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Covalent NomenclatureCovalent Nomenclature

Covalent (molecular) compounds have both an empirical and a molecular formula.

An empirical formula is a formula showingAn empirical formula is a formula showing the simplest ratio in which the atomsthe simplest ratio in which the atoms combine to form a compound.combine to form a compound.

A molecular formula indicates the number of atoms of each element in one molecule of a substance.

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.

SomeSome Common Compounds

Compound EmpiricalFormula

MolecularFormula

water H2O H2O

ammonia NH3 NH3

hydrogenperoxide

HO H2O2

methane CH4 CH4

acetylene CH C2H2

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Traditional SystemTraditional System..

Prefixes are used with both the 1st named and 2nd named elements.

Never use mono- with the first named element!

MM with Junebug or Sophia.

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Prefixes Used With Traditional Prefixes Used With Traditional SystemSystem

..

Number of Atoms

Prefix Number of Atoms

Prefix

1 mono- 6 hexa-

2 di- 7 hepta-

3 tri- 8 octa-

4 tetra- 9 nona-

5 penta- 10 deca-

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Traditional NomenclatureTraditional Nomenclature.Chemical Formula Name

PF3phosphorus trifluoride

CCl4 carbon tetrachloride

PCl5 phosphorus pentachloride

N2O dinitrogen monoxide

NO2nitrogen dioxide

NO nitrogen monoxide

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Traditional NomenclatureTraditional Nomenclature.Name Chemical Formula

phosphorus trifluoride

PF3

carbon tetrachloride

CCl4

phosphorus pentachloride

PCl5

dinitrogen monoxide

N2O

nitrogen dioxide NO2

nitrogen monoxide NO

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Stock SystemStock System

Stock system never uses prefixes.

Stock system uses a roman numeral in parenthesis to indicate the apparent charge on the atom with a positive oxidation number.

Never mix and match the traditional and the

stock system!

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Stock System NomenclatureStock System Nomenclature.

Chemical Formula Name

PF3phosphorus(III) fluoride

CCl4 carbon(IV) chloride

PCl5 phosphorus(V) chloride

N2O nitrogen(I) oxide

NO2nitrogen(IV) oxide

NO nitrogen(II) oxide

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Stock System NomenclatureStock System Nomenclature.

Name Chemical Formula

phosphorus(III) fluoride

PF3

carbon(IV) chloride CCl4phosphorus(V) chloride

PCl5

nitrogen(I) oxide N2O

nitrogen(IV) oxide NO2

nitrogen(II) oxide NO