Question

7. Write n, l, ml, ms values of
4th and 7th electron of oxygen
element. (2M)​

Answer 1

Then you use the Aufbau Principle, the Pauli Exclusion Principle, and Hund's Rule to assign the quantum numbers.

The rules for quantum numbers are:

n=1,2,3…∞.

l=0,1,2…n–1

ml=−l…−1,0,1…l

ms=±12

No two electrons can have the same set of four quantum numbers.

According to the Aufbau Principle, electrons fill orbitals starting at the lowest possible energy levels.

So the first two electrons have the quantum numbers

nlmlms10i0+1210i0−12

The Pauli Exclusion Principle states that no two electrons in the same atom can have the same set of four quantum numbers.

So the next two electrons have the quantum numbers

nlmlms20i0+1220i0−12

Now Hund's Rule comes into effect.

Hund's Rule states that if two or more orbitals of equal energy are available, electrons will occupy them singly and with the same spin before filling them in pairs.

The next four electrons have the quantum numbers

nlmlms21−1+1