Question

Write a full set of quantum numbers for the following:
(a) The outermost electron in an Li atom
(b) The electron gained when a Br atom becomes a Br⁻ ion
(c) The electron lost when a Cs atom ionizes
(d) The highest energy electron in the ground-state B atom

Answer 1

Explanation:

It is known that the maximum value of ml is equal to the vale of l. But the minimum value of n is as follows.

                    n = l + 1

where,     n = principle quantum number  

                l = azimuthal quantum number

Values of n can be 1, 2, 3, 4 and so on. Whereas the values of l is 0 for s, 1 for p, 2 for d, 3 for f, and so on.

Also, "m" is known as magnetic quantum number whose values can be equal to -l and +l.

• Electronic configuration of Li is $1s^{2}2s^{1}$. So here, n = 2, l = 0, m = 0 and s = ± $\frac{1}{2}$.

• Electronic configuration of $Br^{-}$ is $[Ar]3d^{10}4s^{2}4p^{6}$. So here, n = 4, l = 1, m = -1, 0, +1, and s = ± $\frac{1}{2}$.

• Electronic configuration of $Cs^{+}$ is $[Kr]4d^{10}5s^{2}5p^{6}$. So here, n = 5, l = 1, m =  -1, 0, +1, and s = ± $\frac{1}{2}$.

• Electronic configuration of B is $1s^{2}2s^{2}2p^{1}$. So here, n = 2, l = 1, m = -1, 0, +1, and s = ± $\frac{1}{2}$.