In vs metallic element

In and metallic element both are nouns.

Word	Noun	Adjective	Verb	Adverb
In	Yes	No	No	No
metallic element	Yes	No	No	No

As nouns, metallic element is a hypernym of In; that is, metallic element is a word with a broader meaning than In:

In: a rare soft silvery metallic element; occurs in small quantities in sphalerite
metallic element: any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.

Other hypernyms of In include metal.

In (noun)	metallic element (noun)
a rare soft silvery metallic element; occurs in small quantities in sphalerite	any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.