Question 1

Which quantum number defines the shape of an orbital?

Accepted Answer

Angular momentum quantum number ($l$)

Question 2

How many electrons are present in the 3p subshell in the ground state of atomic xenon ($Z=54$)?

Accepted Answer

6

Question 3

Which of the following is the correct electron configuration for sulfur ($Z=16$)?

Accepted Answer

$1s^2 2s^2 2p^6 3s^2 3p^4$

Question 4

Which element has a valence configuration of $2s^2$?

Accepted Answer

Be

Question 5

Which electron configuration violates the Pauli Exclusion Principle?

Accepted Answer

An orbital with two electrons both having spin up ($\uparrow\uparrow$)

Question 6

No two electrons within the same orbital can have the same set of quantum numbers. This statement describes:

Accepted Answer

Pauli Exclusion Principle

Question 7

According to Hund's rule, when filling degenerate orbitals, electrons will:

Accepted Answer

Fill each orbital singly with parallel spins before pairing

Question 8

Which principle explains why electrons fill the lowest energy orbitals first?

Accepted Answer

Aufbau Principle

Question 9

What is the maximum number of electrons that can occupy the $2p$ subshell?

Accepted Answer

6

Question 10

Which set of quantum numbers is not allowed for an electron in a $2p$ orbital?

Accepted Answer

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

Question 11

Which of the following best describes the Pauli Exclusion Principle?

Accepted Answer

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

Question 12

Which quantum number determines the energy level of an electron in an atom?

Accepted Answer

Principal quantum number ($n$)

Question 13

How many orbitals are in the $3d$ subshell?

Accepted Answer

5

Question 14

Which of the following elements has the electron configuration $[Ne] 3s^2$?

Accepted Answer

Magnesium

Question 15

If an atom has the electron configuration $1s^2 2s^2 2p^6 3s^2 3p^1$, what is the element?

Accepted Answer

Aluminum

Question 16

Which rule or principle is violated if two electrons in the same orbital have the same spin?

Accepted Answer

Pauli Exclusion Principle

Question 17

Which quantum number describes the orientation of an orbital in space?

Accepted Answer

Magnetic quantum number ($m_l$)

Question 18

Which of the following electron configurations represents a violation of Hund's rule?

Accepted Answer

Two electrons paired in a $2p$ orbital while other $2p$ orbitals are empty

Question 19

Which principle is most important in determining the order in which electrons fill atomic orbitals?

Accepted Answer

Aufbau Principle

Question 20

Which of the following is the correct order of filling for the first 20 electrons according to the Aufbau principle?

Accepted Answer

$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p$

Quantum Numbers, Electron Configuration, and Principles of Atomic Structure

Study Guide - Practice Questions