Explain the nuclear model

The atom consists of three sub-atomic particles: Protons; Neutrons and electrons. Protons and neutrons are in the nucleus of the atom and the electrons occupy the electron shells around the nucleus.

Electrons have a relative mass of 1/1836, they arent considered to add to the relative weight of the atom.Protons and neutrons have a relative mass of 1. It is the mass of the nucleus that creates the atomic weight of the atom. This is used to identify elements in the periodic table. It is the top number on each element on the GCSE periodic table. The bottom number is the proton number. To get the neutron number: Atomic Mass- Proton number= Neutron number. Some atoms of an element will have a higher atomic mass but the same proton number and electron number. Remember the proton number and electron number is the defining feature of an element. Therefore, when the atomic mass is higher it is becasue there is a higher number of neutrons. These are called isotopes. Carbon for example has ¹³C and ¹⁴C isotopes. The ¹⁴C isotope has one more neutron.

Protons have a positive charge, neutrons have a neutral charge and electrons have a negative charge. This means that when an atom looses electrons it becomes more positive and when it gains electrons it becomes more negative. This is what creates ions. Metals loose electrons becoming positive ions and non-metals gain electrons become negative ions.