Which of the following compounds does not contain a polyatomic ion? How do you determine this?

calcium carbonate
calcium sulfate
calcium phosphate
calcium sulfide?

1 Answer
Jun 3, 2018

Answer:

Calcium Sulfide: #"CaS"#

Explanation:

A polyatomic ion is an ion with multiple atoms.

Polyatomic ions examples:

  • sulfate: #"SO"_4^(2-)#
  • phosphite: #"PO"_3^(3-)#
  • ammonium: #"NH"_4^+#

Monoatomic ions examples:

  • chloride: #"Cl"^-#
  • iron(III): #"Fe"^(3+)#
  • oxide: #"O"^(2-)#

Most monoatomic anions end with -ide, such as oxide and fluoride. Calcium #("Ca")# sulfide #("S")# would follow that rule.