Physical Chemistry : Covalent Bonding

Study concepts, example questions & explanations for Physical Chemistry

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Example Questions

Example Question #1 : Covalent Bonding

Which statement best characterizes a covalent bond? 

Possible Answers:

Electrical conduction

Crystal structure

Electron sea

Cations and anions

Sharing electrons between atoms 

Correct answer:

Sharing electrons between atoms 

Explanation:

To achieve an octet of valence electrons, atoms can share electrons so that all atoms participating in the bond will have full valence shells. Covalent bonds, by definition, result from the sharing of one or more pairs of valence electrons.

Example Question #2 : Covalent Bonding

How many single covalent bonds would the element sulfur be expected to form in order to obey the octet rule?

Possible Answers:

Correct answer:

Explanation:

The key to this problem is that electrons in covalent bonds are shared and therefore "belong" to both of the bonded atoms. Sulfur is a nonmetal in group 6A , and therefore has 6 valence electrons. In order to obey the octet rule, it needs to gain 2 electrons . It can do this by forming 2 single covalent bonds.

Example Question #3 : Covalent Bonding

How many single covalent bonds would the element selenium be expected to form in order to obey the octet rule? 

Possible Answers:

0

Correct answer:

Explanation:

The key to this problem is that electrons in covalent bonds are shared and therefore "belong" to both of the bonded atoms. Selenium is a nonmetal in group 6A , and therefore has 6 valence electrons. In order to obey the octet rule, it needs to gain 2 electrons. It can do this by forming 2 single covalent bonds.

Example Question #4 : Covalent Bonding

Which of the following constitutes a covalent bond?

Possible Answers:

Electron pair shared between two neighboring atoms

Constructive interference between atomic orbitals

All of these

Atoms of similar electronegativities

Spin pairing of electrons

Correct answer:

All of these

Explanation:

A chemical bond is considered covalent if there is sharing of one or more pairs of electrons between atoms. As opposed to a covalent bond, an ionic bond can involve the transfer of electrons from one atom to another resulting in a high charge differential between two atoms in order for them to acquire a full octet.

As described by the Pauli Exclusion Principle, every pair of electrons must consist of spin-up paired with spin-down. It states that no more than two electrons may occupy an orbital, and in full electron orbitals, the spin of one must cancel the spin of the other so their spins will have a zero net spin/angular momentum.

Chemical bonds are made up of orbitals, which are simply waves that have wave functions. Wave functions tell us the likelihood that an electron can be found within an orbital. Constructive interference of two wave functions/orbitals occur when the two waves are in phase and result in a new wave function, or in other words a chemical bond.

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