Question

An atom that has 84 protons and 86 neutrons undergoes a reaction. At the end of the reaction, it has 82 protons and 84 neutrons. What happened to the atom?

Answer 1

Answer: The atom undergoes alpha decay.

Explanation: An atom has 84 protons and 86 neutrons initially. When this atom undergoes a reaction the product obtained has 82 protons and 84 neutrons.

As the product obtained has 2 protons less and 2 neutrons less which means that the mass number is decreased by 4 units and atomic number is reduced by 2 units.

The atom undergoes an alpha-decay because in this decay the particle emitted is alpha particle which has an atomic number of 2 and atomic mass of 4 units.

Equation follows:

$_{84}^{170}\textrm{X}\rightarrow _{82}^{166}\textrm{Y}+_2^4\alpha$

The atom which is undergoing alpha decay is Polonium (Po) and the product formed is Lead (Pb).

Answer 2

Hi! the atom in this particular problem has emitted an alpha particle in a nuclear reaction. 

Glad I could help, and happy learning!