Question 1

Which set of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$n = 2,\ l = 2,\ m_l = 0,\ m_s = +\frac{1}{2}$

Question 2

How many electrons can occupy the 3d subshell in a neutral atom?

Accepted Answer

10

Question 3

Which element has the following ground-state electron configuration: $1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^1$?

Accepted Answer

Aluminum (Al)

Question 4

What is the electron configuration of the $\mathrm{O}^{2-}$ ion?

Accepted Answer

$1s^2\ 2s^2\ 2p^6$

Question 5

Which statement best describes Hund’s rule?

Accepted Answer

Electrons occupy orbitals of equal energy singly before pairing up.

Question 6

A sample of iron ($\mathrm{Fe}$) forms $\mathrm{Fe}^{3+}$ ions. What is the electron configuration of $\mathrm{Fe}^{3+}$?

Accepted Answer

$1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 3d^5$

Question 7

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number ($l$)

Question 8

How many orbitals are present in the $4f$ subshell?

Accepted Answer

7

Question 9

Which of the following ions is isoelectronic with argon ($\mathrm{Ar}$)?

Accepted Answer

$\mathrm{Cl}^-$

Question 10

A transition metal ion has the electron configuration $[\mathrm{Ar}]\ 3d^6$. Which ion is it?

Accepted Answer

$\mathrm{Fe}^{2+}$

Question 11

Which property is associated with substances containing unpaired electrons?

Accepted Answer

Paramagnetism

Question 12

What is the maximum number of electrons that can occupy the $n=4$ shell?

Accepted Answer

32

Question 13

Which of the following elements has a ground-state electron configuration ending in $4s^2\ 3d^{10}$?

Accepted Answer

Zinc (Zn)

Question 14

If an atom has the quantum numbers $n=3$, $l=2$, $m_l=-2$, $m_s=+\frac{1}{2}$, which orbital does the electron occupy?

Accepted Answer

3d

Question 15

Which of the following ions has a pseudo-noble gas configuration?

Accepted Answer

$\mathrm{Sn}^{4+}$

Question 16

What is the electron configuration for $\mathrm{K}^+$?

Accepted Answer

$1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6$

Question 17

Which quantum number(s) must differ for two electrons in the same orbital according to the Pauli exclusion principle?

Accepted Answer

Spin quantum number ($m_s$)

Question 18

Which subshell is being filled for elements in the lanthanide series?

Accepted Answer

$4f$

Question 19

A neutral atom has the electron configuration $1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 4s^1$. What is the element?

Accepted Answer

Potassium (K)

Question 20

Which of the following statements about noble gases is correct?

Accepted Answer

They have a full outer shell and do not tend to form ions.

Quantum Numbers, Atomic Orbitals, and Electron Configurations

Study Guide - Practice Questions