$$\text{Predicted number of bonds} = 8 - 6 = 2$$

$$\text{Number of bonds} = 8 - \text{number of valence electrons}$$

Question 1

Which of the following statements best describes a covalent bond?

Accepted Answer

A covalent bond is a two-electron bond in which the bonding atoms share the electrons.

Question 2

How many covalent bonds and lone pairs does a nitrogen atom typically form in a neutral molecule?

Accepted Answer

Nitrogen forms 3 covalent bonds and has 1 lone pair.

Question 3

What is the predicted number of covalent bonds for an atom with 6 valence electrons?

Accepted Answer

$$	ext{Predicted number of bonds} = 8 - 6 = 2$$

Question 4

Which of the following molecules is an example of a molecule with a trigonal planar geometry?

Accepted Answer

H$$_2CO$$

Question 5

What is the bond angle in a molecule with a tetrahedral geometry?

Accepted Answer

$$109.5^\circ$$

Question 6

Which of the following is the correct Lewis structure for water (H$$_2O$$)?

Accepted Answer

O atom with two single bonds to H and two lone pairs on O

Question 7

Which of the following molecules is nonpolar?

Accepted Answer

CO$$_2$$

Question 8

What is the correct name for the compound N$$_2O$_4$$?

Accepted Answer

Dinitrogen tetroxide

Question 9

Which of the following best explains why the molecule NF$$_3 is $$polar?

Accepted Answer

NF$$_3$$ has polar bonds and a trigonal pyramidal geometry, so the dipoles do not cancel.

Question 10

Which of the following statements about resonance structures is correct?

Accepted Answer

Resonance structures are two or more Lewis structures with the same arrangement of atoms but different arrangements of electrons.

Question 11

A molecule has three groups around the central atom. What is its expected geometry and bond angle?

Accepted Answer

Trigonal planar, $$120^\circ$$

Question 12

Which of the following bonds is considered nonpolar based on electronegativity differences?

Accepted Answer

C–C

Question 13

How many total valence electrons are present in the polyatomic ion CN$$^-$$?

Accepted Answer

$$10$$

Question 14

Which of the following molecules has a bent geometry?

Accepted Answer

H$$_2O$$

Question 15

Which of the following is the correct formula for the number of bonds an atom will form, given its number of valence electrons?

Accepted Answer

$$	ext{Number of bonds} = 8 - 	ext{number of valence electrons}$$

Question 16

Which of the following molecules contains a polar covalent bond but is nonpolar overall?

Accepted Answer

CO$$_2$$

Question 17

Which of the following is an exception to the octet rule?

Accepted Answer

BF$$_3$$

Question 18

What is the molecular geometry of ammonia (NH$$_3$$)?

Accepted Answer

Trigonal pyramidal

Question 19

Which of the following best describes the electron arrangement in a double bond?

Accepted Answer

A double bond contains four electrons in two 2-electron bonds.

Question 20

Which of the following molecules is classified as polar?

Accepted Answer

NF$$_3$$

Covalent Compounds: Bonding, Structure, and Properties 4

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