Nothing happens because a physical change only changes the appearance of the substance, whereas a chemical change transforms the substance into something completely different.
i.e. (chemical change) wood + fire = ash
(physical change) wood + axe = smaller pieces of wood
BH3 VSEPR. Boron trihydride structure, BH3. On B, there are three bonded domains and no lone pairs, which give molecular geometries and trigonal planar electron-domain.
