Atoms are the building blocks of life. There are about 110 different types of atoms called elements.
- Neutrons - which have a neutral charge.
- Electrons - which have a negative charge.
The protons and neutrons are found in the nucleus of the atom (in the centre) and the electrons orbit the atom in shells. In an atom, the number of protons is the same as the number of electrons. The electrons fill the shells in a set order starting from the first (inside) shell and working outwards...- The first shell holds up to 2 electrons.
- The second shell holds up to 8 electrons.
- The third shell holds up to 8 electrons.
- The fourth shell holds up to 18 electrons.
Each atom (or element) has a different atomic or proton number (a different number of protons).
Click on the diagram below (from www.footprints-science.co.uk) to label the parts of an atom.