calcium ion vs calcium

calcium ion and calcium both are nouns.

Word	Noun	Adjective	Verb	Adverb
calcium ion	Yes	No	No	No
calcium	Yes	No	No	No

As nouns, calcium is a hypernym of calcium ion; that is, calcium is a word with a broader meaning than calcium ion:

calcium ion: ion of calcium; a factor in the clotting of blood
calcium: a white metallic element that burns with a brilliant light; the fifth most abundant element in the earth's crust; an important component of most plants and animals

Other hypernyms of calcium ion include atomic number 20, Ca, clotting factor, coagulation factor.

calcium ion (noun)	calcium (noun)
ion of calcium; a factor in the clotting of blood	a white metallic element that burns with a brilliant light; the fifth most abundant element in the earth's crust; an important component of most plants and animals