Question

How does electron deficient compound $BF_{3}$ achieve electronic saturation, i. e., fully occupied outer electron shells?

Answer 1

i)        To attain stability all atoms, need filled outer shell i.e. outer shell is filled with 8 electrons

ii)        We know that boron has only 3 electrons in its outermost shell and fluorine has only 7 electrons in its outermost shell

iii)        The three-excess electron in the boron paired with three fluorine atoms to form $BF_{3}$. Now we have 3 electron pairs (6 electrons); but what we need is 4 electron pairs (8 electrons) to attain stable state. so, there is the deficient of electrons

iv)        Finally, boron always in nature have an affinity for two more electrons preferably lone pair of some other atom