Symbols and Names for Common Polyatomic Ions

Symbols and Names of Some Common Polyatomic Ions and One Molecule
NH₄⁺	ammonium ion	OH^-	hydroxide ion	CN^-	cyanide ion
SO₄^2-	sulfate ion	O₂^2-	peroxide ion	CNO^-	cyanate ion
HSO₄^-	hydrogen sulfate ion	C₂H₃O₂^-	acetate ion	SCN^-	thiocyanate ion
SO₃^2-	sulfite ion	ClO₄^-	perchlorate ion	CO₃^2-	carbonate ion
NO₃^-	nitrate ion	ClO₃^-	chlorate ion	HCO₃^-	hydrogen carbonate
NO₂^-	nitrite ion	ClO₂^-	chlorite ion	C₂O₄^2-	oxalate ion
PO₄^3-	phosphate ion	ClO^-	hypochlorite ion	S₂O₃^2-	thiosulfate ion
HPO₄^2-	hydrogen phosphate	CrO₄^2-	chromate ion	Hg₂²⁺	mercury(I) ion
H₂PO₄^-	dihydrogen phosphate	Cr₂O₇^2-	dichromate ion	H₃O⁺	hydronium ion
PO₃^3-	phosphite ion	MnO₄^-	permanganate ion	NH₃	ammonia
*Formulas and Names for Some Common Acids (all names should have acid added)*
H₂SO₄	sulfuric	H₃PO₄	phosphoric	HNO₃	nitric
HC₂H₃O₂	acetic	HCl	hydrochloric	HBr	hydrobromic
HClO₃	chloric	HClO₂	chlorous	HBrO₃	bromic

Oxidation States For Metals (Cations) and Non-metals (Anions) In Compounds
Group Oxidation States for Metal Cations Group Oxidation States for Non-metal Anions

IA Always +1 (Li, Na, K, Rb, Cs, Fr) IVA Always -4 (C^4-) as an anion

IIA Always +2 (Be, Mg, Ca, Sr, Ba, Ra) VA Always -3 (N^3-, P^3-) as an anion

IIIB Always +3 (Sc, Y, La) VIA Always -2 (O^2-, S^2-, Se^2-, Te^2-) as an anion

IVB-
VIIIB Commonly +2 and +3 (e.g., Cr, Mn, Fe, Co, Ni) VIIA Always -1 (F^-, Cl^-, Br^-, I^-) as an anion

IB Cu (+1, +2); Ag (+1); Au (+1, +3) hydrogen Always -1 (H^-) as anion; but +1 otherwise

IIB Zn and Cd (+2); Hg (+1, +2)

IIIA Al and Ga (+3); In and Tl (+1, +3)

IVA Sn and Pb (+2, +4)

VA Bi (+3, +5)

**Oxidation States For Metals (Cations) and Non-metals (Anions) In Compounds**
Group	Oxidation States for Metal Cations	Group	Oxidation States for Non-metal Anions
IA	Always +1 (Li, Na, K, Rb, Cs, Fr)	IVA	Always -4 (C^4-) as an anion
IIA	Always +2 (Be, Mg, Ca, Sr, Ba, Ra)	VA	Always -3 (N^3-, P^3-) as an anion
IIIB	Always +3 (Sc, Y, La)	VIA	Always -2 (O^2-, S^2-, Se^2-, Te^2-) as an anion
IVB- VIIIB	Commonly +2 and +3 (e.g., Cr, Mn, Fe, Co, Ni)	VIIA	Always -1 (F^-, Cl^-, Br^-, I^-) as an anion
IB	Cu (+1, +2); Ag (+1); Au (+1, +3)	hydrogen	Always -1 (H^-) as anion; but +1 otherwise
IIB	Zn and Cd (+2); Hg (+1, +2)
IIIA	Al and Ga (+3); In and Tl (+1, +3)
IVA	Sn and Pb (+2, +4)
VA	Bi (+3, +5)

Note: this list contains commonly-found oxidation states. Oxidation states not shown exist, but they are less-frequently encountered and therefore not "common." Other oxidation states are commonly encountered for metals in polyatomic ions, where the metal is not the cation of a compound. When naming compounds, the oxidation state of the metal cation is given only if the metal has more than one common oxidation state (e.g., Iron(III) or Iron(II) in the name).