1/3 🧵 Deuterium is the atom. Deuteron is the nucleus inside that atom. Same family, different level of zoom.

2/3 🧵 A deuterium atom has 1 proton + 1 neutron in its nucleus, plus 1 electron orbiting around it. Strip off that electron and what’s left is the deuteron: just the bare nucleus. Chemists care about deuterium as an isotope of hydrogen; nuclear physicists care about the deuteron because that’s the part that would participate in fusion.

3/3 🧵 In an electrolysis setup, people often say “deuterons move toward the cathode” because in the liquid you’re dealing with positively charged deuterium species heading toward the negative electrode. But once you’re talking about the neutral atom with its electron included, that’s deuterium. Tiny wording difference, huge difference in what’s actually moving around.