Atoms and Reactions

Atomic Structure

The nucleus of an atom contains positively charged protons and neutrons which do not have a charge. Negative charge electrons orbit the nucleus in orbits or shells. Atoms do not have an overall charge because the number of positive protons and negative electrons are the same.

The number of protons is also known as the atomic number- this will also be the same as the number of negative electrons. The atomic mass is the number of protons plus the number of neutrons in the nucleus. We can work out the number of neutrons by deducting the number of protons (atomic number) away from the atomic mass.

Ex. Phosphorus (P) has an atomic mass of 31 and an atomic number of 15. This means there are 15 positive protons and 15 negative electrons in a phosphorus atom.

Atomic mass…