Question

Maximum number of electrons present in M shell is:
A. 2
B. 18
C. 32
D. 2

Answer 1

Hint: The shells are represented by the principal quantum numbers. The electrons present in a shell are double the square of principal quantum numbers. The Principal quantum number of the M shell is three. M shell has s, p, and d-orbitals.

Complete Step by step answer: In the structure of the atom, the centre is known as the nucleus. The nucleus is surrounded by the orbits having electrons are known as electron shells.
The shell closest to the nucleus is known as the K shell. The next shell is known as the L shell. The next higher shell is M and then next is known as the N shell.
The shell corresponds to the principal quantum numbers.
Shell and their principal quantum number are shown as follows:
Shell $\;\;\;$ Principle quantum number
K $\;\;\;\;\;\;$ 1
L $\;\;\;\;\;\;$ 2
M $\;\;\;\;\;\;$ 3
N $\;\;\;\;\;\;$ 4
Each shell has a fixed number of electrons. The formula to determine the number of electrons in a shell is as follows:
${\text{2(n}}{{\text{)}}^{\text{2}}}$
Where,
${\text{n}}$ is the principal quantum number
For the M shell principal quantum number is 3.
So, the maximum number of electrons is,
${\text{ = 2(3}}{{\text{)}}^{\text{2}}}$
Maximum number of electrons $ = 18$
So, the maximum number of electrons present in the M shell is $18$.

Therefore, option (B) $18$, is correct.

Note: K shell has a maximum of two electrons. L shell has a maximum of eight electrons. N shell has a maximum of thirty-two electrons. K shell has one s-orbital, so it can have a total of two electrons maximum. L shell has one s-orbital and one p-orbital. The s-orbital can have a maximum of two electrons and p-orbitals can have a maximum of six electrons, so the L shell can have a total of eight electrons. M shell has one s-orbital and one p-orbitals and d-orbitals. The s-orbital can have a maximum of two electrons, p-orbitals can have a maximum of six electrons and d-orbitals can have a maximum of ten electrons, so the M shell can have a total of eighteen electrons.