Lutetium
Lutetium is a hard, dense, silvery-white lanthanide, the last and heaviest element in its row of the periodic table. Identified in 1907 after a priority dispute between two chemists, it's named after Lutetia, the ancient name for Paris.
- Group · Period
- — · 6
- At room temp
- solid
- Melts at
- 1936 K
- Density
- 9.84 g/cm³
- Discovered
- 1907
Uses
Lutetium’s most important application today is in medical imaging: cerium-doped lutetium crystals are used as scintillators inside PET scanners, converting the radiation emitted by a patient’s tracer dose into light that the scanner’s detectors can measure. This use takes advantage of lutetium’s density and its ability to respond quickly and consistently to incoming radiation. Because pure lutetium is difficult and costly to extract from the other lanthanides it’s mixed with in nature, it’s used sparingly, and it doesn’t have the kind of large-scale industrial role that cheaper rare earths like cerium or lanthanum have.
History
Lutetium was identified in 1907, essentially simultaneously, by French chemist Georges Urbain and Austrian chemist Carl Auer von Welsbach, both of whom had separated a new element from samples of what chemists had been calling ytterbium. The two disagreed over naming rights, and it took several years of debate before the scientific community settled on Urbain’s proposed name, lutetium, after Lutetia, the old Roman name for Paris. As the last element in the lanthanide row, its discovery effectively closed out the decades-long effort to identify the full set of rare-earth elements.
Fun facts
- Lutetium is named after Lutetia, the Roman-era name for the city that became Paris.
- It was discovered independently by two chemists working in different countries at almost the same time, leading to a dispute over who deserved credit.
- Lutetium-based crystals are used inside PET scanners, the medical imaging devices used to detect cancer and study brain activity.
Frequently asked questions
What is lutetium used for?
Its most valuable modern use is inside PET (positron emission tomography) scanners, where crystals containing lutetium act as scintillators — materials that convert incoming radiation into flashes of light a detector can register. Because lutetium is rare and expensive to produce in pure form, it isn't used in the kind of bulk industrial applications common for some other lanthanides.
Why was there a dispute over who discovered lutetium?
In 1907, French chemist Georges Urbain and Austrian chemist Carl Auer von Welsbach both announced, within a short time of each other, that they had separated a new element out of what was thought to be pure ytterbium. Each claimed priority and proposed his own name, and it took years of debate among chemists before Urbain's name, lutetium, became the internationally accepted one.
Is lutetium a rare-earth element even though it's grouped with the transition metals in some tables?
Lutetium is classified as a lanthanide and is one of the rare-earth elements, even though its properties — being hard, dense, and having a filled inner electron shell — make it behave a bit more like the transition metals that follow it than like the earlier, more reactive lanthanides.
Compounds
3 notable compounds containing Lu
- Lu2SiO5industrial
Lutetium oxyorthosilicate
A dense synthetic crystal, usually grown with a small amount of cerium doping, that converts incoming gamma rays into flashes of visible light extremely quickly.
Used for: Scintillator crystal in PET scanner detectors
- LuCl3halide
Lutetium(III) chloride
A white, hygroscopic lutetium salt handled in the laboratory as its hydrate, serving as a common precursor for other lutetium compounds.
Used for: Laboratory precursor for lutetium metal and lutetium compounds
- Lu2O3oxide
Lutetium(III) oxide
A white, dense rare-earth oxide and the standard commercial form of lutetium, the heaviest and densest of the naturally occurring lanthanides.
Used for: Precursor for lutetium-based scintillator crystals used in medical imaging
Isotopes
40 known isotopes
Swipe to see all columns →
| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Lu-175 stable | 97.401% | Stable | — | -55,165.68 keV | 8,069.14 keV | — |
| Lu-176 | 2.599% | 3.76E+10 Y | Beta-minus decay (100%) | -53,382.33 keV | 8,059.02 keV | 3.85 × 10-34 eV |
