Atomic+Structure

Atoms are made up of three main particles. These are the neutron, electron, and proton. This picture shows the placement of each of the main particles.

Proton - positively charged and is in the nucleus. Neutron - has no electrical charge and is in the the nucleus. Electron - moves around the nucleus and it has a negative charge.

The proton and the neutron are very large and make up most of the mass of the atom. The electrons have very little mass, but since they move around the nucleus they take up most of the space in the atom.

The electrons are located on the shells of the atom. a maximum of 2 electrons can fit on the first shell, 8 on the second shell and 8 on the third shell. the atomic number of an element an be used to write the electron configuration, which is the order of electrons as they appear on the shells. For example, the atomic number of lithium is 3, so electron configuration=2,1. 2 electrons fit on the 1st shell and 1 is left over so it fits on the 2nd shell. The atomic number of calcium is 20, so electron configuration =2,8,8,2 as 2 electrons fit on the first shell, 8 on the 2nd, 8 on the 3rd and 2 is left to fitt on the 4th shell.
 * Electron configuration**