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

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

Question 1

Which of the following best describes the difference between ionic and covalent bonding?

Accepted Answer

Ionic bonding involves the transfer of electrons from one atom to another, while covalent bonding involves the sharing of electrons between atoms.

Question 2

Which of the following compounds is most likely to have the highest lattice energy?

Accepted Answer

LiCl

Question 3

What is the correct Lewis symbol for a magnesium ion, $$\mathrm{Mg$$^{2+}$$}$$?

Accepted Answer

$$\mathrm{Mg$$^{2+}$$}$$ with no dots

Question 4

Which of the following statements about lattice energy is correct?

Accepted Answer

Lattice energy increases as the charge on the ions increases and as the size of the ions decreases.

Question 5

Which of the following molecules is an example of a molecule with a polar covalent bond?

Accepted Answer

$$\mathrm{HF}$$

Question 6

How many valence electrons are present in the Lewis structure of $$\mathrm{$$PCl_3$$}$$?

Accepted Answer

26

Question 7

Which of the following best explains why $$\mathrm{BF_3$}$$ does not have a complete octet on the boron atom in its dominant Lewis structure?

Accepted Answer

Adding electrons to complete boron's octet would place a negative formal charge on boron and a positive formal charge on fluorine, which is not favorable.

Question 8

Which of the following is the correct formula for calculating the formal charge on an atom in a Lewis structure?

Accepted Answer

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

Question 9

Which of the following molecules is an example of a resonance structure?

Accepted Answer

$$\mathrm{O_3$}$$

Question 10

Which of the following is NOT a property of ionic compounds?

Accepted Answer

Low melting points

Question 11

Which of the following elements can have an expanded octet in its Lewis structure?

Accepted Answer

Phosphorus

Question 12

A molecule has the following Lewis structure: $$\mathrm{N \equiv N}. $$What type of bond is present between the two nitrogen atoms?

Accepted Answer

Triple bond

Question 13

Which of the following best describes the electron configuration of a chloride ion, $$\mathrm{Cl^-}$$?

Accepted Answer

Same as argon

Question 14

Which of the following is a correct statement about resonance structures?

Accepted Answer

Resonance structures are used when one Lewis structure cannot accurately depict the molecule.

Question 15

Which of the following molecules is an example of a molecule with an odd number of electrons?

Accepted Answer

$$\mathrm{NO}$$

Question 16

Which of the following best explains why metals tend to form cations?

Accepted Answer

Metals have low ionization energies and readily lose electrons to achieve a noble gas configuration.

Question 17

Which of the following is the best method to determine whether a compound is ionic or covalent?

Accepted Answer

Measure the melting point; lower melting points usually indicate covalent bonding.

Question 18

Which of the following is true about the electron configuration of transition metal ions?

Accepted Answer

Transition metals lose their valence electrons first, then lose d-electrons as needed for the ion charge.

Question 19

Which of the following is a correct statement about the octet rule?

Accepted Answer

Some elements, such as boron, can be stable with fewer than eight electrons.

Basic Concepts of Chemical Bonding: Ionic and Covalent Bonds, Lewis Structures, and Exceptions to the Octet Rule

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