Chemical Bonding Section 8

Chemical Bonding Unit 2

Section 8: Nomenclature

● Naming Ionic Compounds

Naming Binary Ionic Compounds

• _{The positive ion (cation) is written first.} • _{Takes the same name as the element.} • _{The negative ion (anion) is written last.}

• _{Take the first part of its elements name, and -ide is}

added to the end.

• Binary means two. Therefore, binary ionic compounds are ionic compounds with one type of cation and one type of anion.

• There is no rule for selecting the exact location where the original name ends and the -ide is added.

• People simply learn to recognize the correct

Naming Binary Ionic Compounds

• You need to know if an element forms cations with different charges.

• If it does, you need to specify the charge in Roman

numerals (d & p Block metals)

Ex) CuS is written as Copper(II) Sulfide

• Sulfide has to be S

• _{This only happens to elements that lose electrons}

(metals). Elements that gain electrons can always be predicted by their group in the periodic table.

• _{Sulfide has to be 2- because it is in group 6A and}

Naming Binary Ionic Compounds

Ex) CuBr is written as Copper (I) Bromide.

• _{Bromide has to be Br}

• _{Bromide has to be 1- because it is in group 7A and}

therefore gains one electron.

• _{To make a neutral compound the copper must lose one}

electron.

• _{Here we see copper forming an ion with a different}

Naming Binary Ionic Compounds

Ex) Fe₂O₃ is written as Iron (III) Oxide.

• _{Oxide has to be O}

2-• _{As there are three of them, they make up a charge of} 6-• _{The two irons must combine to form a charge of 6+}

Naming Binary Ionic Compounds

1. LiF Lithium Fluoride

2. CaBr₂ Calcium Bromide

3. K₂S Potassium Sulfide

4. FeS Iron (II) Sulfide

5. MgO Magnesium Oxide

6. MnO Manganese (II) Oxide

Naming Compounds with Polyatomic Ions

• _{For polyatomic ions, always use the name assigned}

to it.

- Do not add an additional suffix (such as -ide). e.g.) CO₃2- is the carbonate ion

Naming Compounds with Polyatomic Ions

• Ammonium, NH₄+, is the only polyatomic cation that you need to know.

e.g.) NH₄Cl is ammonium chloride

e.g.) NO₃- is the nitrate ion

The chloride still takes the -ide ending as it is monoatomic.(element by itself)

Hints for Learning the Names of Polyatomic Ions

• _{Only three polyatomic ions end in -ide}

• _CN- Cyanide

• _OH- Hydroxide

• O₂2- Peroxide

Hints for Learning the Names of Polyatomic Ions Oxoanions system

• _{Hypo-____- ite (2 less oxygens than ___ - ate)}

• _{______- ite (1 less oxygen than ___- ate)}

• ______ - ate

• _{Per - ____ - ate (1 more oxygen than ___ - ate)}

Hints for Learning the Names of Polyatomic Ions

● The example of Chlorate, ClO₃

-Hypochlorite ClO- (2 less oxygens than ___ -ate) Chlorite ClO₂- (1 less oxygen than ___ -ate)

Chlorate ClO₃

-Perchlorate ClO₄- (1 more oxygen than ___ -ate)

Hints for Learning the Names of Polyatomic Ions

The example of Sulfate (SO₄2-)

Sulfite SO₃2- (1 less oxygen than __ - ate)

Sulfate SO₄

Although there is no

hypo-___- ite

or

per-___- ate

for sulfate it still follows the same

rules.

Sulphite has 1 less oxygen than Sulphate!

Naming Binary Ionic Compounds

1. CuCO₃ Copper (II) Carbonate

2. K₂SO₃ Potassium Sulfite

3. Ca(ClO)₂ Calcium Hypochlorite

4. KClO₄ Potassium Perchlorate

5. NaClO₃ Sodium Chlorate

6. LiNO₂ Lithium Nitrite

7. LiNO₃ Lithium Nitrate

Recognizing Ionic Compounds and Naming

Ionic compounds contain either a metal and a

non-metal, or polyatomic ions.

If the first word in the compound is a

metal

Remember:

● _{Ionic formulas are the element symbols with}

the subscript (little number), such as PbO₂ or NaCl.

● _{Here we are going to learn how to write the}

Writing Ionic Formulas

• _{Ionic Compounds are neutral.}

o _{Thus, all charges must sum up to zero.}

• _{Charges come from the associated group (column}

number) in the periodic table, or a list.

• _{Parenthesis must be used when there is some multiple}

of a certain polyatomic ion.

Writing Ionic Formulas

Ex1) Calcium Chloride

• _{Calcium is always 2+ (Group 2A periodic table)} • _{-ide in chloride tells you it is monoatomic}

All anions (non-metals) carry the negative charge that corresponds to their group in the periodic table.

Group 7A is -1, Group 6A is -2, Group 5A is -3.

Ex1) Writing Ionic Formulas

Ca

2+

Cl

1-CaCl

₂

Criss-Cross or Cross Over Method

You need two chloride ions for every

one calcium ion to make the

Writing Ionic Formulas

Ex2) Iron (III) Sulfate

The Iron ion carries a charge of 3+, as the Roman numeral

is (III).

Ex2) Writing Ionic Formulas

Fe

3+

SO

4

2-Fe

₂

(SO

₄

)

₃

You need two iron (III) ions for every three sulfates to make the compound neutral.

Writing Ionic Formulas

1) Aluminum hydrogen sulfate Al(HSO₄)₃

2) Iron (II) oxide FeO

3) Iron (III) oxide Fe₂O₃

4) Strontium chromate SrCrO₄

5) Potassium chloride KCl

6) Ammonium Nitrate NH₄NO₃

Hydrates

• _{Hydrates are ionic compounds that trap water}

within their structures.

• _{Both the name and the chemical formula specify}

Writing Formulas for Hydrates

Write the formula for the ionic compound using the rules you learned earlier.

Add a dot and the correct number of waters taken from the

prefix.

e.g.) Sodium sulfate decahydrate

Writing Formulas for Hydrates

1) Barium Chloride Dihydrate BaCl₂ 2 H₂O