Question

Determine whether each of the following has the same number of bonding electrons as the cyanide ion, \(\mathrm{CN}^{-}\). (a) \(\mathrm{O}_{2}\) (c) \(\mathrm{CO}\) (e) \(\mathrm{NH}_{3}\) (b) \(\mathrm{NO}^{+}\) (d) \(\mathrm{N}_{2}\)

Short answer

Among the given compounds, only CO and N2 have the same number of bonding electrons as the cyanide ion, CN-.

Step-by-step solution

Identify the Cyanide Ion bonding electrons

Calculate the number of bonding electrons for \(\mathrm{CN}^{-}\). There is a triple bond between C and N. Each bond consists of 2 bonding electrons, so in total there are six bonding electrons.

Compare with \(\mathrm{O}_{2}\)

Calculate the number of bonding electrons for \(\mathrm{O}_{2}\). It has a double bond and one lone pair for each O, so it has four bonding electrons.

Compare with \(\mathrm{CO}\)

Calculate the number of bonding electrons for \(\mathrm{CO}\). It has a triple bond, giving six bonding electrons.

Compare with \(\mathrm{NH}_{3}\)

Calculate the number of bonding electrons for \(\mathrm{NH}_{3}\). NH3 has three single bonds, so it has three bonding electrons.

Compare with \(\mathrm{NO}^{+}\)

Calculate the number of bonding electrons for \(\mathrm{NO}^{+}\). NO+ ion has a double bond, representing four bonding electrons.

Compare with \(\mathrm{N}_{2}\)

Calculate the number of bonding electrons for \(\mathrm{N}_{2}\). N2 has a triple bond so there are six bonding electrons.

Key concepts

Exploring the Triple Bond

A triple bond is a type of chemical bond where three pairs of electrons are shared between two atoms. It is one of the strongest types of bonds because it involves the sharing of more electrons between atoms, which increases the bond strength.
In the context of the cyanide ion, \(\text{CN}^{-}\), it consists of a carbon (C) and nitrogen (N) atom, joined by a triple bond. This results in six bonding electrons since each bond contains two electrons.

Triple bonds are often found in diatomic molecules like nitrogen (_2) and other linear molecules. In addition to holding atoms tightly together, triple bonds also affect the molecule's geometry, usually resulting in a linear arrangement between the two bonded atoms.

• Characteristics of Triple Bonds: Increase in bond strength
• Linear molecular shape
• Presence in molecules like \(\text{N}_2\) and compounds like \(\text{CN}^-\)

Understanding triple bonds in molecules is crucial for comprehending their reactivity and properties.

Understanding the Double Bond

A double bond involves the sharing of two pairs of electrons between two atoms. It's a common type of chemical bond and is part of many organic and inorganic compounds.
Double bonds are generally portrayed using two parallel lines between the bonded atoms. Each double bond contributes four electrons to the bonding process, resulting in a moderate level of bond strength when compared to single and triple bonds.
In the exercise, molecules like \(\text{O}_{2}\) and \(\text{NO}^{+}\) showcase examples of double bonds.

• For \(\text{O}_2\), the double bond links two oxygen atoms together, establishing a bond with four bonding electrons.
• Similarly, the \(\text{NO}^+\) ion carries a double bond that denotes the sharing of four bonding electrons between nitrogen and oxygen atoms.
• Characteristics: Moderate bond strength
• Frequently found in unsaturated hydrocarbons like alkenes

Double bonds impart specific properties to the molecules, such as limited rotational freedom compared to single bonds, which impacts the physical behavior and reactions of the molecules they are part of.

Key Chemical Bonding Concepts

Chemical bonding is a vital concept in chemistry that describes how atoms connect to form molecules. Bonds are categorized primarily into three types based on how electrons are shared or transferred among atoms: single, double, and triple bonds.
Single bonds share one pair of electrons and are generally the weakest type and longest in bond length. Double bonds share two pairs of electrons, offering a balance of strength and flexibility with a medium bond length.
Triple bonds, such as those in \(\text{CN}^-\), involve sharing three pairs of electrons, resulting in the shortest and strongest bond in terms of bond length and energy.

• Types of Bonds: Single, double, and triple
• Single bond: one electron pair
• Double bond: two electron pairs
• Triple bond: three electron pairs

Understanding these bonds helps in predicting molecular geometry, reactivity, and the physical properties of compounds.
Knowing how atoms bond and interact is crucial for studying everything from simple molecules to complex biological systems and materials science.