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 all of the orbitals in the $n = 3$ shell of an atom?

Accepted Answer

$18$

Question 3

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

Accepted Answer

$\mathrm{K}^+$

Question 4

Which of the following electron configurations represents an excited state of a carbon atom?

Accepted Answer

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

Question 5

Which statement best explains why $\mathrm{O}_2$ is paramagnetic while $\mathrm{N}_2$ is diamagnetic?

Accepted Answer

$\mathrm{O}_2$ has unpaired electrons in its molecular orbitals, while $\mathrm{N}_2$ does not.

Question 6

How many orbitals are there in the $4d$ subshell?

Accepted Answer

$5$

Question 7

Which of the following elements has the ground state electron configuration $[\mathrm{Ne}]\ 3s^2\ 3p^3$?

Accepted Answer

Phosphorus ($\mathrm{P}$)

Question 8

A certain ion has the electron configuration $1s^2\ 2s^2\ 2p^6$. Which of the following could it be?

Accepted Answer

$\mathrm{Na}^+$

Question 9

Which of the following best describes Hund’s rule?

Accepted Answer

Electrons fill degenerate orbitals singly before pairing up.

Question 10

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

Accepted Answer

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

Question 11

How many possible values of $m_l$ are there for an electron in a $d$ orbital?

Accepted Answer

$5$

Question 12

Which of the following statements about the Pauli exclusion principle is correct?

Accepted Answer

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

Question 13

Which of the following ions is isoelectronic with $\mathrm{Ne}$?

Accepted Answer

$\mathrm{F}^-$

Question 14

What is the maximum number of electrons that can occupy the $4f$ subshell?

Accepted Answer

$14$

Question 15

Which of the following electron configurations represents a transition metal ion in its most common oxidation state?

Accepted Answer

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

Question 16

A sample of an unknown element forms a $2+$ ion with the electron configuration $[\mathrm{Ar}]\ 3d^{10}$. Which element is it?

Accepted Answer

Zinc ($\mathrm{Zn}$)

Question 17

Which of the following best describes the difference between core and valence electrons?

Accepted Answer

Valence electrons are in the outermost shell and participate in bonding, while core electrons are inner electrons that do not usually participate in bonding.

Question 18

Which of the following ions has the same electron configuration as krypton ($\mathrm{Kr}$)?

Accepted Answer

$\mathrm{Br}^-$

Question 19

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number ($l$)

Question 20

A hospital patient is exposed to a photon that causes an electron in a hydrogen atom to move from $n=1$ to $n=3$. What happens to the energy of the electron?

Accepted Answer

The electron absorbs energy and moves to a higher energy level.

Quantum Numbers, Atomic Orbitals, and Electron Configurations

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