Unit 4: Chemical Nomenclature

Section 2: Stock System Ion Compounds

Binary Compounds with Stock System Ions

• Stock System Ion - ion that can have more than one possible charge– Example: Fe2+ and Fe3+

• Most transition metals are stock system ions!

Naming Stock System Ion Compounds

• Same method as basic binary compounds, except we need to know WHICH cation is being used

• We designate this with a roman numeral in parentheses behind the metal name

• Roman numerals are used to specify the charge:– 1 I– 2 II– 3 III– 4 IV- 5 V

It makes a difference!!!

Copper (I) chloride

Copper (II) chloride

BUT… HOW DO I FIGURE OUT WHICH ION WENT

INTO THE COMPUND?!?!?!

DON’T FREAK OUT! WE’LL

MAKE IT THROUG

H!

Reverse Criss-Cross!

• Remember, in the formula, the bottom numbers CAME from the criss-crossed charges.

• So REVERSE criss-cross to get the charges…

–CaCl2 Ca2+ and Cl1-

Examples of Stock System Compounds• Tin and Chlorine

– Formula 1: SnCl2 Sn2+ and Cl1-

– Name 1: Tin (II) chloride

- Formula 2: SnCl4 Sn4+ and Cl1-

- Name 2: Tin (IV) chloride

Examples of Stock System Compounds

• Copper and Nitrate– Formula 1: CuNO3 Cu+ and NO3

1-

– Name 1: Copper (I) nitrate

– Formula 2: Cu(NO3)2 Cu2+ and NO3

1-

– Name 2: Copper (II) nitrate

Let’s practice!!!