CLASSIFICATION OF PURE SUBSTANCES
A single form of matter which contain only a single type of particles is known as pure substances. Pure substances can be classified as elements and compounds
Elements
An element is a basic form of matter that cannot be broken down into simpler substance by chemical reaction.
Elements are divided into metals , non metals and metalloids. There are more than 100 elements known. Majority of them are solid, eleven elements are in gaseous state at room temperature and two in liquid for at room temperature mercury and bromine.
Compounds
A compound is a pure substance composed of two or more elements, chemically combined with one another in a fixed proportion. Composition, texture and colour of a compound is same throughout. Constituents can be separated only by chemical or electrochemical reactions.