Question

Which of the following statements are true regarding a covalent bond between carbon and oxygen atoms in a carbon monoxide, \(\mathrm{CO},\) molecule? (a) Valence electrons are transferred from carbon to oxygen atoms. (b) Bonding electrons are distributed over the entire \(\mathrm{CO}\) molecule. (c) The bond length is less than the sum of the two atomic radii. (d) Energy is released when a covalent bond is broken.

Short answer

Statement (c) is true; the bond length is less than the sum of the two atomic radii.

Step-by-step solution

Understand Covalent Bonding

A covalent bond involves the sharing of valence electrons between two atoms. In a carbon monoxide molecule, which consists of a carbon atom and an oxygen atom, electrons are shared rather than transferred. Therefore, statement (a), which suggests that valence electrons are transferred, is incorrect.

Analyze Electron Distribution

In a covalent compound like CO, the shared electrons form electron clouds that extend between the bonded atoms, thus being concentrated around the CO bond rather than distributed over the entire molecule. Therefore, statement (b) is misleading and incorrect for a simple CO molecule.

Evaluate Bond Length

In a molecule like CO, covalent bonds shorten the distance between the atoms compared to their individual atomic radii. A triple bond in CO means strong attraction and short bond length, which indeed is less than the sum of the atomic radii of carbon and oxygen. Therefore, statement (c) is true.

Consider Energy and Bond Breaking

When a covalent bond forms, energy is released. In contrast, breaking a covalent bond requires the input of energy, not the release. As such, statement (d) is incorrect, as breaking the bond would not release energy but consume it.

Key concepts

Valence Electrons

Understanding valence electrons is key to mastering covalent bonding. Valence electrons are the electrons present in the outermost electron shell of an atom. They are crucial because they determine how the atom can interact chemically with other atoms. In covalent bonds, like those in a carbon monoxide (CO) molecule, valence electrons from carbon and oxygen are shared between the atoms.

This sharing results in a stable electron configuration for both atoms involved in the bond. Unlike ionic bonds, where electrons are transferred from one atom to another, covalent bonds rely on the sharing of these electrons.

• Each atom aims to reach a stable configuration, particularly resembling that of the noble gases.
• Carbon and oxygen share these valence electrons to form the strong triple bond in CO.

The sharing of valence electrons rather than their transfer distinguishes covalent bonds from other types of chemical bonds.

Electron Distribution

Electron distribution in a molecule shows how electrons are spread across atoms and bonds. In simple covalent compounds like carbon monoxide, electron distribution is concentrated around the covalent bond formed between the two atoms. This concentration forms a region called an electron cloud or bonding electron cloud.

The high electron density around the bond in CO indicates that the electrons are not freely dispersed over the entire molecule. Instead:

• Electrons create a strong localized region between carbon and oxygen.
• This leads to stronger and more stable covalent bonds.

By understanding this distribution, we comprehend why the electrons predominantly inhabit the area between the bonded atoms, fostering stronger atomic connections.

Bond Length

The concept of bond length is pivotal in understanding molecular structure. Bond length refers to the distance between the nuclei of two bonded atoms. In covalent bonds, like the bond between carbon and oxygen in CO, the length is shorter than the sum of their atomic radii.

A triple bond, as found in CO, involves significant sharing of electrons, leading to a very strong and correspondingly short bond length.

• This reduced bond length enhances the stability and strength of the molecule.
• The strong attraction between shared electrons and the bonded nuclei is responsible for the shortened distance.

Understanding bond length helps predict molecular behavior and reactivity, especially when evaluating molecular stability and strength.

Energy in Bond Breaking

Energy considerations are essential when discussing covalent bonds. A fundamental aspect is the energy required to break these bonds. When molecules form, energy is released as the atoms bond and stabilize. Conversely, breaking a covalent bond, such as in CO, requires an input of energy rather than releasing it.

This requirement for energy input implies:

• Covalent bonds hold substantial energy due to their stability and strength.
• The energy provided equates with breaking the bond against the electrostatic forces keeping atoms together.

Thus, understanding energy changes during bond formation and breaking allows us to predict a molecule's behavior in chemical reactions and how it interacts within different environments.