Question 1

Which of the following statements best describes the Pauli Exclusion Principle?

Accepted Answer

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

Question 2

According to Coulomb's Law, what happens to the potential energy $E$ of two oppositely charged particles as they get closer together?

Accepted Answer

The potential energy decreases.

Question 3

Which quantum number is associated with the orientation of an electron's spin?

Accepted Answer

Spin quantum number $m_s$

Question 4

Which of the following electron configurations represents the element magnesium (Mg, atomic number 12)?

Accepted Answer

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

Question 5

Which of the following best explains why the 2s orbital is lower in energy than the 2p orbital in multi-electron atoms?

Accepted Answer

The 2s orbital penetrates closer to the nucleus and is less shielded from nuclear charge.

Question 6

Which set of quantum numbers is possible for an electron in a 4s orbital?

Accepted Answer

$n=4,\ l=0,\ m_l=0,\ m_s=+\frac{1}{2}$

Question 7

A transition metal ion has the electron configuration $[Ar] 3d^6$. Which ion is this most likely to be?

Accepted Answer

Fe$^{2+}$

Question 8

Which of the following statements about Hund's Rule is correct?

Accepted Answer

Electrons occupy degenerate orbitals singly with parallel spins before pairing up.

Question 9

Which of the following is the correct order of orbital filling for the first 20 elements?

Accepted Answer

$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s$

Question 10

Which of the following best describes the concept of shielding in multi-electron atoms?

Accepted Answer

Inner electrons partially block the attraction between the nucleus and outer electrons.

Question 11

Which of the following is the electron configuration for phosphorus (P, atomic number 15)?

Accepted Answer

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

Question 12

Which of the following statements about orbital energy in multi-electron atoms is correct?

Accepted Answer

Orbitals with lower $l$ quantum numbers have lower energy within the same principal shell.

Question 13

A sulfur atom (atomic number 16) has how many unpaired electrons in its ground state?

Accepted Answer

2

Question 14

Which of the following best describes the effect of penetration on orbital energy?

Accepted Answer

Greater penetration leads to lower energy because the electron is less shielded from the nucleus.

Question 15

Which of the following is the correct electron configuration for bromine (Br, atomic number 35)?

Accepted Answer

$[Ar] 4s^2 3d^{10} 4p^5$

Question 16

Which of the following is a correct set of quantum numbers for the two electrons in a 4s orbital?

Accepted Answer

$n=4,\ l=0,\ m_l=0,\ m_s=+\frac{1}{2}$ and $n=4,\ l=0,\ m_l=0,\ m_s=-\frac{1}{2}$

Question 17

Which of the following best describes the effective nuclear charge ($Z_{eff}$) experienced by a valence electron in a multi-electron atom?

Accepted Answer

It is less than the actual nuclear charge due to shielding by inner electrons.

Question 18

A hospital is using sodium (Na) in a medical imaging procedure. What is the ground-state electron configuration for sodium?

Accepted Answer

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

lecture 10

Study Guide - Practice Questions