Ytterbium n. : A rare element of the boron group, sometimes associated with yttrium or other related elements, as in euxenite and gadolinite. Symbol Yb; provisional atomic weight 173.2. Cf. Yttrium.

Example:
How many protons, electrons, and neutrons does Ytterbium have?

Taxonomy
ytterbium, Yb, element, metal, rare earths, Isotopes of ytterbium, stable, compounds, element ytterbium, ytterbium monoxide, GPa, stable isotopes, ytterbia, Yb3, isotopes, lasers, aq, concentration.

Defination from the web:
... Ytterbium is a soft, malleable and rather ductile element that exhibits a bright silvery luster. ... Naturally occurring ytterbium is composed of 7 stable isotopes, Yb-168, Yb-170, Yb-171, Yb-172, ...