VALANCIES

Valency of positive ions. Depending upon the charge present on them a positive ions may be monovalent, bivalent, trivalent, tetravalent etc.. These are listed.

Hydrogen	H+	Barium	Ba2+	Aluminium	Al3+
Potassium	K+	Calcium	Ca2+	Chromium	Cr3+
Sodium	Na+	Magnesium	Mg2+	Iron	Fe3+
Silver	Ag+	Zinc	Zn2+
Copper	Cu+	Cobalt	Co2+
Gold	Au+	Copper	Cu2+
Ammonium	(NH4)+	Iron	Fe2+

Some elements have shown more than one valency. In such cases, Roman Numerals are used to denote the valencies. These are put in bracket e.g. copper (I) and copper (II) ; similarly, iron (II) and iron (III).

Valency of negative ions. Like positive ions, negative ions may also be monovalent, bivalent, trivalent, tetravalent etc. in nature.                              

Monovalent		Bivalent		Trivalent
Chloride	CI–	Sulphide	S2–	Nitride	N3–
Bromide	Br–	Oxide	O2–	Phosphide	P3–
Iodide	I –	Carbonate	(CO3) 2–	Phosphate	(PO4) 3–
Hydroxide	(OH) –	Sulphate	(SO4) 2–	Borate	(BO3) 3–
Nitrate	(NO3) –	Sulphite	(SO3) 2–	Arsenate	(AsO3)3–­
Nitrite	(NO2) –	Manganate	(MnO4) 2–
Bicarbonate	(HCO3) –	Oxalate	(C2O4) 2–­
Cyanide	(CN) –	Chromate	(CrO4) 2–­
Permanganate	(MnO4) –	Dichromate	(Cr2O7) 2–
Hydrogen sulphate	(HSO4) –

Symbols

Element	Symbol	Element	Symbol	Eelement	Symbol	Element	Symbol
Boron	B	Oxygen	O	Barium	Ba	Molybdenum	Mo
Carbon	C	Phosphorus	P	Beryllium	Be	Nickel	Ni
Fluorine	F	Sulphur	S	Bismuth	Bi	Neon	Ne
Hydrogen	H	Uranium	U	Bromine	Br	Strontium	Sr
Iodine	I	Vanadium	V	Calcium	Ca	Silicon	Si
Aluminium	Al	Lithium	Li	Chlorine	Cl	Nitrogen	N
Argon	Ar	Magnesium	Mg	Cobalt	Co	Platinum	Pt
Arsenic	As	Manganese	Mn	Chromium	Cr	Zinc	Zn