DISCOVERY OF ATOM
Structure of atom of Class 9
DISCOVERY OF ATOM
- The idea of tiniest unit of matter (Anu and Parmanu) was propounded by maharishi Kanad in Vedic period in our country.
- Democritus, a Greek philosopher also proposed that matter is made up of extremely small particles, the “atom”. The name atom comes from Greek language.
- John Dalton in 1808 published theory of atom assuming that atoms are the ultimate indivisible particles of matter.
- Later the works of William Crookes (1878), J.J. Thomson (1897) and Goldstein proved that atom of any element contains smaller particles which are either positively charged or negatively charged.
- Work of Rutherford and Neils Bohr confirmed that an atom consists of three subatomic particles, that are electrons, protons and neutrons.
- ( It has been established that the central core of an atom consists of protons and neutrons and is commonly called nucleus. The electrons revolve around the nucleus.
- The atom as a whole is electrically neutral as the number of protons in it, is equal to the number of electrons.
An element is a pure substance which cannot be subdivided into two or more new substances by any means.
- Introduction
- FUNDAMENTAL PARTICLES OF AN ATOM
- VALENCY AND VALANCE ELECTRONS
- ISOTOPES
- ISOELECTRIC
- DISCOVERY OF ATOM
- SUB-ATOMIC PARTICLES OF ATOM
- THE STRUCTURE OF AN ATOM (ATOMIC MODELS)
- ATOMIC STRUCTURE
- ORBITALS
- ATOMIC NUMBER (Z)
- MASS NUMBER (A)
- what is isobar
- what is isotones
- Solved questions
- Exercise 1
- Exercise 2
- Exercise 3
- Exercise 4
- Exercise 5
- Exercise 6 (True and False)
