71Lu

Lutetium

Lanthanidesolidblock f

The last and densest lanthanide, grown into PET scanner crystals and used as a decay clock for dating meteorites and the Earth's early crust.

Atomic number	71
Standard atomic weight	174.97 g/mol ± 0.01
Group · period	f-block series · 6
Electron configuration	[Xe] 4f¹⁴ 5d¹ 6s²

About Lutetium

Lutetium is where the table argues with itself. Its configuration, [Xe] 4f¹⁴ 5d¹ 6s², is a filled f shell plus a d electron — which is a d-block configuration, and a strong body of opinion places lutetium in group 3 beneath yttrium rather than at the end of the lanthanides. It is kept with the lanthanides here for layout, but the case for moving it is serious and IUPAC has never fully closed the question. Lutetium's practical life is in lutetium oxyorthosilicate, the fast bright scintillator crystal in nearly every modern PET scanner, and in the Lu-Hf radiometric system, where lutetium-176's 37-billion-year half-life dates the oldest crust and the differentiation of the early Earth.

Use 174.97 g/mol in these solvers

Moles from Mass (n = m/M)

n = \frac{m}{M}

Opens with M = 174.97 g/mol already filled in

Gas Density from Molar Mass

\rho = \frac{PM}{RT}

Opens with M = 174.97 g/mol already filled in

Faraday's Law of Electrolysis (m = QM/nF)

m = \frac{Q M}{n F}

Opens with M = 174.97 g/mol already filled in

Ion Concentration as CaCO₃ Equivalent

C_{\mathrm{CaCO_3}} = C_{\mathrm{ion}} \times \frac{50.04}{\mathrm{EW}}

Opens with EW = 174.97 g/mol already filled in

Acid Feed to Reduce Alkalinity

\dot m = \frac{\Delta \mathrm{Alk} \, Q \times \frac{\mathrm{EW}}{50.04}}{p/100\%}

Opens with EW = 174.97 g/mol already filled in

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