If the following element undergoes alpha decay, which element does it change into?

234/90Th

a
Uranium (U)
b
Francium (Fr)
c
Radium (Ra)
d
Radon (Rn)

1 answer

When an element undergoes alpha decay, it emits an alpha particle, which consists of 2 protons and 2 neutrons (essentially a helium nucleus).

For the given element \( \frac{234}{90}Th \) (Thorium-234), the atomic number decreases by 2 (since 2 protons are lost), and the mass number decreases by 4 (since 2 protons and 2 neutrons are lost).

Calculating the new atomic number and mass number:

  • New mass number = 234 - 4 = 230
  • New atomic number = 90 - 2 = 88

The element with atomic number 88 is Radium (Ra). Therefore, after undergoing alpha decay, Thorium-234 changes into Radium-230.

So, the correct answer is: c. Radium (Ra)