02.03 Atoms

Atoms are the simplest structures which make up all matter. They are very, very small! Atoms are made up of a central nucleus which contains positive particles, neutral particles and orbiting electrons, whichcarry a negative charge. Different atoms have a different number of electrons, which can sometimes move between atoms.

Atoms that lose or gain electrons are called ions (Figure 2.2). Ions are very important in maintaining various processes within our body. For example, electrical signalling within some cells in our body is driven by a gradient in concentration of two different ions, sodium (Na+) and potassium (K+).

Figure 2.2 A sodium (Na) atom can lose an electron to form an ion (Na+) (Copyright, QUT)