# Quiz - Quantum theory & Atomic structure | Quantum Theory and Atomic Structure

1

Which of the following sets of quantum numbers (n, l, ml) is not allowed?

(2, 1, -2) ⇒ n = 2; l = 0, 1; ml = -1, 0, 1 but -2 is not allowed

2

Which electrons are most likely to be involved in chemical reactions?

Core electrons = electrons in inner energy levels = nearest to the nucleus = the most attracted by the nucleus = least likely to be involved in chemical reactions

3

What does the Pauli Exclusion Principle state?

Pauli Exclusion Principle: 2 electrons in the same atom cannot have the same set of 4 quantum numbers (n, l, ml, ms)

4

What is the maximum number of electrons that can be accommodated in a sublevel for which l = 2?

l = 2 ⇒ d orbital

⇒ ml = -2, -1, 0, 1, 2 ⇒ 5 d orbitals ⇒ 10 electrons can be accommodated

5

What is the ground state electron configuration of nickel (Z=28)?

For the electron configuration, we can use an abbreviated form by using [previous nearest noble gas] for the valence electrons.

6

How many unpaired electrons are there in the ground state of cobalt (Z=27)?

Co (Z =27): [Ar]4s2 3d7

4s: 1 orbital filled with 2 electrons,

3d: 5 orbitals with 7 electrons ⇒ we place one electron in each orbital with parallel spin (5 electrons) then we add 1 electron in 2 orbitals with opposite spin ⇒ 3 electrons stay unpaired