Day: May 20, 2022

class 9, chapter 2, notes (part – 1)

Chemical nature of matter

On the basis of chemical nature, the matter is known to exist either as a pure substance or as a mixture of two or more pure substance. A substance is a kind of matter that cannot be separated into other kinds of matter by any physical process.

A pure substance defined as one which contains only one kind of atoms or molecules. Such as water. On the bases of constitution it is of two types:

  • Substance which is made of only one kind of atoms is called an element while which is made up of only one kind of molecules is called a compound.  

Characteristics of pure substance

  • A pure substance is uniform in its composition.
  • A pure substance cannot be separated into different materials by any physical process.
  • A pure substance contains one type of atoms or molecules and has a definite composition.
  • A pure substance has fixed melting and boiling points.