Question 1

Which of the following statements best explains why sodium (Na) forms a cation while chlorine (Cl) forms an anion in the formation of NaCl?
Correct answer: Sodium has a lower electronegativity and loses an electron to achieve a stable octet, while chlorine has a higher electronegativity and gains an electron to complete its octet.

Accepted Answer

Sodium has a lower electronegativity and loses an electron to achieve a stable octet, while chlorine has a higher electronegativity and gains an electron to complete its octet.

Question 2

Which of the following Lewis dot symbols correctly represents the oxide ion (O²⁻)?
Correct answer: O with eight dots around it and a 2− charge

Accepted Answer

O with eight dots around it and a 2− charge

Question 3

Which of the following molecules is expected to have the largest dipole moment?
Correct answer: HCl

Accepted Answer

HCl

Question 4

A student draws the Lewis structure for the nitrate ion (NO₃⁻) and assigns formal charges. Which of the following is the correct formal charge on the central nitrogen atom?
Correct answer: +1

Accepted Answer

+1

Question 5

Which of the following best describes metallic bonding in copper (Cu)?
Correct answer: Copper atoms are surrounded by a 'sea' of delocalized valence electrons that move freely throughout the metal lattice.

Accepted Answer

Copper atoms are surrounded by a 'sea' of delocalized valence electrons that move freely throughout the metal lattice.

Question 6

Which of the following pairs of elements is most likely to form an ionic bond?
Correct answer: Sodium and fluorine

Accepted Answer

Sodium and fluorine

Question 7

Which statement about the octet rule is correct?
Correct answer: Main group elements tend to achieve eight valence electrons, but some can have incomplete or expanded octets.

Accepted Answer

Main group elements tend to achieve eight valence electrons, but some can have incomplete or expanded octets.

Question 8

Given the following electronegativity values: H (2.1), C (2.5), N (3.0), O (3.5), which bond is the most polar?
Correct answer: O–H

Accepted Answer

O–H

Question 9

Which of the following best explains why water (H₂O) is a polar molecule?
Correct answer: The O–H bonds are polar and the molecule has a bent shape, resulting in a net dipole moment.

Accepted Answer

The O–H bonds are polar and the molecule has a bent shape, resulting in a net dipole moment.

Question 10

A student is asked to draw the Lewis dot symbol for the magnesium ion (Mg²⁺). Which of the following is correct?
Correct answer: Mg with no dots and a 2+ charge

Accepted Answer

Mg with no dots and a 2+ charge

Question 11

Which of the following molecules contains only nonbonding (lone pair) electrons on the central atom?
Correct answer: Cl⁻

Accepted Answer

Cl⁻

Question 12

Which of the following best describes the difference between bonding and nonbonding electrons in a Lewis structure?
Correct answer: Bonding electrons are shared between atoms, while nonbonding electrons are not shared and belong to a single atom.

Accepted Answer

Bonding electrons are shared between atoms, while nonbonding electrons are not shared and belong to a single atom.

Question 13

Which of the following compounds is expected to have the most ionic character?
Correct answer: NaCl

Accepted Answer

NaCl

Question 14

A molecule has a central atom with five bonds and one lone pair. Which of the following elements is most likely the central atom, and what does this suggest about the octet rule?
Correct answer: Phosphorus; it can have an expanded octet.

Accepted Answer

Phosphorus; it can have an expanded octet.

Question 15

Which of the following best describes the trend in electronegativity across the periodic table?
Correct answer: Electronegativity decreases down a group and increases across a period.

Accepted Answer

Electronegativity decreases down a group and increases across a period.

Question 16

Which of the following is the correct calculation for the formal charge on the oxygen atom in the hydroxide ion (OH⁻)?
Correct answer: 6 − (4 + 2) = 0

Accepted Answer

6 − (4 + 2) = 0

Question 17

Which of the following best explains why solid sodium chloride (NaCl) does not conduct electricity, but molten NaCl does?
Correct answer: In solid NaCl, ions are fixed in place and cannot move, but in molten NaCl, ions are free to move and carry charge.

Accepted Answer

In solid NaCl, ions are fixed in place and cannot move, but in molten NaCl, ions are free to move and carry charge.

Question 18

Which of the following best describes the bonding in a molecule of O₂?
Correct answer: O₂ is held together by a double covalent bond formed by sharing four electrons.

Accepted Answer

O₂ is held together by a double covalent bond formed by sharing four electrons.

Question 19

Which of the following best explains why graphite (a form of carbon) conducts electricity, while diamond (another form of carbon) does not?
Correct answer: Graphite has delocalized electrons due to its structure, allowing conductivity, while diamond has localized electrons in covalent bonds.

Accepted Answer

Graphite has delocalized electrons due to its structure, allowing conductivity, while diamond has localized electrons in covalent bonds.

Question 20

Which of the following best describes the polarity of the molecule carbon dioxide (CO₂)?
Correct answer: CO₂ is nonpolar because the molecule is linear and the bond dipoles cancel each other out.

Accepted Answer

CO₂ is nonpolar because the molecule is linear and the bond dipoles cancel each other out.

Chemical Bonding and Lewis Structures Overview

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