A compound is a pure substance which is formed due to the chemical combination of two or more elements in a fixed ratio by mass. The properties of a compound are different from those of its constituents. Water, carbon dioxide, sodium chloride etc. are few examples of compounds. A molecule of water is composed of one oxygen atom and two hydrogen atoms in the ratio 1:2 by volume or 8:1 by mass.
Classification of Compounds
Based on the origin of chemical constituents, compounds are classified as inorganic compounds and organic compounds.
a. Inorganic compounds
Compounds obtained from non living sources such as rock, minerals etc. , are called inorganic compounds. Example: Chalk, baking powder etc. ,
b. Organic compounds
Compounds obtained from living sources such as plants, animals etc. , are called organic compounds. Example: Protein, carbohydrates, etc. ,
Both inorganic and organic compounds exist in all three states ie., solids, liquids and gases. Let us learn about some important compounds in solid, liquid and gaseous states.
Some compounds that exist in solid state are given in Table 9.7.
Compounds which exist in liquid state are given in Table 9.8.
Some compounds exist in gaseous state also. They are given in Table 9.9.
Uses of Compounds
We use a number of compounds in our daily life. Some of them are listed in table 9.10.