AP Chemistry : Covalent Bonds

Study concepts, example questions & explanations for AP Chemistry

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Example Questions

Example Question #1 : Covalent Bonds

What is the character of the bonds in a molecule of ammonium?

Possible Answers:

4 polar covalent bonds

3 polar covalent bonds

2 polar covalent bonds, 2 ionic bonds

3 polar covalent bonds, one coordinate covalent bond

Correct answer:

3 polar covalent bonds, one coordinate covalent bond

Explanation:

Ammonium is NH4+. It is formed by the association of NH3 with H+. Thus, NH3 acts as a Lewis base, and H+ is a Lewis acid. This is a coordinate covalent bond, and there is one of these in the molecule. The remaning three bonds are polar covalent (N–H bonds).

Example Question #2 : Covalent Bonds

What type of compound is ?

Possible Answers:

Metallic

Polyatomic ion

Ionic

Covalent

Correct answer:

Covalent

Explanation:

Covalent compounds generally form between two nonmetals that will both share electrons to complete their octets. Boron (B) is a metalloid and can act as a metal or nonmetal. In its bonds with fluorine (F), however, the two compounds have relatively similar electronegativities. A lack of difference in electronegativity results in covalent bonds.

Ionic compounds form between metals and nonmetals through a transfer of electrons, Metallic compounds are built from only metals. Polyatomic ions will have a formal charge.

Example Question #3 : Covalent Bonds

What property determines the polarity of a covalent bond?

Possible Answers:

The atomic radii of the atoms involved

The molecular geometry

The electronic geometry of the compound

The electronegativities of the atoms involved

Correct answer:

The electronegativities of the atoms involved

Explanation:

Polarity in a bond results from an uneven sharing of electrons. An extreme example is an ionic bond, in which an electron is almost fully transferred from one atom to another due to the second atom's electron affinity.

In order to generate an uneven pull on shared electrons, the atoms involved in the bond must have significantly differing electronegativities. This will cause one atom to pull electrons closer to its nucleus, away from the other atom involved.

Molecular and electronic geometry can affect the polarity of a compound, but do not directly affect polarity of a single given bond. Atomic radius does not play a significant role in polarity.

Example Question #3 : Covalent Bonds

What types of bonds are present in the molecule ?

Possible Answers:

Ionic and covalent bonds

Single covalent bonds

Double covalent bonds

Single and double covalent bonds

Correct answer:

Single and double covalent bonds

Explanation:

In carbon has a single bond to each hydrogen and a double bond to oxygen. Carbon must form four bonds to satisfy the octet rule. Only single bonds can be formed with hydrogen, but oxygen can form double bonds. The carbon will thus form two single bonds and one double bond.

Example Question #94 : Ap Chemistry

What is the type of bond in which both electrons being shared are contributed by only one of the two atoms?

Possible Answers:

Coordinate covalent

Nonpolar

Covalent

Ionic

Correct answer:

Coordinate covalent

Explanation:

The definition of a coordinate covalent bond is that one of the atoms donates both of the electrons being shared. This corresponds with the correct answer choice.

Example Question #4 : Covalent Bonds

What type of bond is present between the atoms of carbon dioxide?

Possible Answers:

Polar covalent

Nonpolar covalent

Coordinate covalent

Ionic

Correct answer:

Polar covalent

Explanation:

Carbon dioxide has a double bond between the carbon and oxygen molecules. Since there is a moderately large electronegativitiy difference between C and O, the bond can be described as polar covalent.

Though the bonds themselves are polar, the overall symmetry of the molecule means that carbon dioxide has a net zero dipole and is a nonpolar compound.

Example Question #5 : Covalent Bonds

Which of the following describe a covalent bond?

Possible Answers:

The metal accepts an electron

None of these

The nonmetal gives up an electron

Both metals give up an electron

Electrons are being shared

Correct answer:

Electrons are being shared

Explanation:

In a covalent bond, electrons are shared between two nonmetals. If there is a metal in the compound, that is called an ionic compound, not a covalent compound. Ionic bonds involve the complete transfer of an electron from one species to another.

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