lewis structures with 4 "dots"

Some of our instructors have asked that we change the way we draw Lewis structures. In introductory chemistry classes it is common to "build up" a Lewis structure by adding electrons one-at-a-time. "Dots" are not paired until there are at least 4 of them on the canvas, thus indicating the number of bonds that could potentially be made from each atom. (H gets 1 single dot; Be gets 2 single dots; B gets 3 single dots; C gets 4 single dots; N gets 3 single dots; O gets 2 single dots; F gets 1 single dot) Working towards the octet rule, this means that C should have 4 "dots" and N should have 5 "dots" (3 singles and 1 pair). At this point in the curriculum students have not heard of the concepts of "lone pairs" and "radicals" (much less electron spin states). The standard tools in MarvinSketch only allow for "lone pairs" and various "radical" electrons to be put on the canvas.

Instructors have asked that we represent Lewis structures as shown in the first image (#451: N with 3 single dots and 1 paired set of dots) instead of the second image (#024: N with 2 lone pairs and 1 radical electron).

Is there any way to achieve this?

I tried to put 4 dots on C, but found I couldn't do it with the standard button set.

Also, using the radical button to achieve the desired configuration around N involves using terminology that is not known to undergraduate students.

What are your recommendations on using MarvinSketch for this purpose and how to achieve it?

 

Thanks.

 

Hi Michiel,

In MarvinSketch the highest radical state you can assign to an atom is Trivalent Quartet. With this one you can already set the electrons as on the second image you attached (143451.jpg: three single and one pair of dots). Unfortunately, there is presently no way to display four single dots on an atom.

Furthermore, if you refer to the student examination example (http://www.chemaxon.com/marvin/examples/applets/sketch/studentexam/index.html), where a specific button is created for setting the radical electron explicitly: with this one you can set only the Monovalent radical status on or off (it was implemented upon a custom development for a client, and this client didn't want more radical states to be able to set.

So I'm sorry, but presently it is not possible, and IMHO, unless it is developed as e.g. a custom development, this feature will not be available in MarvinSketch.

Best regards,

Akos