Chemik!

Marvin is a great alternative to the subscription based ChemDraw by CambridgeSoft. It is a collection of tools for drawing, displaying and characterizing chemical structures, substructures and reactions.It will also convert structures you create to various molecular visualiztion formats, such as .pdb and .mol, compatible with programs such as PyMOL and SwissPDB Viewer.

ACD/ChemSketch is a chemically intelligent drawing interface that allows you to draw almost any chemical structure including organics, organometallics, polymers, and Markush structures. Use it to produce professional looking structures and diagrams for reports and publications.

Avogadro is a free, fantastically easy to use molecule editor.

The Gnome Chemistry Utils include six chemistry related programs: - GChemPaint, a 2D chemical formula editor. - a chemical calculator (computes raw formule, molar weight, mass composition and isotopic pattern). - a molecule 3d viewer using OpenGL to display molecular models. - a crystal structure editor and viewer. - a periodic table of the elements. - a spectrum viewer.

BKChem is a free (as in free software :o) chemical drawing program. It was conceived and written by Beda Kosata and is currently maintained by Reinis Danne.

Kalzium (German for: Calcium) is a periodic table of the elements for KDE SC 4.It contains information about 103 chemical elements, including mass, charge, picture, discovery information, chemical and energy data, and a model of the atom. The table itself can be configured to display numeration, state of matter, and colour-coding in various ways. Additionally, a date index is available, allowing only elements discovered up to a defined year to be shown.

A Periodic Table of Elements that contains more than 25 scientific truths about each element including density, state, atomic radius, etc.. Can be translated into 8 languages.

What's your favorite molecule? With ChemJuice, chemical structure drawing is now at your fingertips.

Communicate with the natural language of chemical structures, biological pathways, and models