Atoms contain protons, neutrons and electrons. The electrons are arranged in shells around the nucleus. The periodic table is a chart of all the elements arranged in increasing atomic number.
Atoms contain three sub-atomic particles called protons, neutrons and electrons.
The protons and neutrons are found in the nucleus at the centre of the atom. The nucleus is very much smaller than the atom as a whole. The electrons are arranged in shells around the nucleus.
Particle | Relative mass | Relative charge |
---|---|---|
Proton | 1 | +1 |
Neutron | 1 | 0 |
Electron | \[\frac{1}{1836}\] | -1 |
The number of electrons in an atom is always the same as the number of protons, so atoms are electrically neutral overall.
Atoms can lose or gain electrons. When they do, they form charged particles called ions: