For the following nuclear decay series segment,

\(_{90}^{234}{Th}\) → → → \(_{90}^{230}{Th}\)

the overall emitted particles are

Concept:

Nuclear reaction:

• A nuclear reaction is a process in which two nuclei or more nuclei and other external subatomic particles collide with each other and form one or more new nuclei. 

Explanation:

For the nuclear reaction,

\(_{90}^{234}{Th}\) → → → \(_{90}^{230}{Th}\)

• α (alpha) particle is a positively charged particle with 2 protons and 2 neutrons. It is represented as 2He4 or 2α4. Removal of an α (alpha) particle will decrease the atomic number by 2 units while the mass number will be decreased by 4 units.
• β (beta) particle is negatively charged. It is represented as -1e0. Removal of a β (beta) particle will increase the atomic number by 1 unit while the mass number remains unchanged.
• The reaction can be represented as

90Th234 → 92U234 + 2 -1e0 → 90Th230

• When 90Th234 changes to 92U234, the mass number remains the same, and the atomic number increases by 2 units as β (beta) particles does not have any mass number.
• Now, the number of α particles lost when 92U234 changes to 90Th230 is 1.
• After the removal of one 2α4 particles, the atomic number will be

= 92 - 1 × 2 = 90

​= 234 - 4 = 230

which satisfies the nuclear reaction,

90Th234 → 92U234 + 2 -1e0 → 90Th230

​Conclusion:

Hence, for the nuclear reaction

\(_{90}^{234}{Th}\) → → → \(_{90}^{230}{Th}\) the overall emitted particles are two β and one α.