Question

Hafnium (Hf), with a mass number of 174 and an atomic number of 72, decays by emission of an alpha particle. Identify the product of the nuclear reaction by providing its atomic symbol, mass number , and atomic number.

Answer 1

Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into an atom with a mass number that is reduced by four and an atomic number that is reduced by two. An alpha particle is identical to the nucleus of a helium-4 atom, which consists of twoprotons and two neutrons

¹⁷⁴₇₂Hf → ¹⁷⁰₇₀X + ⁴₂α

Then we find in a periodic table who X represents. It should have a mass number of 170 and an atomic number of 70.

Then we find that the Ytterbium-170 (isotope) will fix in our X. Thus

¹⁷⁴₇₂Hf → ¹⁷⁰₇₀Tb + ⁴₂α