High School Chemistry : Help with Covalent Bonds

Study concepts, example questions & explanations for High School Chemistry

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Example Questions

Example Question #1 : Help With Covalent Bonds

Which compound has both ionic and covalent bonds?

Possible Answers:

Correct answer:

Explanation:

In , the nitrogen is bound covalently to the three oxygens, and the complex has an overall of .

Sodium has a charge of , and is ionically bound to the  complex.

When put into water, the compound will dissociate into  and .

HCl is an ionic compound, while the other answer choices have only covalent bonds.

Example Question #2 : Help With Covalent Bonds

Which of the following is not true of covalent bonds?

Possible Answers:

The bond can be polar or nonpolar

The elements in the bond have a large difference in electronegativity

The bond can involve halogens

Covalent bonds readily form between two non-metals

The atoms in the bond have high electronegativities

Correct answer:

The elements in the bond have a large difference in electronegativity

Explanation:

Covalent bonds form when two atoms share electrons, caused by an overlap of their orbitals. Each atom has a similar amount of "pull" on the electrons, preventing them from getting too close to one atom or the other and keeping them in the middle. This "pull" is the electronegativity. Atoms in covalent bonds have similar electronegativity values to keep the electrons in the center. When the electronegativities are slightly different, the electrons can lean toward one atom. The result is a polar bond, in which one atom is closer to the electrons (negative) and the other is farther (positive). Most non-metals have very high and very similar electronegativity values, and will readily form covalent bonds.

When the difference in electronegativity, or "pull," is too great, the electrons will be transferred from one atom to the other. The result is an ionic bond, which usually forms between a metal (low electronegativity) and a non-metal (high electronegativity).

Example Question #41 : Compounds And Bonding

Which of the following describes a covalent bond?

Possible Answers:

Two or more electrons are shared between two atoms

An electron is shared between two atoms

An electron is donated from one atom to another

A proton is shared between two atoms

A proton is donated from one atom to another

Correct answer:

Two or more electrons are shared between two atoms

Explanation:

There are two primary types of intramolecular bonds: ionic bonds and covalent bonds. In an ionic bond, an electron is transferred (donated) from one atom to the other, usually allowing both atoms to satisfy the octet rule. In a covalent bond, electrons are shared between two atoms in order to allow both to satisfy the octet rule. A covalent single bond consists of two shared electrons, while a double bond will consist of four and a triple bond will consist of six.

Covalent bonds usually form between two non-metals. Diatomic gases, CH4, and NaOH are all examples of molecules that contain covalent bonds.

Example Question #42 : Compounds And Bonding

What is the term for a covalent bond in which electrons are not shared equally?

Possible Answers:

Polar covalent bond

Coordinate covalent bond

Double bond

Ionic bond

Non-polar covalent bond

Correct answer:

Polar covalent bond

Explanation:

A polar covalent bond describes a bond between two atoms that share electrons unequally. This results from a difference in electronegativity between the atoms. This difference is enough to cause a dipole, but not enough to consitute an ionic bond.

A non-polar covalent bond is a bond between two atoms sharing ions equally due to similar electronegativities.

A double bond occurs when four electrons are shared between two atoms.

A coordinate covalent bond refers to a covalent bond in which one atom donates both shared electrons.

Example Question #43 : Compounds And Bonding

Pauling electronegativity values:

 

Based on the given electronegativities, which of these bonds would most likely be a nonpolar covalent bond?

Possible Answers:

 only

 only

Correct answer:

Explanation:

A nonpolar covalent bond occurs when two atoms share electrons equally. This happens when the electronegativities of each atom is relatively close to one another. For example, in water, oxygen is much more electronegative than hydrogen (3.5 and 2.1 respectively), oxygen keeps the electrons closer to its nucleus and results in uneven sharing of the electrons between itself and the two hydrogen atoms. This results in a net dipole in the molecule with the oxygen-end being slightly negative, and the hydrogen-end being slightly positive.

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