Q: What is the formula weight of $\mathrm{MgCl_2}$? (Atomic weights: Mg = 24.3 u, Cl = 35.5 u)

$24.3 + 2 \times 35.5 = 95.3\ \mathrm{u}$

Question 1

Which of the following best explains why sodium (Na) forms a $\mathrm{Na^+}$ ion when reacting with chlorine (Cl) to form sodium chloride ($\mathrm{NaCl}$)?

Accepted Answer

Sodium loses one electron to achieve the same electron configuration as neon.

Question 2

Which of the following is the correct Lewis structure for a beryllium (Be) atom?

Accepted Answer

Be with two dots around the symbol

Question 3

A molecule of carbon dioxide ($\mathrm{CO_2}$) is described as:

Accepted Answer

A linear molecule because the central carbon has two regions of electron density

Question 4

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

Accepted Answer

$\mathrm{NaNO_3}$

Question 5

What is the formula for the ionic compound formed between aluminum ions ($\mathrm{Al^{3+}}$) and sulfide ions ($\mathrm{S^{2-}}$)?

Accepted Answer

$\mathrm{Al_2S_3}$

Question 6

Which of the following statements about VSEPR theory is correct?

Accepted Answer

It predicts the arrangement of atoms in a molecule based on the repulsion between electron pairs.

Question 7

Which of the following best describes the bonding in a molecule of $\mathrm{H_2O}$?

Accepted Answer

Two polar covalent bonds and two lone pairs on the central atom

Question 8

Which of the following is the correct name for the compound $\mathrm{N_2O_5}$?

Accepted Answer

Dinitrogen pentoxide

Question 9

Which of the following best explains why solid sodium chloride ($\mathrm{NaCl}$) has a high melting point?

Accepted Answer

It is composed of ions held together by strong electrostatic forces in a crystal lattice.

Question 10

Which of the following is a network solid?

Accepted Answer

Diamond

Question 11

What is the formula weight of $\mathrm{MgCl_2}$? (Atomic weights: Mg = 24.3 u, Cl = 35.5 u)

Accepted Answer

$24.3 + 2 	imes 35.5 = 95.3\ \mathrm{u}$

Question 12

Which of the following best describes the difference between a polar and a nonpolar covalent bond?

Accepted Answer

A polar covalent bond involves unequal sharing of electrons, while a nonpolar covalent bond involves equal sharing.

Question 13

Which of the following molecules is nonpolar?

Accepted Answer

$\mathrm{Br_2}$

Question 14

Which of the following is the correct formula for the compound formed between potassium ions ($\mathrm{K^+}$) and phosphate ions ($\mathrm{PO_4^{3-}}$)?

Accepted Answer

$\mathrm{K_3PO_4}$

Question 15

Which of the following best describes hydrogen bonding?

Accepted Answer

An attractive force between a hydrogen atom covalently bonded to O, N, or F and another electronegative atom

Question 16

Which of the following is the correct name for $\mathrm{Mg_3N_2}$?

Accepted Answer

Magnesium nitride

Question 17

A sample contains $1.00$ mol of $\mathrm{CO_2}$. What is its mass in grams? (Molecular weight of $\mathrm{CO_2}$ is $44.0$ u)

Accepted Answer

$44.0$ g

Question 18

Which of the following best describes the electron arrangement around the central atom in ammonia ($\mathrm{NH_3}$) according to VSEPR theory?

Accepted Answer

Four pairs of electrons arranged in a tetrahedral geometry

Question 19

Which of the following is a correct statement about polyatomic ions?

Accepted Answer

They are covalently bonded groups of atoms that carry a net charge.

Chapter 4: Forces Between Particles – Ionic and Covalent Bonding, Lewis Structures, and Molecular Shapes

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