chemtool binary package in Ubuntu Focal amd64

 Chemtool is a GTK+ based 2D chemical structure editor for X11. It
 supports many bond styles, most forms of text needed for chemical
 typesetting and splines/arcs/curved arrows.
 .
 Drawings can be exported to MOL and PDB format, SVG or XFig format for
 further annotation, as a PiCTeX drawing, as a bitmap or as Postscript
 files (several of these through XFig's companion program fig2dev).
 .
 The package also contains a helper program, cht, to calculate sum
 formula and (exact) molecular weight from a chemtool drawing file. Cht
 can either be called directly by Chemtool or on the console.

Source package