Common and Polyatomic Ions Study Guide

Overview of Polyatomic Ions

• Definition: Polyatomic ions occur when many atoms combine to form a single unit with a unique charge.

• General characteristics: These molecular ions consist of multiple atoms covalently bonded, yet they carry an overall electrical charge that applies to the entire group.

Common Polyatomic Cations

• Ammonium- Formula: $NH_4^+$

• Hydronium- Formula: $H_3O^+$

• Ammonia- Formula: $NH_3$

Common Polyatomic Anions with -1 Charge

• Hydroxide- Formula: $OH^-$

• Cyanide- Formula: $CN^-$

• Nitrite- Formula: $NO_2^-$

• Nitrate- Formula: $NO_3^-$

• Hypochlorite- Formula: $ClO^-$

• Chlorite- Formula: $ClO_2^-$

• Chlorate- Formula: $ClO_3^-$

• Perchlorate- Formula: $ClO^-$

• Acetate- Formula: $CH<em>3COO^-$ or $C</em>2H<em>3O</em>2^-$

• Permanganate- Formula: $MnO_4^-$

• Formate- Formula: $CHO_2^-$

• Hydrogen carbonate (also known as Bicarbonate)- Formula: $HCO_3^-$

• Hydrogen sulfite (also known as Bisulfite)- Formula: $HSO_3^-$

• Hydrogen sulfate (also known as Bisulfate)- Formula: $HSO_4^-$

• Dihydrogen phosphate- Formula: $H<em>2PO</em>4^-$

• Bromate- Formula: $BrO_3^{1-}$

• Iodate- Formula: $IO_3^{1-}$

Common Polyatomic Anions with -2 Charge

• Peroxide- Formula: $O_2^{2-}$

• Carbonate- Formula: $CO_3^{2-}$

• Oxalate- Formula: $C<em>2O</em>4^{2-}$

• Sulfite- Formula: $SO_3^{2-}$

• Sulfate- Formula: $SO^{2-}$

• Thiosulfate- Formula: $S<em>2O</em>3^{2-}$

• Silicate- Formula: $SiO_3^{2-}$

• Chromate- Formula: $CrO_4^{2-}$

• Dichromate- Formula: $Cr<em>2O</em>7^{2-}$

• Hydrogen phosphate- Formula: $HPO^{2-}$

Common Polyatomic Anions with -3 Charge

• Phosphite- Formula: $PO_3^{3-}$

• Phosphate- Formula: $PO_4^{3-}$

• Arsenate- Formula: $AsO_4^{3-}$

• Borate- Formula: $BO_3^{3-}$

Log and Date Information

• Documentation Date: Sept 2nd, tues.