Electron Flow Arrows

Electron flow arrows show the actual direction of motion of the electrons. They can point from an electron or lone pair of an atom or a bond to another atom, bond, or even to an incipient bond (formed after the electron transition).

Draw an Electron Flow Arrow

  1. Select the arrow type (single electron flow or electron pair flow). The arrows are available through Insert > Electron Flow.

  2. Click a bond, electron, or lone pair (or over the atom itself if the valence electrons are not displayed around it) of the structure on the canvas.

  3. Select the destination by dragging the arrow.

  4. Click the desired destination to finalize the electron flow arrow.

    images/download/attachments/1802563/electronflow.png

When the arrow is drawn from an electron or lone pair, or an atom the target can be one of the following:

  • An atom

  • A bond

  • An incipient bond between this atom and any other atom

When the arrow is drawn from a bond, the target can be one of the following:

  • An atom

  • A bond

  • An incipient bond between this atom and any other atom

If one endpoint of the electron flow arrow is in an S-group and the other is not, the arrow must connect to the attachment point of S-group.

A single electron flow arrow can be drawn from the following starting points:

  • A radical

  • An electron of a lone pair

  • An atom label if neither radicals nor lone pairs are displayed on the atom

If the atom has more than one radicals and/or lone pairs, the starting radical or lone pair can be freely selected.

An electron pair flow arrow can be drawn the following starting points:

  • A lone pair

  • A charge if lone pairs are not displayed

  • An atom label if the atom does not have any charge and lone pairs are not displayed

If the atom has more than one lone pairs, the starting lone pair can be freely selected.

If several electron flow arrows start from the same atom, MarvinSketch ensures that their arrangement is chemically correct. The following rules are used:

  • No more than one single electron flow arrow can start from a radical.

  • No more than two single electron flow arrows can start from a lone pair.

  • No more than one electron pair flow arrow can start from a lone pair.

If the source of an electron flow arrow is a bond, the electron flow arrow is drawn from the midpoint of the bond.

An electron flow arrow can be drawn to the following:

  • An atom label

  • The midpoint of a bond

  • The midpoint (single electron flow) or the 3/4 point (electron pair flow) of the distance between two atoms in case of incipient bonds