Yes, Thomas Chapman is on the 1820 Gibson County, Indiana Census.
I did not find him on the 1830 Gibson County, IN Census
I suspect he is related to the Thomas S.Grissom on the same page.. Thomas S.Grissom is the son ofJohn West Grissom and Mary Chapman.
If this doesn't run together this is the names of the people on the same Census page:I do see family clusters a lot.
1820 Gibson Co., IN Census Robert Stockwell Ephram Darnel/Parnel JohnW.?King Samuel King William Coughorn Timothy Mayhall William Mayhall Eli Strain Solomon D. King David King Stephen Fisher Thomas S.Grissom Wm Robertson John Woods George Shafer JamesAkens/A Kens Thomas Chapman Samuel Woods Joseph Woods Feret? Fitzjerel Samuel Wortts? Joseph Whitsitt Adam Harper Edward Moor Thomas Souden/Louden