Question

When a radioactive isotope undergoes Beta Decay, which of the following will NOT occur? Question 16 options: Energy is released. The atomic number of the original nucleus changes. The mass number of the original nucleus changes. The original nucleus approaches greater stability.

Answer 1

Answer:

This will not occur: The mass number of the original nucleus changes.

Explanation:

A radioactive isotope is an unstable isotope of an atom, which, ir order to attain stability, emits radtiation.

When an unstable isotope emits radition it is said that it has undergone decay.

There are three kinds of decay: Alpha, Beta and Gamma.

This question deals only with Beta decay.

The Beta decay consists in the emission of an electron (mass number zero, charge -1) as result of the transformation of neutron into a proton (mass number 1 and charge 0) and the so mentioned electron.

Since, the mass number is the sum of the number of protons and neutrons, the mass number of the original nucleus and the new nucleus are the same.

On the other hand, the atomic number (the number of protons) increase.

In summary:

• The mass number remains constant
• The atomic number incrreases
• The charge of the nucleus increases.

With that, you can review the four options of your question:

• Energy is released: Beta decay is a nuclear reaction, so it is accompanied by the release of energy. Hence, this is true.

• The atomic number of the original nucleus changes: True. This was stated in our analysis: as consequence of the creation of a proton, the atomic number increases.

• The mass number of the original nucleus changes. False. Since mass number is the sum of the numbrer of protons and neutrons, and one neutron originated a proton, the mass number does not change. Hence, this is the right answer choice.

• The original nucleus approaches greater stability. True. As stated, the decay of the nucleus originates a new more stable nucleus.