Atoms and Molecules Notes

• Matter is called ‘padarth’ in Hindi.
• An Indian philosopher, Maharishi Kanad, said that if we go on dividing matter (padarth), we will get smaller and smaller particles of matter.
• We will get the smallest particle of matter, which cannot be divided any further.

Classification of matter:

• There are three important laws of chemical combination. These are:

1. Law of conservation of mass (or matter)
2. Law of constant proportions
3. Law of multiple proportions

Law of Conservation of Mass:

• John Dalton (1766-1844) developed the first useful atomic theory of matter around 1803.
• All matter, whether an element, a compound or a mixture is composed of small particles called atoms.
• The postulates of this theory may be stated as follows:

1. All matter is made of very tiny particles called atoms.