Question 1

Which of the following statements best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence shell of electrons, satisfying the octet rule.

Question 2

What is the total number of valence electrons in a molecule of water ($\mathrm{H_2O}$)?

Accepted Answer

$8$

Question 3

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

Accepted Answer

$\mathrm{Na^+}$

Question 4

A calcium atom ($\mathrm{Ca}$) loses two electrons to form a $\mathrm{Ca^{2+}}$ ion. Which statement is true about this process?

Accepted Answer

The $\mathrm{Ca}$ atom becomes a cation and achieves a noble gas electron configuration.

Question 5

Which of the following compounds contains both ionic and covalent bonds?

Accepted Answer

$\mathrm{Na_2SO_4}$

Question 6

What is the correct formula for the ionic compound formed between aluminum and oxygen?

Accepted Answer

$\mathrm{Al_2O_3}$

Question 7

Which of the following molecules is nonpolar, despite having polar bonds?

Accepted Answer

$\mathrm{CO_2}$

Question 8

How many electrons are in the third energy level ($n=3$) of a phosphorus atom ($\mathrm{P}$, atomic number $15$)?

Accepted Answer

$5$

Question 9

Which of the following best describes the bond in $\mathrm{NaCl}$?

Accepted Answer

An ionic bond formed by the transfer of an electron from sodium to chlorine.

Question 10

What is the molecular shape and approximate bond angle of methane ($\mathrm{CH_4}$) according to VSEPR theory?

Accepted Answer

Tetrahedral, $109.5^\circ$

Question 11

Which of the following best explains why water ($\mathrm{H_2O}$) is a polar molecule?

Accepted Answer

It has polar bonds and a bent molecular shape, resulting in a net dipole.

Question 12

How many moles of carbon atoms are present in $24.04$ grams of carbon ($\mathrm{C}$, molar mass $12.01\ \mathrm{g/mol}$)?

Accepted Answer

$2.00$ moles

Question 13

Which of the following elements is most likely to form a $2-$ anion?

Accepted Answer

Oxygen

Question 14

A molecule of ammonia ($\mathrm{NH_3}$) has which molecular geometry and bond angle?

Accepted Answer

Trigonal pyramidal, $107^\circ$

Question 15

Which of the following best describes the octet rule?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve eight electrons in their valence shell.

Question 16

What is the molar mass of sodium chloride ($\mathrm{NaCl}$)? (Na: $22.99\ \mathrm{g/mol}$, Cl: $35.45\ \mathrm{g/mol}$)

Accepted Answer

$58.44\ \mathrm{g/mol}$

Question 17

Which of the following best describes the difference between a cation and an anion?

Accepted Answer

A cation has fewer electrons than protons, while an anion has more electrons than protons.

Question 18

Which of the following molecules would you expect to have the highest electronegativity difference between its atoms?

Accepted Answer

$\mathrm{NaCl}$

Question 19

How many atoms are present in $2.00$ moles of oxygen gas ($\mathrm{O_2}$)? (Avogadro's number $= 6.02 	imes 10^{23}$)

Accepted Answer

$2.41 	imes 10^{24}$

Question 20

Which of the following best describes the type of bonding and the resulting compound when magnesium reacts with chlorine?

Accepted Answer

Ionic bonding; magnesium donates electrons to chlorine, forming $\mathrm{MgCl_2}$.

Chapter 3: Chemical Bonding, Electron Arrangement, and Molecular Structure

Study Guide - Practice Questions