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Lu

Lutetium

Lutetium is a chemical element with the symbol Lu and atomic number 71. It has a standard atomic weight of 174.97, sits in period 6 of the f-block, and is classified as a lanthanide.

Properties

SymbolLu
Atomic number71
Standard atomic weight174.97
CategoryLanthanide
Groupf-block — no group
Period6
Electron configuration[Xe] 4f14 5d1 6s2
Outer-shell electrons2

The figure of 174.97 is a standard atomic weight.

Calculate with lutetium

Atomic weights are the IUPAC 2021 standard values, abridged to the conventional five significant figures. Group, period, category and electron configuration are derived from the atomic number rather than stored, so they cannot drift out of step with it.