What is the name of the following ion: H 2PO4-?
For this problem, we are asked to name the ion H2PO4-.
First, we need to determine whether it is an ionic compound, covalent compound or an acid (binary or oxyacid). Based on its chemical formula, H2PO4- is similar to an oxyacid
**H+ ion bonded to PO4 which is a polyatomic anion containing O.
An oxyacid is a covalent compound that contains an H+ ion connected to a polyatomic ion containing oxygen.
Recall that the rules for naming ions are similar to naming oxyacids in gas phase (not aqueous):
1. Start with Hydrogen, write a prefix to indicate the number of H, (except for mono)
The numerical prefixes are:
Mono – 1 Di – 2
Tri – 3 Tetra – 4
Penta – 5 Hexa – 6
Hepta – 7 Octa – 8
Nona – 9 Deca – 10
2. For Polyatomic ions they retain their name
**no prefixes needed
**no need to change ending to -ide