A atom is a small particle of an element which still has the chemical properties of an element. Atoms are made up of 3 simple things: Protons, Neutrons and Electrons.
All atoms contain a very small nucleus. The nucleus contains Protons and Neutrons. Electrons will be found outside the nucleus with shells. A atom has a equal number of Protons and Electrons.
E.g Na has a mass number of 23 (p+n) and a atomic number of 11.
Isotopes are atoms of the same element with the same atomic number but different mass number. They have the same number of protons but different numbers of Neutrons. They have the same chemical properties as they have the same number of electrons. They have different physical properties as they…