Nuclear Chemistry

Author: Andrew R. Barron

Everything around us is made from the elements of the periodic table. Elements are defined as the fundamental substances of chemistry, composed of atoms, in which all the atoms are the same. In turn, atoms are defined as being the smallest units of matter and cannot be further divided by ordinary means. It is the phrase “ordinary means” that is key to our discussions of nuclear chemistry.

Figure 2: John Dalton (1766-1844) from an engraving by Worthington.

Before we can study the elements it is worth asking two fundamental questions:

• Why are there so many elements?
• How did they come into existence?

To answer these questions we need to consider two areas.

1. Dalton’s view of the atom.
2. The study of Alchemy.

Although Democritus first suggested the existence of the atom, it took almost two millennia before the atom was placed on a solid foothold as a fundamental chemical object by the English chemist John Dalton. Although two centuries old, Dalton's atomic theory remains basically valid in modern chemical thought. Dalton’s atomic theory states that:

• All matter is made of atoms. Atoms are indivisible and indestructible.
• All atoms of a given element are identical in mass and properties.
• Compounds are formed by a combination of two or more different kinds of atoms.
• A chemical reaction is a rearrangement of atoms.

We will try and understand these and along the way we will understand more about the atom.