mourning vs sorrowful

mourning is a noun but sorrowful is not a noun.

Word	Noun	Adjective	Verb	Adverb
mourning	Yes	Yes	No	No
sorrowful	No	Yes	No	No

mourning (noun)	sorrowful (noun)
the passionate and demonstrative activity of expressing grief
state of sorrow over the death or departure of a loved one

mourning (adjective)	sorrowful (adjective)
sorrowful through loss or deprivation	experiencing or marked by or expressing sorrow especially that associated with irreparable loss