Draw a sketch of Bohr’s model of an atom with three shells.
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Solution
Bohr's model of atom:
The Bohr model of the atom was proposed by Neil Bohr in 1915. It came into existence with the modification of Rutherford’s model of an atom. Rutherford’s model introduced the nuclear model of an atom, in which he explained that a nucleus (positively charged) is surrounded by negatively charged electrons.
Postulates of Bohr's model of an atom:
In an atom, electrons (negatively charged) revolve around the positively charged nucleus in a definite circular path called orbits or shells.
Each orbit or shell has a fixed energy and these circular orbits are known as orbital shells.
The energy levels are represented by an integer (n=1, 2, 3…) known as the quantum number. This range of quantum number starts from nucleus side with n=1 having the lowest energy level. The orbits n=1, 2, 3, 4… are assigned as K, L, M, N…. shells and when an electron attains the lowest energy level, it is said to be in the ground state.
The electrons in an atom move from a lower energy level to a higher energy level by gaining the required energy and an electron moves from a higher energy level to lower energy level by losing energy.
