What would the respective names for the polyatomic ions of phosphorous, PO4 and PO3, be?
A phosphate and phosphite
B phosphate and phosphide
The Correct Answer and Explanation is :
The correct answer is A. phosphate and phosphite.
Explanation:
In chemistry, polyatomic ions are ions that consist of two or more atoms covalently bonded, carrying a net charge. For phosphorus-based polyatomic ions, the naming convention changes based on the number of oxygen atoms attached to the phosphorus atom.
- Phosphate (PO₄³⁻):
- “Phosphate” is the name for the polyatomic ion with the formula ( \text{PO}_4^{3-} ).
- It has four oxygen atoms bonded to a single phosphorus atom and carries a -3 charge.
- The “-ate” suffix is commonly used in naming the most common or typical oxyanion of an element that contains oxygen. In this case, phosphate is the standard oxyanion for phosphorus.
- Phosphite (PO₃³⁻):
- “Phosphite” refers to the polyatomic ion with the formula ( \text{PO}_3^{3-} ).
- This ion has three oxygen atoms bonded to phosphorus, also carrying a -3 charge.
- The “-ite” suffix indicates one fewer oxygen atom than the “-ate” form. Phosphite has one less oxygen atom than phosphate but retains the same -3 charge.
This pattern of naming extends to other elements with polyatomic ions that form oxyanions with different numbers of oxygen atoms. The suffix “-ate” is used for the oxyanion with a relatively higher number of oxygen atoms, while “-ite” is used for the one with fewer oxygen atoms.
Common Mistake:
Some might confuse the terms with “phosphide,” which refers to a different kind of ion. A phosphide ion has the formula ( \text{P}^{3-} ), containing only phosphorus without any oxygen atoms, and is therefore not a polyatomic ion like phosphate or phosphite.