Install gcu-plugin by entering the following commands in the terminal:
sudo apt update sudo apt install gcu-plugin
Description:
GNOME chemistry utils (browser plugin)
The GNOME Chemistry Utils provide C++ classes and Gtk+-2 widgets related to chemistry. They will be used in future versions of both gcrystal and gchempaint. . This package provides a browser plugin for Gecko-based browsers. It does not (yet) work with WebKit-based browsers.
Homepage: http://www.nongnu.org/gchemutils/
Version: 0.14.17-1ubuntu1
Section: universe/science