Carbon, C, P Block, 2, 6, 12.0107u. 6 protons, 6 electrons, 6 neutrons
Helium, He, S Block, 1, 2, 4.0026u, 2 protons, 2 electrons, 2 neutrons
Germanium, Ge, P Block, 4, 32, 72.64u, 32 protons, 32 electrons, 41 neutrons
Oxygen, O, P Block, 2, 8, 16u, 8 protons, 8 electrons, 8 neutrons
Scandium, Sc, D Block, 4, 21, 44.9559u, 21 protons, 21 electrons, 24 neutrons
Tellurium, Te, P Block, 5, 52, 127.60u, 52 protons, 52 electrons, 76 neutrons
Hydrogen, H, S Block, 1, 1, 1.008u, 1 proton, 1 electron, 0 neutrons
Iron, Fe, D Block, 4, 26, 55.845u, 26 protons, 26 electrons, 30 neutrons
Beryllium, Be, S Block, 2, 4, 9.012u, 4 protons, 4 electrons, 5 neutrons
Vanadium, V, D Block, 4, 23, 50.942u, 23 protons, 23 electrons, 28 neutrons
Silver, Ag, D Block, 5, 47, 108u, 47 protons, 47 electrons, 61 neutrons
Gallium, Ga, P Block, 4, 31, 69.723u, 31 protons, 31 electrons, 39 neutrons
Bromine, Br, P Block, 4, 35, 79.904u, 35 protons, 35 electrons, 45 neutrons
Fluorine, F, P Block, 2, 9, 18.998u, 9 protons, 9 electrons, 10 neutrons
Manganese, Mn, D Block, 4, 25, 54.938u, 25 protons, 25 electrons, 30 neutrons
Strontium, Sr, S Block, 5, 38, 87.62u, 38 protons, 38 electrons, 50 neutrons
Francium, Fr, S Block, 7, 87, 223u, 87 protons, 87 electrons, 136 neutrons
and any get of units that has those units in the proper place can be considered a density unit. The ones that has those specifically are A, B, E and F