Return to Contents Chapter 1: Structure Determines Properties Ch 1 contents
All matter is composed of atoms.   Atoms are an ordered collection of various subatomic particles.  The central nucleus contains the protons and neutrons, around this are the all important electrons.

The simple schematic diagram to the left shows this simple model of a helium atom. The nucleus contains two protons and two neutrons, and then there are two electrons.

You should be familiar with the subatomic particles and how to determine how many of each a specific atom has. 

schematic diagram of a helium atom

In introductory organic chemistry courses, the majority of the compounds you will encounter are based on a limited selection of atoms : the atoms of greatest interest are H, C, N, O, and the halogens F, Cl, Br, I  plus a few others such as Li, Na, Mg, Al, B, P, S. Later, when one probes deeper into more advanced synthetic methods, one needs to be familiar with many more elements.

Try the questions about atoms.  If you are not comfortable with these you should look at a bit more detail.

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organic chemistry © Dr. Ian Hunt, Department of Chemistry University of Calgary