Chemical structures editor

 BKchem is a free chemical drawing program, which is written in Python.
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 Some of the features, you can expect:
  * Drawing (bond-by-bond drawing; templates for common rings; expanding of
    common-groups; draws radicals, charges, arrows; color support ...)
  * Editing (unlimited undo and redo capabilities; aligning; scaling;
    rotation (2D, 3D) ...)
  * Export/Import (fully supported SVG-, OpenOffice.org-Draw-, EPS-export;
    basic support for CML1 and CML2 import and export)