Aim:- To understand the basic atomic structure (Bohr Atom model), Sub atomic particles like Proton, Electron, Neutron and their Electrical properties.


In 1913 Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus. The motion of the electrons in the Rutherford model was unstable because, according to classical mechanics and electromagnetic theory, any charged particle moving on a curved path emits electromagnetic radiation; thus, the electrons would lose energy and spiral into the nucleus. To remedy the stability problem, Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy. The energy of an electron depends on the size of the orbit and is lower for smaller orbits. Radiation can occur only when the electron jumps from one orbit to another. The atom will be completely stable in the state with the smallest orbit, since there is no orbit of lower energy into which the electron can jump.



  1. Nucleus:- The part of atom which contains proton and neutron. This part is the place where total mass is concentrated.



2. Protons:- These are positively charged particles which are confined inside the Nucleus.

3. Neutrons:- These particles are neutral in charge but having a mass equal to the protons and are situated inside Nucleus.

4. Electrons:- These particles are having equal but opposite charge of protons. The number of electrons must be equal to the number of protons so that the atoms becomes neutral in terms of electrical charge.

5. Orbits:- The path through which the electrons revolve round the nucleus are known as orbits. The orbits can accommodate the electrons in the order of 2, 8, 18,32 etc.