Atom center of mass, although strictly speaking these particles are believed to be point-like and cannot be said to be rotating. Spin is measured in units of the reduced Planck constant (ħ), with electrons, protons and neutrons all having spin ½ ħ, or "spin-½". In an atom, electrons in motion around the nucleus possess orbital angular momentum in addition to their spin, while the nucleus itself possesses angular momentum due to its nuclear spin. The magnetic field produced by an atom—its magnetic moment—is determined by these various forms of angular momentum, just as a rotating charged object classically produces a magnetic
Hot atom Hot atom In physical chemistry, a hot atom is an atom that has a high kinetic or internal energy. When molecule AB adsorbs on a surface dissociatively, In case 2, B gains a high translational energy from the adsorption energy of A, and hot atom B is generated. For example, the hydrogen molecule, because of its light mass, gets a high translational energy. Such a hot atom does not fly into vacuum but is trapped on the surface, where it diffuses with high energy. Hot atoms are expected to play important roles in catalytic reactions. For example, a reaction of