Properties and Naming Simple Compounds (Nomenculature) with Example

Properties and Naming Simple Compound with Examples

More than one element come together and comprise compounds. As we discussed in previous topics, compounds are pure substances. Building blocks of compounds are molecules including more than one elements.

H₂O

H₂+1/2O₂→H₂O

H₂: Molecule

O₂: Molecule

We examine naming in two steps, first we learn how to write simple formula, then we learn real (compound, molecule) formula.

1. Simple Formula: We can understand types of elements and ratio of them from simple formula. On the contrary, we can not understand physical and chemical properties of matter by looking at its simple formula.

(NO₂)n

(CH₂)n

(NO₂)n

where n is variable.

2. Real Formula: Types of elements and “n” number in the simple formula is given in real formula.

C₆H₁₂O₆: Real Formula

(CH₂O)n: Simple Formula where n=6

Real formula gives us:

• Types of compound
• Types of elements
• Molecule mass of compound
• “n” number in the simple formula

We first examine compounds formed by two elements or binary compounds. One metal can not form compound with another metal. Thus, if one of the elements is metal, then other one must be nonmetal or two of the elements must be nonmetal to form compound. Oxygen is one of the elements joining structure of most of the compounds. Let me explain compounds including oxygen first.

a) Nonmetal+Oxygen Compounds:

We first say name of nonmetal element then number of oxygen atoms in the compound and word “oxide”. For example;

I. CO: Carbon Monoxide (one carbon atom and one oxygen atom)

II. CO₂: Carbon Dioxide (one carbon atom and two oxygen atoms)

III. P₂O₅: Phosphor Penta Oxide (two Phosphor atom and 5 oxygen atoms)

In first example, we do not write mono in front of Carbon atom, in general number of atoms does not written in front of first element. However, there are some exceptions;

NO, N₂O

If we say nitrogen monoxide to first compound, and second compound we can mix them. Thus, we must put “di” in front of nitrogen in second compound.

NO: nitrogen monoxide

N₂O: di nitrogen monoxide

Prefixes we use in naming compounds are;

one: mono            five: penta              nine: nona

two: di                  six: hexa                ten: deca

three: tri               seven: hepta

four: tetra             eight: octa

b) Metal+Oxygen Compounds:

Naming these compounds are different from naming nonmetal+oxygen compounds. Prefixes given above are not used in naming these compounds. On the contrary, oxidation number of metals are given in these compounds if necessary. Better understanding examine following examples;

CaO: Calcium Oxide (Since calcium has one oxidation number +2, we do not write it.)

Cu₂O :Copper I Oxide

CuO: Copper II Oxide   (Since copper has two oxidation number we write them.)

Na₂O: Sodium Oxide

Al₂O₃aluminum oxide

FeO: Iron (II) Oxide

Fe₂O₃: Iron (III) Oxide  (Iron has two oxidation numbers +2 and +3 thus we must mention oxidation numbers)

c) Nonmetal+ Nonmetal Compounds:

In these types of compounds, you must first write element having “+” oxidation number and then “-” number of atoms in second nonmetal element or more metallic element is written first. You must also add “ide” suffix after second element.

CS₂: Carbon disulphide

CCl₄: Carbon tetra chloride

ICl: Iode mono chloride

PI₃: Phosphorus tri iodide

P₂S₅:(Di) Phosphorus pentasulfide

d) Metal+Nonmetal Compounds:

In naming metal+nonmetal compounds, we do not say number of atoms in elements, however, we must say oxidation number of elements if it has more than one oxidation number. Finally, as in the previous examples, we must ad “ide” suffix after second element. Examine following examples for better understanding;

MgI₂: Magnesium Iodide

FeBr_{2 :} Iron II Bromide

FeBr₃: Iron III Bromide

NaCl: Sodium Chloride

e) Naming Binary Acids:

If a binary compound dissolves in water and contains H atom, we call these compounds as acid. When naming these acids we follow given steps. Hydro+nonmetal element+“ic” suffix+ acid

Examples:

HCl: Hydrochloric acid

HBr: Hydrobromic acid

HI: Hydroiodic acid

H₂S: Hydro sulfuric acid

f) Some Common Polyatomic Ions:

NH₄⁺ Ammonium

OH^- Hydroxide

CO₃^-2 Carbonate

PO₄^-3 Phosphate

SO₄^-2Sulfate

SO₃^-2Sulfide

NO₃^- Nitrate

NO₂^- Nitrite

Example: Which one of the following name of compound is false.

I. Hg₂Cl₂ Mercury I Chloride

II. NO₃ Nitrogen Trioxide

III. K₂S Potassium Sulfide

IV. CO Carbon Monoxide

V. NaCl Sodium Chlore

In ionic compounds we first write cation then write anion. We add “ide” suffix after anion, thus in V. Name of compound must be;

NaCl=Sodium Chloride

I, II, III and IV are true.

Matters and Properties of Matters Exams and Problem Solutions