Ch. 9:Ch. 9:Chemical NomenclatureChemical Nomenclature

Names and FormulasNames and Formulas

Review… Ionic Review… Ionic ChargesCharges1+ 2+ 3+ 3- 2- 1-

Review… IonsReview… Ions

• Cation: + charged ion

ex: Na (sodium) Na+ (sodium ion)

• Anion: - charged ion

ex: Br (Bromine) Br - (Bromine ion)

• Polyatomic Ion: a tightly bound group of atoms that form a molecule and have a + or – chargeex: NO3

- (nitrate ion)

Ionic FormulasIonic Formulas• + charge of a cation must balance with

the - charge of an anion

• So, net ionic charge of a formula = 0

• Number of atoms are determined by the charge of each cation and anion

ex: Ca2+ + Cl- CaCl2

(2+) + 2(1-) = 0

I.I.

Ionic FormulasIonic Formulas

• Binary compound: made of 2 elements

• Ternary compound: made of 3 elements

ex: H+ + (NO3)- H(NO3)

Ternary compound

Polyatomic Ion Polyatomic Ion FormulasFormulas• An ion formed from one atom is a

monatomic ion

• An ion formed from a compound (2 or

more atoms) is a polyatomic ion

ex: Na+ monatomic ion

NH4+ polyatomic ion

Naming Ionic Naming Ionic CompoundsCompounds

Binary Ionic Compounds consist of a Binary Ionic Compounds consist of a METAL METAL and a and a NON-METALNON-METAL

• The name of the metal (cation) is first• The name of the non-metal (anion) has

the suffix -ide added

ex: NaCl is Sodium Chloride

• Overall charge must equal zero.– If charges cancel, just write symbols.– If not, use subscripts to balance charges.

II.II.

Names of Common Names of Common IonsIons

Anions are named by adding the suffix -ide to the stem of the name of the nonmetal

Naming Transition MetalsNaming Transition Metals

•Transition metals can form more than one cation(they are essentially metals, so have tendency to lose valence electrons)

•To distinguish between them, the number of excess charges is written in roman numerals following the name of the metal, then by the word "ion".

For example:     Fe2+    iron (II) ionFe3+    iron (III) ion

Naming Polyatomic Naming Polyatomic IonsIons

There is no specific naming rule except that:

• Polyatomic cations are followed by “ion”

•Polyatomic anions add the suffix –ide to the end element (if they don’t contain an oxygen atom in the molecule)

ex: (cation) NH4

+ ammonium ion (anion) CN- cyanide HS- hydrogen sulfide

III.III.

Polyatomic Ion Polyatomic Ion NamesNames

• When two or more polyatomic ions consist of the same ions

• those containing more oxygen atoms end with the suffix "ate"

• those with the fewer oxygen atoms end with the suffix "ite".

ex: SO42- Sulfate SO3

2- Sulfite

NO3- Nitrate NO2

- Nitrite

Naming Molecular Naming Molecular CompoundsCompounds

• Molecular compounds = Covalent bonds

• Molecules generally consist of 2 NON-NON-METALSMETALS

• Molecular name starts with the element on the left side of the Periodic Table

• The second element has the suffix –ide

IV.IV.

ex: CO2 carbon dioxide

Naming Molecular Naming Molecular Compounds cont’d.Compounds cont’d.

Number of Atoms Prefix

1 Mono-

2 Di-

3 Tri-

4 Tetra-

5 Penta-

6 Hexa-

7 Hepta-

8 Octa-

9 Nona-

10 Deca-

•Greek prefixes are used for number of atoms

ex: CO carbon monoxide CO2 carbon dioxide N2O5 dinitrogen pentaoxide

Learning CheckLearning Check

1. aluminum oxide

a) Al2O3 b) AlO3 c) Al3O3

2. Potassium nitride

a) KN3 b) K2N3 c) K3N

3. Dihydrogen monoxide

a) H2O b) OH c) HO2

4. Tin(IV) nitrate

a) Sn(NO3)4 b) Sn(NO3)2 c) Sn4(NO3)

Learning CheckLearning CheckIonic Compounds:

CaCl2 ___________________

Al2O3 ___________________

Pb2+I ___________________

Polyatomic Ions:

H2S ___________________

CrO42-

___________________

SO42- ___________________

Ca2+(NO2-)2 ___________________

Molecular Compounds:

CCl4 ___________________

N2O ___________________