boom: any of various more-or-less horizontal spars or poles used to extend the foot of a sail or for handling cargo or in mooring
spar: a stout rounded pole of wood or metal used to support rigging
rutherford atom: first modern concept of atomic structure; all of the positive charge and most of the mass of the atom are contained in a compact nucleus; a number of electrons (equal to the atomic number) occupy the rest of the volume of the atom and neutralize the positive charge