Question

Write all four quantum no of valence electron rb

Answer 1

Correct set of four quantum numbers for the valence (outermost) electron of Rubidium (Z=37) is :

1) 5, 0, 0, +½

2) 5, 1, 0, +½

3) 5, 1, 1, +½

4) 6, 0, 0, +½

Logic:

We may write the electronic configuration of Rubidium, Rb and then find out the quantum numbers for the last electron.

Or

Remember that, Rb belongs to alkali metals (1st group) and 5th period of modern periodic table. For alkali metals, the outer electronic configuration is ns1 and for the 5th period n = 5.

Solution:

Electronic configuration of Rb = 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1

Check that there are 37 electrons.

Therefore,

Principal quantum number, n = 5

Azimuthal quantum number, l = 0 (since for s orbital l = 0)

Magnetic quantum number, m = 0 (since for l = 0, there is only one m value i.e. 0)

Spin quantum number, s = +½ or -½ (there is only one electron and it can have clockwise or anticlockwise spins)

Conclusion:

The correct set of quantum numbers will be: 5, 0, 0, +½ or -½. Therefore correct option is 1.