Question

Many heavy nuclei are “alpha emitters”: they emit an alpha particle, which is the historical name for the nucleus of a helium atom, which contains two protons. For example, a thorium nucleus containing 90 protons is an alpha-emitter. What element does thorium turn into as a result of emitting an alpha particle?

Short answer

The element that thorium turns into as a result of emitting an alpha particle is $R{a}_{88}$.

Step-by-step solution

Identification of the given data

The given data is listed below as,

The alpha emitter is the thorium that contains about 90 protons.

Significance of the decay reaction

The decay reaction transforms an unstable nucleus to a stable nucleus by emitting radiation.

The concept of the decay reaction gives the element that thorium turns into due to the emission of alpha particles.

Determination of the element that thorium turns into due to the emission of alpha particles

As charge is conserved in decay, then the products of the decay reaction is as follows,

$T{h}_{90}\to X_a+{\alpha }_2$

As the thorium element has $+90e$amount of charge and as the alpha particle has $+2e$amount of charge, then,

$$\begin{gathered} 90=a+2 \\ a=88 \end{gathered}$$

As the resultant nuclei has an atomic number 88 which is radium, then the element is$R{a}_{88}$.

Thus, the element that thorium turns into as a result of emitting an alpha particle is $R{a}_{88}$.