Describe an atom in terms of its sub-atomic particles and their relative mass, relative charge and its location

An atom is made up of 3 sub-atomic particles: the proton, neutron and electron. A proton has a relative mass of 1, a relative charge of +1 and is located in the nucleus. A neutron has a relative mass of 1, a relative charge of 0 and is located in the nucleus. An electron has a relative mass of 1/2000, a relative charge of -1 and is located in shells surrounding the nucleus