Nomenclature

Naming compounds Writing Formulas

Naming Compounds

Binary CompoundsCompounds that contain two elements

• Name the first element• Name the second element using an “ide”

ending• Check the oxidation number of the first

element• If it has more than one positive value, use a

Roman numeral to indicate the number that was used

CaCl2

Calcium Calcium chloride Ca is +2 only

No Roman numeral needed

Calcium chloride

CCl4

Carbon Carbon chloride C is -4, +2 and +4

Since there are two positive choices, use a Roman numeral

C Cl4Carbon IV chloride

-1

-4+4

+4

=0

Naming Compounds

Ternary Compounds Compounds that contain more than two elements

• Polyatomic ion is present• Two or more elements that join together and act like one

substance• Found on Table E

Identify the polyatomic used Name the first substance Name the second substance Check the oxidation number of the first element

• If it has more than one positive value, use a Roman numeral to indicate the number that was used

K2SO4

Potassium Potassium sulfate Potassium is +1 only

No Roman numeral is needed

Potassium sulfate

Cu(NO3) 2

Copper Copper nitrate Copper can be +1 or +2

Needs a Roman numeral

Cu (NO3)2

-1

-2 =0

+2

+2

Copper II nitrate

NH4Cl

Ammonium Ammonium chloride Ammonium ion is +1

No choice means no Roman numeral needed

Ammonium chloride

Prefix System

Use a prefix INSTEAD OF a Roman numeralMono

1 only used for the 2nd elementDi

2 elementsTri

3 elementsTetra

4 elements

CO2

Carbon dioxide

Suffix System

Used INSTEAD OF a Roman numeral“-ic

Highest oxidation state“-ous”

Lowest positive oxidation state

NiCl2

Nickel II chloride

Nickelous chloride

B. Writing Formulas

Use ending to tell if compound is binary or ternary

Binary usually ends in “ide”• [except hydroxide and cyanide]

Ternary usually ends in “ate” or “ite” Write the symbols Assign oxidation numbers

Positive atom on left, negative on right Reduce if possible and “criss-cross”

These numbers become the subscripts of the formula

Strontium phosphide

“ide” means binary Strontium (Sr) Phosphide is phosphorus (P) Sr+2 P-3

Sr3P2

Iron II Oxide

“ide” means binary Iron (Fe) Oxide is oxygen (O) Fe+2 O-2

Fe2O2

reduce

FeO

Manganese IV Carbonate

“ate” means ternary Manganese (Mn) Carbonate is a polyatomic ion

(CO3-2)

Mn+4 CO3-2

Mn2(CO3 )4

reduce

Mn (CO3 )2

Ferrous sulfide ferr-

represents Fe (iron) -ous

represents lowest positive state sulfide

represents sulfur Fe+2 S-2

Fe2S2 reduces to

• FeS

Diphosphorus trioxide

NO CHARGES ASSIGNED

NO CRISS-CROSSING

DiphosphorusP2

TrioxideO3

Formula

P2O3