Question

What is the change in atomic mass number when an atom emits an alpha particle?

Answer 1

Answer:

Decreases by 4

Explanation:

• An alpha particle is made of two protons and two neutrons. An alpha decay involves the ejection of an alpha particle from the nucleus.
• Therefore since an alpha particles is equivalent to a helium nucleus, it involves the loss of 2 protons and 2 neutrons.
• Hence, we can conclude that when a nucleus emits an alpha particle, the mass number or the atomic mass decreases by 4 and the atomic number decreases by 2.