Page 461 - Schaum's Outline of Theory and Problems of Applied Physics

446 NUCLEAR PHYSICS [CHAP. 36

Fig. 36-2. Radioactive decay.

responsible for beta decay, electron capture, and positron emission and in this way helps determine nuclear
structures.

SOLVED PROBLEM 36.10
What happens to the atomic number and mass number of a nucleus that (a) emits an electron, (b) undergoes
electron capture, (c) emits an alpha particle?
(a) Z increases by 1, A is unchanged, (b) Z decreases by 1, A is unchanged. (c) Z decreases by 2, A decreases
by 4.

SOLVED PROBLEM 36.11

How many successive alpha decays occur in the decay of the thorium isotope 228 Th into the lead isotope
90
212
82 Pb?
Each alpha decay means a reduction of 2 in atomic number and of 4 in mass number. Here Z decreases by 8
and A by 16, which means that 4 alpha particles are emitted.