Ytterbium is a soft, silvery lanthanide. It is fairly reactive, can exist in +2 and +3 states, and is widely used as a dopant in fiber and solid-state lasers.
The electron configuration of ytterbium is [Xe] 4f14 6s2. In its most common oxidation state (+3), ytterbium loses two 6s electrons and one 4f electron, forming a 4f13 configuration (Yb3+). In the +2 state (Yb2+), the 4f shell remains completely filled.
Ytterbium exhibits two oxidation states: +3 (most common) and +2 (less common but stable in some solids). The +3 state occurs in compounds like Yb2O3 and YbCl3, while the +2 state is found in YbI2 and YbF2. The stability of Yb2+ arises from the closed-shell 4f14 configuration.
Key applications of ytterbium include:
Ytterbium ions (Yb3+) have a simple energy-level structure, offering high efficiency, low quantum defect, and broad emission around 1030–1100 nm. These properties make Yb-doped lasers suitable for high-power applications with excellent beam quality.
Ytterbium is a moderately reactive metal. It tarnishes slowly in air and reacts with water to form ytterbium hydroxide and hydrogen gas:
\(\mathrm{2\,Yb(s) + 6\,H_2O(l) \rightarrow 2\,Yb(OH)_3(s) + 3\,H_2(g)}\)
It also reacts readily with halogens to form trihalides such as YbCl3 and YbBr3.
Ytterbium is paramagnetic in its +3 state due to the presence of an unpaired 4f electron. However, in the +2 state (4f14), it is diamagnetic because the 4f shell is completely filled, resulting in no unpaired electrons.
Important compounds include:
Ytterbium atoms are used in optical lattice clocks, where laser-cooled Yb atoms are trapped in an optical lattice and probed with ultra-stable lasers. The narrow linewidth of certain Yb transitions enables unprecedented timing precision, surpassing traditional cesium-based clocks.
Natural ytterbium consists of stable isotopes and is not radioactive. It is considered to have low toxicity, but fine powders may cause irritation if inhaled or ingested. Standard laboratory safety precautions should be followed when handling Yb compounds.
When ytterbium reacts with oxygen, it forms ytterbium(III) oxide:
\(\mathrm{4\,Yb(s) + 3\,O_2(g) \rightarrow 2\,Yb_2O_3(s)}\)
This oxide is stable and forms a protective layer on the metal surface, preventing further oxidation.