Question

In a coordinate covalent bond, the shared electrons are furnished by only one species. Which of the following molecules is L.EAST likely to be involved in a coordinate covalent bond? A. sodium chloride \((\mathrm{NaCl})\) B. chlorate ion \(\left(\mathrm{ClO}_3\right)\) C. ammonia \(\left(\mathrm{NH}_3\right)\) D. Water \(\left(\mathrm{H}_2 \mathrm{O}\right)\)

Short answer

A. Sodium chloride \( \text{NaCl} \)

Step-by-step solution

- Understand Coordinate Covalent Bonds

A coordinate covalent bond, also known as a dative bond, occurs when a pair of electrons is shared between two atoms, with both electrons being furnished by one atom. Typically, look for species with lone pairs of electrons.

- Analyze Each Option

Evaluate each option to see if it has lone pairs of electrons to donate for a coordinate covalent bond: A. Sodium chloride \(\text{NaCl}\) is an ionic compound and doesn't form coordinate covalent bonds. B. Chlorate ion \( \text{ClO}_3^{-} \) has lone pairs on oxygen and chlorine. C. Ammonia \( \text{NH}_3 \) has one lone pair on nitrogen. D. Water \( \text{H}_2 \text{O} \) has two lone pairs on oxygen.

- Eliminate Options Involving Coordinate Covalent Bonds

Since coordinate covalent bonds require available lone pairs, eliminate B, C, and D as they all contain lone pairs which can form such bonds.

- Identify the Least Likely Molecule

The only remaining option is sodium chloride (A), which is an ionic compound and does not have lone pairs to donate for forming coordinate covalent bonds.

Key concepts

Lone Pairs

Lone pairs are pairs of valence electrons that are not shared with another atom in a molecule. They are also known as non-bonding pairs. These electrons belong exclusively to one atom. The presence of lone pairs can affect the shape of a molecule and its ability to form bonds, including coordinate covalent bonds.
Lone pairs are important in the formation of coordinate covalent bonds, where both electrons in the bond come from the same atom.
Some common examples of molecules with lone pairs include:

• Ammonia \(\text{NH}_3\), which has one lone pair on nitrogen.
• Water \(\text{H}_2\text{O}\), which has two lone pairs on oxygen.
• Chlorate ion \(\text{ClO}_3^-\), which has lone pairs on both chlorine and oxygen.

Understanding where lone pairs are in a molecule helps predict where coordinate covalent bonds can form.

Ionic Compound

Ionic compounds are made up of positively charged ions (cations) and negatively charged ions (anions). These ions are held together by strong electrostatic forces, known as ionic bonds. Unlike covalent bonds that involve sharing electrons, ionic bonds form when one atom donates an electron to another atom.
Sodium chloride (\(\text{NaCl}\)) is an example of an ionic compound. In \(\text{NaCl}\), the sodium ion (\(\text{Na}^+\)) gives away an electron to the chlorine ion (\(\text{Cl}^-\)), resulting in a stable ionic structure.
Ionic compounds do not form coordinate covalent bonds because they do not share electrons in the same way covalent compounds do. This makes \(\text{NaCl}\) least likely to engage in coordinate covalent bonding compared to molecules with lone pairs of electrons.

Dative Bond

A dative bond, or coordinate covalent bond, is a type of covalent bond where both of the shared electrons come from the same atom. This usually occurs between a molecule with a lone pair of electrons and a molecule that can accept those electrons, often a positively charged ion or an electron-deficient atom.
For example, in the formation of the ammonium ion (\(\text{NH}_4^+\)), ammonia (\(\text{NH}_3\)) uses its lone pair on nitrogen to form a dative bond with a proton (\(\text{H}^+\)). The result is a stable structure with a coordinate covalent bond.
Here are some features of dative bonds:

• Both electrons in the bond originate from the same atom.
• The resulting bond is often identical in strength and length to regular covalent bonds.
• Commonly found in coordination compounds, where a central metal ion binds to molecules with lone pairs.

Understanding dative bonds is key to grasping how certain complex molecules and ions come together.