Discuss the characteristics of
(a) element
(b) mixture
(c ) compound

Explanation

(a) Element : An element is a substance in a molecule which is constituted of only one kind of atoms and cannot be further divided by any physical or chemical means.
Example : Hydrogen, oxygen, chlorine, sodium, potassium etc. are the examples of elements.
Molecules of these substances consist of only one type of atoms. Molecules of different elements may contain different number of atoms.
(b) Mixture : A mixture is a substance which is formed by mixing two or more substances (elements, compounds or both) physically in any proportion. No chemical reaction takes place during the formation of a mixture and all the constituents of mixture retain their properties. Constituents of mixture can easily be separated by physical means.
Example : solution of sugar and water is a mixture in which sugar and water both retain their properties and can be separated by a simple physical process that is evaporation. Muddy water is another example of mixture of mud and water which can easily be separated by filtration.
(c ) Compound : A compound is a substance which is formed due to the chemical combination of two or more elements in a definite proportion by mass. The constituents of do not retain their properties and they can be separated only by chemical means.
Example : Water, carbon dioxide, hydrochloric acid, sodium chlocium carbonate etc, are a few examples of compounds. A molecule of carbon dioxide is constituted of a carbon atom and two oxygen atoms. Two atoms of hydrogen and one atom of oxygen combine chemically to form a molecule of water.