Learning the common polyatomic ions is a right of passage for all chemistry classes. The good news, is that many of these ions are really cool, reactive, and or colorful. So let’s jump right in and look at the list of common polyatomic ions. Afterwards, we’ll share some cool facts about these ions, and talk about some not-so common ones. If you haven’t yet, review our article on cations and anions.
Covered in other articles:
Most Common Polyatomic Ions
Bicarbonate HCO3– (Hydrogen Carbonate)
Hydrogen Sulfate HSO4– (Bisulfate)
Less Common Polyatomic Ions
Borate BO4-3 (Orthoborate)
Dihydrogen Phosphate H2PO4–
Monohydrogen Phosphate HPO4-2
Hydrogen Sulfite HSO3– (Bisulfite)
Mercury (I) Hg2+2 (Mercurous)
Polyatomic Ions – fun facts
- Thiocyanate ion is used as a sensitive test for Fe+3
- There are many different silicate ions, with different quantities of Si and O
- Chlorates and Perchlorates are often used in explosives
- Dichromates are often colored a brilliant yellow
- The mercury (I) ion, while still toxic, is less so than mercury (II)
- Ants use the formate ion as a weapon, in the form of formic acid
- Nitrate salts are universally soluble (inorganic ones; oxynitrates not included)
- Thiosulfate ion has a great use – cleaning iodine stains
- Some metal oxalates decompose when heated to form a pyrophoric elemental powder. Cool!
- The silicate ion can be used to form a chemical garden when colorful metal salts are added to the solution
- Sodium dihydrogen phosphate is also called monosodium phosphate. Yeah, confusing.
- Ferric ferrocyanide is used as an emergency cure for thallium poisoning