>>
Study Material >>
IIT JEE Chemistry >>
Physical Chemistry >>
Atomic Structure >>
Discovery of Neutron
DISCOVERY OF NEUTRON
After the discovery of electron and proton Rutherford (1920) had predicted the existence of a neutral fundamental particle. In 1932, Chadwick bombarded the element Beryllium with a-particles and noticed the emission of a radiation having the following characteristics.
- The radiation was highly penetrating.
- The radiation was unaffected by magnetic and electric fields which show that it is electrically neutral.
- It was found to have approximately the same mass as the protons.
The name ‘neutron’ was given to this sub-atomic particle. It is denoted by n or 1on. Bombardment of beryllium by α-particles results in the formation of carbon and neutrons are emitted.
α
Be — — → C + 1 n
0
At present there are a number of evidences which confirm that like electron, proton and neutron is also a fundamental constituent of atoms (a single exception is 11H atom which does not contain any neutron)
Mass of a neutron is 1.008930 amu (1.6753 x 10–24g or 1.6753 x 10–27 kg)
Neutron “A sub-atomic particle, which is a fundamental constituent of matter having mass approximately equal to the hydrogen atom and which is electrically neutral, is called a neutron”.
Illustration:-
The neutron is attracted towards
(A) Positive charged particles
(B) Negative charged particles
(C) Not attracted by any charge
(D) None of these
Solution:
Neutron is an uncharged particle. Hence (C) is correct.