Give the name for the polyatomic ion shown. Careful with spelling. SO3
The Correct Answer and Explanation is:
The name of the polyatomic ion SO₃²⁻ is sulfite.
Explanation
The chemical formula SO₃²⁻ represents a polyatomic ion consisting of one sulfur (S) atom and three oxygen (O) atoms, carrying an overall charge of -2. This ion is called sulfite.
To understand the naming, it’s helpful to look at how polyatomic ions are typically named based on the number of oxygen atoms in relation to a central atom, often a nonmetal like sulfur. In this family of oxyanions (ions that contain oxygen), suffixes like -ite and -ate are used to distinguish between ions with different numbers of oxygen atoms.
- Sulfate is SO₄²⁻, which contains one more oxygen atom than sulfite.
- Sulfite, SO₃²⁻, has one fewer oxygen atom than sulfate.
The naming rule is that when there are two common oxyanions of an element:
- The one with more oxygen atoms gets the suffix -ate (sulfate for SO₄²⁻).
- The one with fewer oxygen atoms gets the suffix -ite (sulfite for SO₃²⁻).
So, because SO₃²⁻ has one less oxygen than SO₄²⁻, it is called sulfite.
The charge on the sulfite ion is -2, which means it has two more electrons than protons. These extra electrons are distributed over the ion and contribute to its chemical properties and bonding behavior. The geometry of the sulfite ion is trigonal pyramidal, due to the presence of a lone pair on the sulfur atom, which affects the overall shape.
Sulfite ions are often found in preservatives and are known for their ability to prevent oxidation. They are commonly used in the food and beverage industry, particularly in wines and dried fruits. However, some individuals may have allergic reactions or sensitivities to sulfites.
To summarize, SO₃²⁻ is the sulfite ion, named based on its oxygen content relative to similar ions in the same group.
