Class 9 Science
Neils Bohr, a Danish physicist, in 1913 proposed model of atom which rectified the problems left by Rutherford’s Model. He proposed that
The circular path around the nucleus is called orbit, energy level or shell. Energy level are represented by letter – K, L, M, N, …. and so on.
Therefore,
The orbits are denoted by 1, 2, 3, …. and so on.
The distribution of electrons in an orbit can be obtained by using formulae 2n 2
where ‘n’ is number of orbit.
Here n = 1
Therefore,
`2n^2 = 2 xx 1^2 = 2`
Thus, maximum number of electrons in K-shell i.e. 1st shell = 2
Here n = 2, therefore,
`2n^2= 2 xx 2^2= 8`
Thus, maximum number of electrons in L-shell = 8
Here n = 3, therefore,
`2n^2= 2 xx 3^2= 18`
Thus, maximum number of electrons in M-shell = 18
Here n = 4, therefore,
`2n^2= 2 xx 4^2= 32`
Thus, maximum number of electrons in N-shell = 32
Here n = 5, therefore,
`2n^2= 2 xx 5^2= 50`
Thus, maximum number of electrons in O-shell = 50
Here n = 6, therefore,
`2n^2= 2 xx 6^2 = 72`
Thus, maximum number of electrons in P-shell = 72
In similar way maximum number of electrons in any shell can be calculated.
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