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Compounds: Naming and Writing

Writing Basics:

1. You will encounter 2 kinds of compoundsa. Binary compounds : combination of 2 single ionsb. Ternary compounds : combination of 2 polyatomic ions or single ion and a

polyatomic ion

2. We always write the + ion first before the ion. The left side is always a positive ion andthe right side is always a negative ion.3. The charge of the + ion is the subscript of the ion and vice versa. We call this the cross

charge method.

Na+1 + O-2 = Na2O

4. If its a ternary compound which is a combination of a single ion and a polyatomic ion weenclose the polyatomic ion in a parenthesis then cross the charge.

Ca+2 + PO4-3 = Ca3(PO4)2

5. If they have the same numerical charge, we cancel them and simplify them to 1. When wehave a value of 1 for the charge we dont write 1 anymore as a subscript.

Mg+2 + S-2 = MgS

Al +3 + PO3-3 = AlPO3

6. If the charges could be simplified, simplify them then write the new values as thesubscripts

Sr+2 = 1 + C -4 = 2 = Sr2C

Ra +2 = 1 + SiO4 -4 = 2 = Ra2SiO

Writing them back to ions:**From compounds back to ions we just simply reverse the cross charge method.**It will be helpful if you know the charges of the involved ions.

Ga2O3 = Ga+3 + O -2

Li2S = Li+1 + S -2(it is understood that if there are no values written, it means

the value is one.)

GeO2 = Ge+4 + O-2(For these cases, identify the oxidation numbers of the

ions, they might be simplified so better trace their values first)

** Identifying the ions of ternary compounds could be confusing but here are some tips.

1. Most of the + ions are single ions except for ammonium (NH4+1) and hydronium (H3O+1), if

you didnt encounter this 2 ions in the compound, then expect to have a single positiveion.2. The first element in the compound is the + ion then its subscript is the charge of the

negative ion.3. After the first element, if there are 2 or more elements then you can say it is a polyatomic

ion. If its in a parenthesis the subscript written outside the parenthesis is the charge ofthe positive ion. If there is no parenthesis the charge of the positive ion is 1.

Al2(SO4)3 = Al+3 + SO4

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Na3BO3 = Na+1 + BO3

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Naming Compounds

General Rules:

The first elements first letter is written in capital letters then the 2nd would be in small letters

The cross charge method is always observed in identifying the symbol

The first ion is always positive and the 2nd

is always negative For oxyanions:

o Per (short for hyper) is used as a prefix for the highest value available then it would have

a suffix ate. Like in perchlorate (ClO4)o Ate is used as a suffix for higher values. Like in phosphate (PO4) and sulfate (SO4)

o Ite is used as a suffix for lower values. Like in phosphite (PO3) and sulfite (SO3)

o Hypo is used as a prefix for the lowest value available then it would have a suffix ite.

Like in hypochlorite (ClO)

A. Binary Salts: Single Metal ion + single negative ion

Rule:

The metal ions name is retained

We take the stem of the negative ion then add the suffix ide

The ide suffix indicates a single negative ion, an exemption would be hydroxide (OH).

Ex:Sodium chloride NaClCalcium hydride CaH2Aluminum bromide AlBr3

B. Ternary Salts: Metal ion + negative polyatomic ion

Rule:

Both names are retained

Ex:Beryllium sulfate BeSO4Calcium phosphate Ca3(PO4)2Aluminum acetate Al(C2H3O2)3Lithium nitrite LiNO2

C. Metal ions with more than 2 O.N.s

C.1. Classical Method

Rule:

The metal ion would either use its Latin or English name

Only applicable to the first 2 lower ON of the metal ion (like manganese that has 4 ONs it will onlybe applicable to +2 and +3 charges)

Get the stem of the metal ion then add ic for the higher ON then ous for the lower ON

Negative ions will just follow previous rules

Ex:Ferric oxide = Fe2O3 (Fe +3 and O -2)Ferrous oxide = FeO (Fe +2 and O -2)Plumbic sulfate = Pb(SO4)2 (Pb +4 and SO4 -2)Plumbous sulfite = PbSO3 (Pb +2 and SO3 -2)Manganic sulfide = Mn2S3 (Mn +3 and S -2)Manganous sulfide = MnS (Mn +2 and S -2)

C.2. Stock Method

Rule:

Applicable to all ON of metal ions

The English names of metal ions are used

The ONs are written in Roman Numerals enclosed in a parenthesis after the name of the metal ion

Then same rules will apply for the negative ions

Ex:Mercury (I) oxide = Hg2OMercury (II) oxide = HgOLead (II) acetate = Pb(C2H3O2)2

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Lead (IV) carbide = PbC (Pb+4 and C+4)

D. Binary Non-metals: Non-metal to non-metal

Rule:

We use greek prefixes and place them in front of the elements name

We follow the same rules for naming binary salts, retain the name of the first element and for the 2element get the stem then add ide to indicate it is a binary compound. The greek prefix is then

added to indicate the number of atoms present in the compound.

Ex:Carbon monoxide = CO

Trinitrogen tetrasulfide = N3S4Carbon tetrachloride = CCl4

Tetranitrogen hexoxide = N4O6Carbon heptasulfide = CS7

Rules of grammar are applied here, when a is followed by a vowel sound (like o) we drop a. samerule will apply for o followed by o (Ex: heptoxide = O7, monoxide = O)

If the first element has only one atom, mono is not written anymore.

E. Binary acids: Hydrogen + single ion

Rule:

Dry form : Just follow the standard metal non-metal naming method (Hydrogen + stem of negativeion + ide)

Aqueous form : Add stem Hydro + stem of single ion + ic and the word acid.

Ex:Hydrogen chloride (Dry Form) = Hydrochloric acid (Aqueous Form) = HClHydrogen bromide (DF) = Hydrobromic acid (AF) = HBrHydrogen sulfide (DF) = Hydrosulfuric acid (AF) = H2SHydrogen iodide (DF) = Hydroiodic acid (AF) = HI

The stem for sulfur is not used in acid form but taken as a whole, like hydrosulfuric and sulfuricacids.

F. Ternary acids: Hydrogen + poly atomic ion

Rule:

Dry form : Hydrogen and polyatomic ions name are retained

Aqueous form : we change the suffix ate to ic and ite to ous then add acid

Ex:Hydrogen sulfate (DF) = Sulfuric acid (AF) = H2SO4Hydrogen sulfite (DF) = Sulfurous acid (AF) = H2SO3

Hydrogen nitrate (DF) = Nitric acid (AF) = HNO3Hydrogen nitrite (DF) = Nitrous acid (AF) = HNO2Hydrogen acetate (DF) = Acetic acid (AF) = HC2H3O2

G. Bases: Metal ion + hydroxide (OH)

Rule:

Same methods for naming metal non metal combinations are followed.

Metal ions name is retained then we write hydroxide (OH)

Methods for classical and stock methods are applied

Ex:Aluminum hydroxide = Al(OH)3

Sodium hydroxide = NaOHFerric hydroxide = Fe(OH)3Ferrous hydroxide = Fe(OH)2Mercury (I) hydroxide = HgOHMercury (II) hydroxide = Hg(OH)2