Tructure of The AtomIntroductionMatters are made of tiny particles called atom. Atom is made of three particles; electron, proton and neutron. These particles are called fundamental particles of an atom or sub atomic particles.Electron (e–) - Electron is denoted by ‘e’ and is a negatively charged particle. The absolute charge over an electron is equal to 1.6x10-19 of negative charge and is considered equal to – 1.The relative mass of electron is 1/1836. Since the mass of an electron is very small, thus it is considered equal to 0. Electrons revolve round the nucleus of atoms.Proton (p+) - Proton is denoted by ‘p’ and is positively charged particle. The absolute charge over proton is 1.6x10 -19 coulomb of positive charge and it is considered as unit positive charge. Thus absolute charge over a proton is equal to +1.The absolute mass of a proton is equal to 1.6x10 -24 g and considered equal to 1 as it is equal to the mass of 1 hydrogen atom. Proton is present in the nucleus of atom.Neutron (n) – Neutron is denoted by ‘n’ and is a neutral particle.The absolute mass of neutron is 1.6 x 10 -24 g. The relative mass of neutron is equal to 1. Neutron is presents in the nucleus of atom.Nucleus – The centre of atom is called nucleus. Nucleus comprises of neutron and proton. Nucleus of an atom contains the whole mass of an atom.