A ́ = 60
Now balance the atomic numbers, taking into account that cobalt has 27 protons (you learn this by
consulting the periodic table) and that there is one more proton on the right-hand side:
By looking at the periodic table, one finds that Z’ = 28 is nickel:
Gamma Decay. Gamma decay is the emission of γ-rays, which are high-energy photons. They carry
no charge and simply lower the energy of the emitting (parent) nucleus without changing the mass
number or the atomic number. In other words, the daughter’s A is the same as the parent’s and the
daughter’s Z is the same as the parent’s.
BASIC CONCEPT
γ particles are high-energy photons. γ decay releases energy but does not change A or Z.The generic gamma decay reaction is thus:
where the asterisk on the parent nucleus designates that it is in an unstable, high-energy state.
Positron Emission. Positron emission occurs when a positively charged particle known as a positron
is emitted. A positron is most conveniently thought of (and often referred to) as an antielectron: It
has the same (negligible) mass but has a positive rather than a negative charge. The positron is