Question 1

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from a metal to a non-metal, resulting in electrostatic attraction between oppositely charged ions.

Question 2

What is the chemical formula for the compound formed when calcium reacts with oxygen, and why?

Accepted Answer

CaO, because calcium loses two electrons to become Ca$$^{2+}$$ and oxygen gains two electrons to become O$$^{2-}$$, resulting in a 1:1 ratio for electrical neutrality.

Question 3

Which of the following molecules is an example of a molecular element?

Accepted Answer

N$$_2$$

Question 4

According to the Lewis theory of bonding, why do atoms form chemical bonds?

Accepted Answer

To achieve a full valence shell of electrons, becoming isoelectronic with noble gases.

Question 5

Which rule explains why hydrogen atoms form stable molecules when they share two electrons?

Accepted Answer

Duet rule

Question 6

What is the total number of valence electrons in a molecule of formaldehyde (H$$_2CO$$)?

Accepted Answer

$$12$$

Question 7

Which of the following statements about the octet rule is correct?

Accepted Answer

Atoms of period 2 non-metals tend to form the most stable substances when surrounded by eight valence electrons.

Question 8

Which molecule is an example of an exception to the octet rule due to an underfilled octet?

Accepted Answer

BF$$_3$$

Question 9

Why can sulfur in SF$$_6$$ have more than eight electrons in its valence shell?

Accepted Answer

Because sulfur can use vacant 3d orbitals to accommodate extra electrons.

Question 10

Which of the following best describes a coordinate covalent bond?

Accepted Answer

A bond in which both electrons in the bond are donated by the same atom.

Question 11

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

Accepted Answer

NH$$_4NO$_3$$

Question 12

What is the main reason that ionic compounds like NaCl have high melting points?

Accepted Answer

They are held together by strong electrostatic attractions between oppositely charged ions.

Question 13

Which of the following is the correct Lewis structure for the nitrate ion, NO$$_3^-$$?

Accepted Answer

A structure with nitrogen in the center, three oxygens around it, one double bond, two single bonds, and a total of 24 valence electrons, with brackets and a negative charge.

Question 14

Which of the following best explains why molten aluminum oxide conducts electricity, but solid aluminum oxide does not?

Accepted Answer

In the molten state, ions are free to move and carry charge, while in the solid state, ions are fixed in place.

Question 15

Which of the following is a correct step when drawing a Lewis structure for a polyatomic ion?

Accepted Answer

Add one electron for each unit of negative charge.

Question 16

Which of the following molecules contains a central atom with an overfilled octet?

Accepted Answer

PCl$$_5$$

Question 17

What is the main difference between a Lewis structure and a simplified Lewis structure?

Accepted Answer

A Lewis structure uses dots for lone pairs and bonding pairs, while a simplified Lewis structure uses lines for bonds and dots for lone pairs.

Question 18

Which of the following best describes the arrangement of ions in a crystal lattice of NaCl?

Accepted Answer

Each Na$$^+$$ ion is surrounded by six Cl$$^-$$ ions, and each Cl$$^-$$ ion is surrounded by six Na$$^+$$ ions.

Question 19

Which of the following is true about lone electron pairs?

Accepted Answer

They are pairs of valence electrons localized to a given atom and not involved in bonding.

Lesson 4.1: Types of Chemical Bonds and Lewis Structures

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