Discuss the beta decay process with examples.

Explanation

(i) In beta decay, a radioactive nucleus emits either electron or positron. If electron `(e^(-))` is emitted, it is called `beta^(-)` decay and if positron `(e^(+))` is emitted, it is called `beta^(+)` decay.
(ii) The positron is an anti-particle of an electron whose mass is same as that of electron and charge is opposite to that of electron - that is +e. Both positron and electron are referred to as beta particles.
(iii) `beta^(-)` decay : In `beta^(-)` decay, the atomic number of the nucleus increases by one but mass number remains the same. This decay is represents by
`""_(Z)^(A)Xto""_(Z+1)^(A)Y+e^(-)+barv" "...(1)`
(iv) It implies that the element X becomes Y by giving out an electron and antineutrino `(barv)`. In each `beta^(-)` decay, one neutron in the nucleus of X is converted into a proton by emitting an electron `(e^(-))` and antineutrino. It is given by
`n to p+e^(-)+barv`
Where p-proton, `barv` antineutrino.
Ex : Carbon `(""_(6)^(14)C)` is converted into nitrogen `(""_(7)^(14)N)` through `beta^(-)` decay
`""_(6)^(14)Cto""_(7)^(14)N+e^(-)+barv`
(v) `beta^(+)` decay : In `beta^(+)` decay, the atomic number is decreased by one and the mass number remains the same. This decay is represented by
`""_(Z)^(A)Xto""_(Z-1)^(A)Y+e^(+)+v`
(vi) It implies that the element X becomes Y by giving out an positron and neutrino (v), for each `beta^(+)` decay, a proton in the nucleus of X is converted into a neutron by emitting a positron `(e^(+))` and a neutrino. It is given by
`p ton+e^(+)+v`
(vii) However a single proton (not inside any nucleus) cannot have `beta^(+)` decay due to energy conservation, because neutron mass is larger than proton mass. But a single neutron (not inside any nucleus) can have `beta^(-)` decay.
Example : Sodium `(""_(11)^(22)Na)` is converted into neon `(""_(10)^(22)Ne)` through `beta^(+)` decay.
`""_(11)^(22)Nato""_(10)^(22)Ne+e^(+)+v`
(viii) The electron or positron which comes out from nuclei during beta decay never present inside the nuclei rather they are produced during the conversion of neutron into proton or proton into neutron inside the nucleus.