Show all 40 isotopes
| Lu-149 | — | 0.45 us | Proton emission (100%) | — | — | 1.01 × 10-9 eV |
| Lu-150 | — | 45 ms | Proton emission (70.9%), Electron capture / beta-plus decay (29.1%) | -24,771 keV | 7,866 keV | 1.01 × 10-14 eV |
| Lu-151 | — | 80.6 ms | Proton emission (63.4%), Electron capture / beta-plus decay (36.6%) | -30,300 keV | 7,904 keV | 5.66 × 10-15 eV |
| Lu-152 | — | 0.7 s | Electron capture / beta-plus decay (100%), Beta-plus, proton emission (15%) | -33,422 keV | 7,926 keV | 6.52 × 10-16 eV |
| Lu-153 | — | 0.9 s | Alpha decay, Electron capture / beta-plus decay | -38,375.46 keV | 7,959.09 keV | 5.07 × 10-16 eV |
| Lu-154 | — | — | Unknown | -39,667 keV | 7,968 keV | — |
| Lu-155 | — | 68 ms | Alpha decay (90%), Electron capture / beta-plus decay (10%) | -42,545.06 keV | 7,987.44 keV | 6.71 × 10-15 eV |
| Lu-156 | — | 494 ms | Alpha decay (95%), Electron capture / beta-plus decay (5%) | -43,699.55 keV | 7,995.38 keV | 9.24 × 10-16 eV |
| Lu-157 | — | 6.8 s | Alpha decay (0%) | -46,439.82 keV | 8,013.31 keV | 6.71 × 10-17 eV |
| Lu-158 | — | 10.6 s | Electron capture / beta-plus decay (99.09%), Alpha decay (0.91%) | -47,212.2 keV | 8,018.57 keV | 4.30 × 10-17 eV |
| Lu-159 | — | 12.1 s | Electron capture / beta-plus decay (100%), Alpha decay (0.1%) | -49,708.61 keV | 8,034.6 keV | 3.77 × 10-17 eV |
| Lu-160 | — | 36.1 s | Electron capture / beta-plus decay (100%), Alpha decay (0.0001%) | -50,269.94 keV | 8,038.34 keV | 1.26 × 10-17 eV |
| Lu-161 | — | 77 s | Electron capture / beta-plus decay (100%) | -52,562.35 keV | 8,052.78 keV | 5.93 × 10-18 eV |
| Lu-162 | — | 1.37 m | Electron capture / beta-plus decay (100%) | -52,831.76 keV | 8,054.56 keV | 5.55 × 10-18 eV |
| Lu-163 | — | 3.97 m | Electron capture / beta-plus decay (100%) | -54,791.42 keV | 8,066.68 keV | 1.92 × 10-18 eV |
| Lu-164 | — | 3.14 m | Electron capture / beta-plus decay (100%) | -54,642.38 keV | 8,065.8 keV | 2.42 × 10-18 eV |
| Lu-165 | — | 10.74 m | Electron capture / beta-plus decay (100%) | -56,442.25 keV | 8,076.75 keV | 7.08 × 10-19 eV |
| Lu-166 | — | 2.65 m | Electron capture / beta-plus decay (100%) | -56,020.99 keV | 8,074.18 keV | 2.87 × 10-18 eV |
| Lu-167 | — | 51.5 m | Electron capture / beta-plus decay (100%) | -57,526.28 keV | 8,083.17 keV | 1.48 × 10-19 eV |
| Lu-168 | — | 5.5 m | Electron capture / beta-plus decay (100%) | -57,072.83 keV | 8,080.4 keV | 1.38 × 10-18 eV |
| Lu-169 | — | 34.06 h | Electron capture / beta-plus decay (100%) | -58,082.53 keV | 8,086.32 keV | 3.72 × 10-21 eV |
| Lu-170 | — | 2.012 d | Electron capture / beta-plus decay (100%) | -57,306.23 keV | 8,081.67 keV | 2.62 × 10-21 eV |
| Lu-171 | — | 8.247 d | Electron capture / beta-plus decay (100%) | -57,828.47 keV | 8,084.66 keV | 6.40 × 10-22 eV |
| Lu-172 | — | 6.70 d | Electron capture / beta-plus decay (100%) | -56,736.08 keV | 8,078.23 keV | 7.88 × 10-22 eV |
| Lu-173 | — | 1.37 Y | Electron capture (100%) | -56,881.01 keV | 8,079.03 keV | 1.06 × 10-23 eV |
| Lu-174 | — | 3.31 Y | Electron capture / beta-plus decay (100%) | -55,570.29 keV | 8,071.45 keV | 4.37 × 10-24 eV |
| Lu-177 | — | 6.6443 d | Beta-minus decay (100%) | -52,383.9 keV | 8,053.45 keV | 7.95 × 10-22 eV |
| Lu-178 | — | 28.4 m | Beta-minus decay (100%) | -50,337.88 keV | 8,042.06 keV | 2.68 × 10-19 eV |
| Lu-179 | — | 4.59 h | Beta-minus decay (100%) | -49,059.01 keV | 8,035.07 keV | 2.76 × 10-20 eV |
| Lu-180 | — | 5.7 m | Beta-minus decay (100%) | -46,676.48 keV | 8,022.04 keV | 1.33 × 10-18 eV |
| Lu-181 | — | 3.5 m | Beta-minus decay (100%) | -44,797.41 keV | 8,011.93 keV | 2.17 × 10-18 eV |
| Lu-182 | — | 2.0 m | Beta-minus decay (100%) | -41,770 keV | 7,996 keV | 3.80 × 10-18 eV |
| Lu-183 | — | 58 s | Beta-minus decay (100%) | -39,716.11 keV | 7,984.81 keV | 7.87 × 10-18 eV |
| Lu-184 | — | 19 s | Beta-minus decay (100%) | -36,300 keV | 7,967 keV | 2.40 × 10-17 eV |
| Lu-185 | — | 160 ns | Beta-minus decay | -33,960 keV | 7,955 keV | 2.85 × 10-9 eV |
| Lu-186 | — | — | Beta-minus decay (100%) | -30,320 keV | 7,936 keV | — |
| Lu-187 | — | — | Beta-minus decay (100%), Beta-minus, neutron emission | -27,770 keV | 7,923 keV | — |
| Lu-188 | — | — | Beta-minus decay (100%) | -23,820 keV | 7,903 keV | — |