It is convenient to classify substances as ionic or covalent. How would you classify sodium sulfate? Explain fully.
The correct answer and explanation is:
Correct Answer: Sodium sulfate (Na₂SO₄) is classified as an ionic compound that contains covalent bonds.
Explanation (Approx. 300 Words):
To understand how sodium sulfate is classified, we need to examine the nature of the bonds in the compound.
1. What is Sodium Sulfate?
Sodium sulfate is a chemical compound with the formula Na₂SO₄. It consists of two sodium ions (Na⁺) and one sulfate ion (SO₄²⁻).
2. Ionic Bonding in Sodium Sulfate
The bond between the sodium ions (Na⁺) and the sulfate ion (SO₄²⁻) is ionic. This is because sodium is a metal, and sulfate is a polyatomic ion with an overall negative charge. Metals like sodium tend to lose electrons and form cations, while nonmetals or polyatomic ions tend to gain electrons or already have a negative charge.
When sodium ions and sulfate ions come together, they form an electrostatic attraction—the defining feature of ionic bonds. Therefore, the overall structure of Na₂SO₄ is ionic.
3. Covalent Bonding within the Sulfate Ion
Inside the sulfate ion (SO₄²⁻), the sulfur atom is covalently bonded to four oxygen atoms. These bonds involve the sharing of electrons, which is characteristic of covalent bonds. The sulfur and oxygen atoms are both nonmetals, and they form polar covalent bonds due to a difference in electronegativity.
4. Final Classification
Thus, sodium sulfate is best described as a compound with ionic bonding between ions (Na⁺ and SO₄²⁻) and covalent bonding within the polyatomic ion (SO₄²⁻). It is not purely ionic or covalent, but a combination of both types of bonding.
Summary:
Sodium sulfate is an ionic compound overall, but it contains covalent bonds within the sulfate ion. This dual nature is common in salts containing polyatomic ions.