Q: Which of the following is the correct formula for calculating the formal charge on an atom?

$$\text{Formal charge} = \text{number of valence electrons} - (\text{number of nonbonding electrons} + \frac{1}{2} \times \text{number of bonding electrons})$$

Question 1

Which of the following best explains why atoms form chemical bonds?

Accepted Answer

To lower the potential energy between the charged particles that compose atoms

Question 2

Which of the following pairs of atoms will form a bond with the greatest ionic character?

Accepted Answer

Sr and F

Question 3

Given the electronegativities: Na (0.9), P (2.1), Al (1.5), N (3.0), arrange these elements in order of decreasing electronegativity.

Accepted Answer

N \u003e P \u003e Al \u003e Na

Question 4

Which of the following bonds is classified as polar covalent?

Accepted Answer

Bond with an electronegativity difference of 1.0

Question 5

What is the correct Lewis structure for the ammonium ion, $$\mathrm{NH_4$^+}$$?

Accepted Answer

A nitrogen atom with four single bonds to hydrogen, enclosed in brackets with a $$+$$ charge

Question 6

Which molecule below is expected to be a free radical?

Accepted Answer

$$\mathrm{NO}$$

Question 7

Which of the following molecules can have an expanded octet?

Accepted Answer

$$\mathrm{PF_5$}$$

Question 8

What is the molecular geometry of $$\mathrm{NH_3$}$$ according to VSEPR theory?

Accepted Answer

Trigonal pyramidal

Question 9

Which statement is always true according to VSEPR theory?

Accepted Answer

The shape of a molecule is determined by repulsions among all electron groups on the central atom.

Question 10

Which of the following best describes the bond angle in a molecule with tetrahedral electron geometry?

Accepted Answer

$$109.5^\circ$$

Question 11

A molecule has three electron groups around the central atom, one of which is a lone pair. What is the molecular geometry?

Accepted Answer

Bent

Question 12

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

Accepted Answer

$$\mathrm{CO_2$}$$

Question 13

Which of the following is the correct formula for calculating the formal charge on an atom?

Accepted Answer

$$	ext{Formal charge} = 	ext{number of valence electrons} - (	ext{number of nonbonding electrons} + \frac{1}{2} 	imes 	ext{number of bonding electrons})$$

Question 14

Which of the following best describes the trend in bond length for covalent bonds?

Accepted Answer

Bond length decreases as the number of shared electrons increases

Question 15

Which of the following molecules is expected to be polar?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 16

Which of the following best describes the effect of lone pairs on bond angles in a molecule?

Accepted Answer

Lone pairs decrease bond angles compared to the ideal geometry

Question 17

Which of the following is a correct step in writing a Lewis structure for a polyatomic ion?

Accepted Answer

Add electrons equal to the negative charge of the ion

Question 18

Which of the following statements about resonance structures is FALSE?

Accepted Answer

Resonance structures can differ in the arrangement of atoms

Question 19

Which of the following best describes the molecular geometry of $$\mathrm{SF_4$}$$?

Accepted Answer

Seesaw

Question 20

Which of the following is the best estimate for the percent ionic character of HCl(g), given a bond length of 127 pm and a moderate dipole moment?

Accepted Answer

15%

Chemical Bonding I: Lewis Structures, Bond Types, and Molecular Geometry

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