Question

What are the names of the three types of rays given off by a radioactive substance? Define the properties you know they possess. Why are the largest atoms radioactive?

Answer 1

A radioactive source emits three types of radiations. These are a
radiations, β and Y radiation.
α radiation

(i) a particles are He I iu m nucleus ₂He⁴.

(ii) a particles are positively charged.

(iii) The mass of each a particle is 4 a. m. u.

(iv) Ionization power of a particle is maximum. It is about 100 times more than that of β particles.

(v) α particle has velocity less than the velocity of light i.e 1 x 10⁷ ms^-1.

(vi) The penetrating power of a particle is least.

(vii) a particles are less deflected by electric and magnetic fields.

β particles

(i) β particles are like electrons _-1β°.

(ii) β particles are negatively charged.

(iii) The mass of each β particle is negligble.

(iv) Velocity of β particle is comparable to the velocity of light.

( v) Ionization power of β particle is about 100 times more than that of Y radiations.

(vi) Penetrating power of β particles is less but 100 times more than that of a particle.

(vii) β particles are more deflected by electric and magnetic field but in opposite direction.

Y radiations

(i) Y radiations a re electromagnetic radiations.

(ii) Y radiations have no charge.

(iii) Y radiations have no mass.

(iv) Velocity of Y radiation is equal to the velocity of light.

( v) Ionization power is least.

(vi)Y radiations have maximum penetration power. They are 100 times more penetrating than β particles.

(vii) Y radiations a re unaffected by electric and magnetic field.
Heavy nucleus undergo radioactivity because they are unstable.