Binary Compounds

Binary compounds contain only two elements.All binary compounds end in -ide.

They are divided into two types, each of which has different rules for how to name them and write their formulas.IONIC = metal +

nonmetal

COVALENT = nonmetal + nonmetal

Ionic CompoundsMetal + Nonmetal

Ionic compounds are held together by the opposite charge of the metal (+) and the nonmetal (-).

The SUM of the charges of all the atoms must equal ZERO.

Ionic Examples

Na+1 and Cl-1 =

Na+1 and O-2 =

Ca+2 and O-2 =

Al+3 and Cl-1 =

Al+3 and O-2 =

Al+3 and N-3 =

NaCl sodium chloride

Na2O sodium oxide

CaO calcium oxide

AlCl3 aluminum chloride

Al2O3 aluminum oxide

AlN aluminum nitride

Transition Metals

Transition metals can have different charges in different compounds.

So … the name of the compound includes a roman numeral that indicates the charge on the transition metal.EXAMPLES:

iron (II) chloride:

gold (I) sulfide:

Fe+2 and Cl-1 = FeCl2

Au+1 and S-2 = Au2S

Transition Metals - cont.

When you name a compound with a transition metal you must determine the charge on the metal.

Remember … the sum of the charges of all atoms must be zero. So use the charge on the nonmetal to figure out the charge on the transition metal.EXAMPLES:

CuF

Mn2O3

SnO2

Cu + (-1) =0 Cu=+1 copper (I) fluoride

2Mn + 3(-2) = 0 Mn=+3 manganese(III) oxide

Sn + 2(-2) = 0 Sn=+4 tin (IV) oxide

Covalent CompoundsNonmetal + Nonmetal

Covalent compounds are held together by shared pairs of electrons. No ions are involved.

Naming covalent compounds involves using a prefix system that directly indicates the number of atoms of each element in one molecule of the compound .

Covalent Prefixes

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

NOTE:Mono- is only used on the second element.

In front of “oxide”, drop the “a” or “o” at the end of the prefix.

Covalent Examples

CO CO2

PCl3

P2I4

N2O

S2F10

AsI2

B4C

= carbon monoxide= carbon dioxide= phosphorus trichloride= diphosphorus tetraiodide= dinitrogen monoxide= disulfur decafluoride= arsenic diiodide= tetraboron monocarbide

QuickTime™ and a decompressor

are needed to see this picture.

Polyatomic Ions

Polayatomic ions are ions made from more than one atom, and usually more than one element. There is a single charge for the entire ion.

They are ions, and are named as ionic compounds are.

Parentheses are used when more than one of a polyatomic ion is needed.

Examples of Polyatomic ions

ammonium NH4+1

acetate C2H3O2

-1

nitrite NO2-1

nitrate NO3-1

sulfate SO4-1

oxylate C2O4-2

phosphate PO4-3

hydroxide OH-1

cyanide CN-1

•Most polyatomic ions end in “-ate” or “-ite”. This separates them from binary compounds that end in “-ide”.

•The positive polyatomic ion ammonium ends in “-ium”, like many metals.

•Beware hydroxide and cyanide, which break the normal rules and end in “-ide” but are polyatomic ions.

Polyatomic Ionic Examples

sodium acetate =

calcium nitrite =

copper (II) phosphate =

manganese (II) sulfate =

aluminum cyanide =

ammonium sulfide =

Na+1 and C2H3O2-1 = NaC2H3O2

Ca+2 and NO2-1 =

Ca(NO2)2

Cu+2 and PO4-3 =

Cu3(PO4)2

Mn+2 and SO4-2 = MnSO4

Al+3 and CN-1 = Al(CN)3

NH4+1 and S-2 = (NH4)2S

AcidsAqueous acids have their own

nomenclature, based on their negative ion.

if ION ends in: then ACID is named:

-ate -ic acid -ite -ous acid -ide hydro- & -ic acid

Acid Examples HCl = hydrogen chloride -> hydrochloric acidHNO3 = hydrogen nitrate -> nitric acid

HNO2 = hydrogen nitrite -> nitrous acid

H2PO4 (aq) =

HI (aq) =

H2SO3 (aq) =

H2C7H6O5 (aq)=

HCN (aq) =

phosphoric acid

hydroiodic acid

sulfurous acid

citric acid

hydrocyanic acid