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Molkit

Net Dipole

Molkit can draw a molecule’s net dipole as an arrow over the structure. The arrow points toward the negative end of the molecule and carries a small plus mark at the positive end, the usual textbook convention. It is computed from the molecule’s geometry and bond polarities, so it is meant as a teaching aid for direction and relative strength rather than a precise measured moment.

Turning it on

Select a single, complete molecule. The Object Properties panel then shows a MOLECULE section with a Show net dipole (μ) checkbox. Tick it to draw the arrow.

The checkbox only appears for a whole covalent molecule. A partial selection, or a selection spanning more than one molecule, hides it, because a net dipole is a property of the molecule as a whole.

Reading the arrow

The arrow runs from the positive end of the molecule to the negative end, with the arrowhead at the negative end and a plus crossbar near the tail. For a molecule whose bond dipoles cancel, such as carbon dioxide or carbon tetrachloride, there is no meaningful direction to draw, so the overlay shows a small μ ≈ 0 marker instead of an arrow.

The direction is reliable for common teaching cases. The length reflects relative strength, not an absolute value in debye, so use it to compare or to show which way a molecule is polarized rather than to read off a number. The arrow sits in the molecule’s own layer, so it travels with the structure when you move it.

Adjusting it

With the dipole shown, the same MOLECULE section offers:

  • Color: a color swatch with transparency, plus a reset button.
  • Head size: a slider for the arrowhead scale.
  • Thickness: a slider for the stem width.
  • Position: a reset button. You can drag the arrow to reposition it over the molecule, and reset returns it to center.

In the 3D viewer and exports

The 3D Structure Viewer has its own Show net dipole toggle that draws the same arrow over the 3D model. When you export to SVG with chemistry metadata, the dipole is also written into the file’s embedded data for tools that read it. See SVG metadata.

See also