Answer
$GaF_{3}$
Gallium (III) fluoride
Work Step by Step
Atoms of elements want to have the electron configuration of the nearest noble gas (in terms of number of electrons) on the periodic table. The nearest noble gas to Flourine is Neon, so a Fluorine ion will gain an electron to gain this electron configuration, thus giving each Fluorine ion a charge of -1. Gallium, however, must lose three electrons in order to get the electron configuration of its nearest noble gas, Argon. When a compound is formed between these two elements, the overall charge must be neutral. Because the overall charge of a Gallium ion is +3, there must be three Fluorine ions, which have a charge of -1, to cancel out this charge. Putting this together, the formula for the resulting compound is $GaF_{3}$.
