5.1.2a Composition of the nucleus and isotopes

Plutonium-239 ( $94239Pu^{239}_{94}\text{Pu}$ ) is a radioactive isotope of plutonium that can be used in nuclear reactors.

Describe the composition and structure of a neutral atom of plutonium-239.

[4]

Another isotope of plutonium is plutonium-242. Describe how an atom of plutonium-242 differs from an atom of plutonium-239.

[1]

In a nuclear reactor, a nucleus of plutonium-239 absorbs a slow-moving neutron and then undergoes nuclear fission.

Three neutrons, a nucleus of barium-141 ( $56141Ba^{141}_{56}\text{Ba}$ ), and a nucleus of an element represented by $Y\text{Y}$ are produced.

Complete the equation for this fission reaction.

\text{n} + \,^{239}_{94}\text{Pu} \longrightarrow \,^{141}_{56}\text{Ba} + \dots\dots\text{Y} + 3\text{n}

[2]

Barium-141 ( $56141Ba^{141}_{56}\text{Ba}$ ) is radioactive. It decays by $β−\beta^-$ -emission to isotope $R\text{R}$ .

Determine:

the proton number of $R\text{R}$

[1]

the nucleon number of $R\text{R}$

[1]