IB Physics SL E.3.7 Nuclear Changes in Decay

Practise predicting how proton number, neutron number and nucleon number change in alpha, beta-minus, beta-plus and gamma decay before identifying the daughter nuclide.

Exam points

apply A - 4 and Z - 2 for alpha emission and identify the helium nucleus
apply unchanged A with Z + 1 for β⁻ or Z - 1 for β⁺ decay when finding daughter nuclei
keep A and Z unchanged for gamma emission while recognizing nuclear de-excitation

[Maximum number: 3]

Thallium-205 $\left({ }_{81}^{205} \mathrm{Tl}\right)$ can also form from successive alpha ( $\alpha$ ) and beta-minus ( $\beta^{-}$ ) decays of an unstable nuclide. The decays follow the sequence $\alpha \beta^{-} \beta^{-} \alpha$ . The diagram shows the position of $\frac{205}{81} \mathrm{Tl}$ on a chart of neutron number against proton number.

Figure for Question E.3.7—Decay nuclear changes question 1 — IB Physics SL

Draw four arrows to show the sequence of changes to N and Z that occur as the ${ }_{81}^{205} \mathrm{Tl}$ forms from the unstable nuclide.

any $\alpha$ change correct

any $\beta$ change correct

diagram fully correct

Award [2 max] for a correct diagram without arrows drawn.

For MP1 accept a (-2, -2) line with direction indicated, drawn at any position in the graph.

For MP2 accept a (1, -1) line with direction indicated, drawn at any position in the graph.

Award [1] max for a correct diagram with all arrows in the opposite direction

All question bank results loaded

E.3.7—Decay nuclear changes question 1