Problem 129 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following types of bonds are present in \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O} ?\) (1) electrovalent (2) covalent (3) coordinate Select the correct answer using the code given below. (a) 1 and 2 only (b) 1 and 3 only (c) 1,2 and 3 (d) 2 and 3 only

Step-by-Step Solution

Answer

(c) 1, 2 and 3

Step 1: Identify the Compound Components

The compound \( \mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O} \) is composed of copper sulfate \( \mathrm{CuSO}_{4} \) and water molecules \( 5 \mathrm{H}_{2} \mathrm{O} \). Copper sulfate consists of copper (Cu), sulfur (S), and oxygen (O) atoms.

Step 2: Analyze Electrovalent (Ionic) Bonds

Electrovalent, or ionic, bonds occur when electrons are transferred between atoms, leading to positive and negative ions. In \( \mathrm{CuSO}_{4} \), copper (Cu) carries a +2 charge and sulfate (SO₄) has a -2 charge, forming iconic bonds due to the electrostatic attraction between them.

Step 3: Examine Covalent Bonds

Covalent bonds involve sharing of electrons between atoms. In the sulfate ion (SO₄²⁻), sulfur and oxygen atoms share electrons forming covalent bonds. Additionally, the water molecules \( \mathrm{H}_{2} \mathrm{O} \) in the compound also feature covalent bonds between the hydrogen and oxygen atoms.

Step 4: Consider Coordinate Bonds

Coordinate bonds (or dative bonds) occur when a lone pair of electrons from one atom is shared with another atom. In \( \mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O} \), the water molecules can act as ligands, donating lone pairs of electrons to the copper ion, thereby forming coordinate bonds.

Key Concepts

Electrovalent Bond

An electrovalent bond, also known as an ionic bond, is a type of chemical bonding where electrons are transferred between atoms. This transfer typically happens between metals and non-metals, leading to the formation of ions—atoms or molecules with positive or negative charges.

• In an electrovalent bond, one atom loses electrons to become a positively charged ion, while another atom gains those electrons to become a negatively charged ion.
• These oppositely charged ions attract each other, forming a firm ionic bond through electrostatic forces.

In the compound \( \mathrm{CuSO}_{4} \), copper (Cu) forms an electrovalent bond with the sulfate ion \( \mathrm{SO}_4^{2-} \). Copper, a metal, loses two electrons to become \( \mathrm{Cu}^{2+} \), while the sulfate group, a non-metal, accepts these electrons to balance its charge. This results in a solid ionic compound due to the strong attraction between \( \mathrm{Cu}^{2+} \) and \( \mathrm{SO}_4^{2-} \).

Covalent Bond

Covalent bonds involve the sharing of electron pairs between atoms, allowing each atom to achieve a full outer electron shell, resulting in a more stable molecule. Covalent bonding typically occurs between non-metal atoms.

• Electrons are shared because the atoms involved have similar electronegativities, meaning neither atom is strong enough to completely remove electrons from the other.
• These bonds can be single, double, or triple, depending on the number of shared electron pairs.

Within \( \mathrm{CuSO}_{4} \), the sulfate ion \( \mathrm{SO}_4^{2-} \) is bonded covalently as sulfur shares electrons with oxygen atoms. Similarly, in the water molecules \( \mathrm{H}_2\mathrm{O} \), there are covalent bonds between the oxygen and hydrogen atoms. This sharing of electrons forms a stable configuration for all the atoms involved.

Coordinate Bond

A coordinate bond, also known as a dative covalent bond, occurs when both electrons in the shared pair come from the same atom. This type of bonding is crucial in the formation of complex structures, especially in coordination chemistry.

• Coordinate bonds are often found between metal ions and ligands, where the ligand donates a pair of electrons to the metal atom.
• These bonds are typically less strong than ionic bonds but are crucial for the stability of many compounds.

In \( \mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O} \), water molecules act as ligands, providing lone pairs of electrons to the copper ion. This interaction results in the formation of coordination complexes, where the water molecules effectively "coordinate" with the copper ion, stabilizing the entire structure through coordinate bonding.