What is the geometry of a BF3 molecule?

The molecule is 'trigonal planar'.This is because the central atom, boron, is attached to three fluorine atoms, and each fluorine atom repels the other fluorine atoms as much as possible. The only configuration that allows this to happen is for all atoms to be in the same plane and for the fluorine to form a triangle shape. The angle between the fluorine atoms is therefore 120 degrees.