# How many neutrons are found in an isotope of F (Flourine)?

For ""^19F there are 10 neutrons......
The ""^19F is almost 100% abundant. Because in each fluorine nucleus, there are necessarily $\text{9 protons}$, why necessarily?, there must be 10 neutrons, neutral massive particles, in the fluorine nucleus.
Note that ""^19F is 100% spin active $\left(\text{I=1/2}\right)$, it can be regularly used in $\text{NMR spectroscopy}$. Because fluorine chemistry is a trifle hazardous, this spectroscopy is not as well developed as that of ""^1H or ""^13C.