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.
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.
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;
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
Al2O3 aluminum 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
FeBr2: 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
HCl: Hydrochloric acid
HBr: Hydrobromic acid
HI: Hydroiodic acid
H2S: Hydro sulfuric acid
f) Some Common Polyatomic Ions:
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;
I, II, III and IV are true.
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