Question

What is Y? 222/86 Rn A/z + 4/2He

Answer 1

$^{222}_{\phantom{2}86}\text{Rn} \to ^{218}_{\phantom{2}84}\text{Po}+ ^{4}_{2}\text{He}$

Y is Po-218.

• A = 218
• Z = 84.

Explanation

$^{222}_{\phantom{2}86}\text{Rn} \to ^{A}_{Z}\text{Y}+ ^{4}_{2}\text{He}$

Here's the symbol of a particle in a nuclear reaction. $^{A}_{Z}\text{Y}$.

A stands for mass number. Z stands for atomic number. Both numbers shall conserve in a nuclear reaction.

• The mass number on the left hand side is 222.
• The two mass numbers on the right hand side add up to A + 4.
• 222 = A + 4.
• A = 218

So is the case for the atomic number. Try figure out the atomic number of Y using the same approach.

• The atomic number on the left hand side is 86.
• The two atomic number on the right hand side add up to __ + __.
• 86 = __ + __.
• Z = 84.

What element is Y? The atomic number of Y is 84. Refer to a periodic table. Element 84 corresponds to Po (polonium). Y is Polonium-218. The symbol of Y should be written as $^{218}_{\phantom{2}84}\text{Po}$. Hence the equation:

$^{222}_{\phantom{2}86}\text{Rn} \to ^{218}_{\phantom{2}84}\text{Po}+ ^{4}_{2}\text{He}$.