Molecular Compounds

Covalent Bonds

Also called covalent compounds

A molecule is a neutral group of atoms that are held together by covalent bonds

The valence e- are shared by the atoms

Covalent bonding usually occurs between 2 non-metals◦ H2O, CO2, O2, NO

Molecular Compounds

Naming Molecular Compounds Use prefixes 1 mono-

2 di-3 tri-4 tetra-5 penta-6 hexa-7 hepta-8 octa-9 nona-10 deca-

P4O10

N2O3

As2O5

OF2

Examples

Tetraphosphorous decoxide

Dinitrogen trioxide

Diarsenic pentoxide

Oxygen difluoride

NaBr

CH4

Fe2O3

CO2

CaO

NH4Cl

SiCl4

Ionic or CovalentIonic

Ionic

IonicIonic

Covalent

Covalent

Covalent

Sodium BromideCarbon tetrahydrideIron (III) oxide

Carbon dioxideCalcium oxide

Ammonium chlorideSilicon tetrachloride

H2

O2

N2

Cl2Br2

I2F2

Diatomic Molecules

7 diatomic molecules No noble gases Halogens and N, O, H They are all gases (not

noble gases) except for Br and I

“Honcl brif”

A formula that represents the lowest integral ratio of atoms of the elements in a compound

C2H4, C3H6 and C4H8 all have the same empirical formula:◦ CH2

Examples◦ C2H6O2

◦ NaC4H6O2

Empirical Formula

CH3O

NaC4H6O2

Anion Acid Name Example

-ide hydro—ic HCl hydrochloric acid

-ite --ous HNO2

nitrous acid

-ate --ic HNO3

nitric acid

Naming Acids

**only binary acids use “hydro”

H2SO4

HF

H3PO4

H2SO3

H2CO3

HNO3

Try these. . .Sulfuric AcidHydrofluoric AcidPhosphoric Acid

Sulfurous Acid

Carbonic Acid

Nitric Acid

More Practice. . . Calcium bromide

Chromium (III) acetate

Barium sulfate

Copper (I) sulfide

Sulfur hexafluoride

CaBr2

Cr(C2H3O2)3

BaSO4

Cu2S

SF6

Cr2(C2O4)3

Hg(CN)2

Cu(ClO4)2

ZnC4H4O6

More Practice. . .

Chromium (III) oxalateMercury (II) cyanide

Copper (II) perchlorateZinc tartrate

The mass of a compound

In order to calculate molar mass (also called molecular weight) you add up the masses of each element in the compound◦ Be aware of subscript numbers that designate the

amount of atoms per element

You get the masses from the periodic table

**be careful when rounding the mass

How to Calculate Molar Mass

NaCl◦ Na = 23 g/mol◦ Cl = 35.5 g/mol

H2O◦ H = 1 g/mol (but there are 2) = 2 g/mol◦ O = 16 g/mol

HNO3

◦ H = 1 g/mol◦ N = 14 g/mol◦ O = 16 g/mol (but there are 3) = 48 g/mol

Ba(NO3)2

◦ Ba = 137.3 g/mol◦ N = 14 g/mol (but there are 2) = 28 g/mol◦ O = 16 g/mol (but there are 6) = 96 g/mol

Examples 58.5 g/mol

18 g/mol

63 g/mol

261.3 g/mol