Yb vs ytterbium

Yb and ytterbium both are nouns.

Word	Noun	Adjective	Verb	Adverb
Yb	Yes	No	No	No
ytterbium	Yes	No	No	No

As nouns, Yb and ytterbium are synonyms defined as:

Yb and ytterbium: a soft silvery metallic element; a rare earth of the lanthanide series; it occurs in gadolinite and monazite and xenotime

Other synonyms of Yb include atomic number 70.

Yb (noun)	ytterbium (noun)
a unit of information equal to 1000 zettabits or 10^24 bits	a soft silvery metallic element; a rare earth of the lanthanide series; it occurs in gadolinite and monazite and xenotime
a soft silvery metallic element; a rare earth of the lanthanide series; it occurs in gadolinite and monazite and xenotime