The ungrouped elements are the Rare Earth Elements or Metals, which currently lack a group number. Group numbers were originally designed by the IUPAC. They go from 1 to 18. The rare earth metals are left out because they have too similar chemical properties and grouping is unnecessary. de;Metalle der Seltenen Erden Categories: Stub | Chemical element groups ... The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. ...

These elements include: Lanthanum, Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium and Ytterbium of the Lanthanides; and Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium and Lawrencium of the Actinides. General Name, Symbol, Number Lanthanum, La, 57 Chemical series Lanthanides Group, Period, Block 3 , 6, f Density, Hardness 6146 kg/m3, 2. ... General Name, Symbol, Number Cerium, Ce, 58 Chemical series Lanthanides Group, Period, Block _ , 6, d Density, Hardness 6689 kg/m3, 2. ... General Name, Symbol, Number Praseodymium, Pr, 59 Chemical series Lanthanides Group, Period, Block _ , 6 , f Density, Hardness 6640 kg/m3, no data Appearance silvery white, yellowish tinge Atomic properties Atomic weight 140. ... General Name, Symbol, Number Neodymium, Nd, 60 Chemical series Lanthanides Group, Period, Block _ , 6, f Density, Hardness 6800 kg/m3, no data Appearance silvery white, yellowish tinge Atomic properties Atomic weight 144. ... General Name, Symbol, Number Promethium, Pm, 61 Chemical series Lanthanides Group, Period, Block _ , 6, f Density, Hardness 7264 kg/m3, no data Appearance metallic Atomic properties Atomic weight 145 u Atomic radius (calc. ... General Name, Symbol, Number Samarium, Sm, 62 Chemical series Lanthanides Group, Period, Block _ , 6 , f Density, Hardness 7353 kg/m3, no data Appearance silvery white Atomic properties Atomic weight 150. ... General Name, Symbol, Number Europium, Eu, 63 Chemical series Lanthanides Group, Period, Block _, 6, f Density, Hardness 5244 kg/m3, no data Appearance silvery white Atomic properties Atomic weight 151. ... General Name, Symbol, Number gadolinium, Gd, 64 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery white Atomic mass 157. ... General Name, Symbol, Number Terbium, Tb, 65 Chemical series Lanthanides Period, Block 6, f Density, Hardness 8219 kg/m3, no data Appearance silvery white Atomic properties Atomic weight 158. ... General Name, Symbol, Number Dysprosium, Dy, 66 Chemical series Lanthanides Group, Period, Block _ , 6 , f Density, Hardness 8551 kg/m3, no data Appearance silvery white Atomic properties Atomic weight 162. ... General Name, Symbol, Number Holmium, Ho, 67 Chemical series Lanthanides Group, Period, Block NA, 6, f Density, Hardness 8800 kg/m3, ND Appearance silvery white Atomic properties Atomic weight 164. ... General Name, Symbol, Number Erbium, Er, 68 Chemical series Lanthanides Group, Period, Block NA, 6, f Density, Hardness 9066 kg/m3, ND Appearance silvery white Atomic properties Atomic weight 167. ... General Name, Symbol, Number Thulium, Tm, 69 Chemical series Lanthanides Group, Period, Block NA, 6, f Density, Hardness 9321 kg/m3, no data Appearance silvery gray Atomic properties Atomic weight 168. ... General Name, Symbol, Number Ytterbium, Yb, 70 Chemical series Lanthanides Group, Period, Block NA, 6, f Density, Hardness 6570 kg/m3, ND Appearance silvery white Atomic properties Atomic weight 173. ... The lanthanide series is the 14 rare earth chemical elements which lie between lanthanum and ytterbium on the periodic table. ... General Name, Symbol, Number actinium, Ac, 89 Chemical series Actinides Group, Period, Block 3 , 7, f Density, Hardness 10070 kg/m3, n/a Appearance silvery Atomic properties Atomic weight (227) u Atomic radius (calc. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Transition metals Period, Block 7, f Density, Hardness 11724 kg/m3, 3. ... General Name, Symbol, Number protactinium, Pa, 91 Chemical series Transition metals Group, Period, Block _ , 7, f Density, Hardness 15370 kg/m3, no data Appearance bright, silvery metallic luster Atomic properties Atomic weight 231. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery gray metallic Atomic mass 238. ... General Name, Symbol, Number Neptunium, Np, 93 Chemical series Actinides Period, Block 7, f Density, Hardness 20250 kg/m3, n/a Appearance Silvery metallic Atomic properties Atomic weight [237] u Atomic radius (calc. ... General Name, Symbol, Number Plutonium, Pu, 94 Chemical series Actinides Period, Block 7, f Density, Hardness 19816 kg/m3, no data Appearance silvery white metal Atomic properties Atomic weight 244. ... General Name, Symbol, Number americium, Am, 95 Chemical series actinides Group, Period, Block 7, f Appearance silvery white Atomic properties Atomic weight [243] amu Atomic radius (calc. ... General Name, Symbol, Number curium, Cm, 96 Chemical series actinides Period, Block 7 , f Appearance silvery Atomic properties Atomic weight [247] amu Atomic radius (calc. ... Known properties Name, Symbol, Number Berkelium, Bk, 97 Chemical series Actinides Period, Block 7, f Appearance unknown; probably metallic, silvery white or gray Atomic weight [247] amu Electron configuration [Rn] 5f9 7s2 e- s per energy level 2,8,18,32,27,8,2 State of matter solid Density 14780... Known properties Name, Symbol, Number Californium, Cf, 98 Chemical series Actinides Period, Block 7, f Appearance unknown; probably metallic, silvery white or gray Atomic weight [251] amu Electron configuration [Rn]5f107s2 e-s per energy level 2,8,18,32,28,8,2 State of matter solid Most stable isotopes... Known properties Name, Symbol, Number Einsteinium, Es, 99 Chemical series Actinides Period, Block 7 , f Appearance unknown; probably metallic, silvery white or gray Atomic weight [252] amu Electron configuration probably [Rn]5f11 7s2 e- s per energy level 2, 8, 18, 32, 29, 8, 2 State of matter Solid Most... Known properties Name, Symbol, Number Fermium, Fm, 100 Chemical series Actinides Period, Block 7, f Appearance unknown; probably metallic, silvery white or gray Atomic weight [257] amu Electron configuration [Rn]5f12 7s2 e-s per energy level 2, 8, 18, 32, 30, 8, 2 State of matter Presumably a solid... Known properties Name, Symbol, Number Mendelevium, Md, 101 Chemical series Actinides Period, Block 7 , f Appearance unknown; probably metallic, silvery white or gray Atomic weight [258] amu Electron configuration [Rn]5f13 7s2 e- s per energy level 2, 8, 18, 32, 31, 8, 2 State of matter Presumably a solid... Known properties Name, Symbol, Number Nobelium, No, 102 Chemical series Actinides Period, Block 7, f Appearance unknown Atomic weight [259] u Electron configuration [Rn] 5f14 7s2 e- s per energy level 2, 8, 18, 32, 32, 8, 2 State of matter Presumably a solid Most stable isotopes Nobelium, also known... Known properties Name, Symbol, Number lawrencium, Lr, 103 Chemical series Transition metals Group, Period, Block 3, 7, d Appearance unknown; probably metallic, silvery white or gray Atomic weight [ 262 ] amu Electron configuration probably [Rn]5f14 6d1 7s2 e- s per energy level 2, 8, 18, 32, 32, 9, 2 State... The actinide series encompasses the 14 chemical elements that lie between actinium and nobelium on the periodic table with atomic numbers 89 - 102 inclusive. ...