Question

The only stable isotope of fluorine is fluorine-19. Predict possible modes of decay for fluorine-21, fluorine-18, and fluorine-17.

Short answer

For fluorine-17 and fluorine-18, the mode of decay is positron production or electron capture. For fluorine 21, the mode of decay is beta particle production.

Step-by-step solution

Modes of decay

Alpha decay, beta decay, positron decay, electron capture, and gamma decay are the five common modes of decay in nuclear chemistry.The type of decay in the reactions is predicted by observing the neutron-proton (N/Z) ratio.

Predicting the modes of decay for fluorine-17 and fluorine-18

We know that fluorine-17 and fluorine-18 have a low ratio of neutron to proton. To increase this ratio, we need to convert more protons into neutrons. So, the mode of decay to be used is positron production or electron capture.

The equations are:

$\begin{array}{l}{}_9{}^{17}\text{F}{\to }_8^{17}O{+}_{+1}^{0}e\\ {}_9{}^{18}\text{F}{\to }_8^{18}O{+}_{+1}^{0}e\end{array}$

Predicting the modes of decay for fluorine-21

We know that fluorine-21 has a high ratio of neutron to proton. To decrease this ratio, we need to convert more neutrons into protons. So, the mode of decay used is beta particle production.

The equation is:

${}_9{}^{21}\text{F}{\to }_{10}^{21}\text{Ne}{+}_{-1}^{0}e$