Kensington London and other meetings in the UK. He has written scientific articles and given a number of lectures on diverse scientific subjects.

Readers of this web site are invited to e-mail the author ( and discuss their opinions of the topics dealt with and suggest any changes which they think may be helpful.

Life in the Cosmos Website
Version 01.00 - April 20, 2015.