Writing Electron Dot Structures is a computer program for Mac OS that provides drill with feedback for students learning to write electron dot structures. While designed for students in the first year of college general chemistry it may also be used by high school chemistry students.

A systematic method similar to that found in many general chemistry texts is employed:

1. determine the number of valence shell electrons,
2. select the central atom,
3. construct a skeleton,
4. add electrons to complete octets,
5. examine the structure for resonance forms.

During the construction of a structure, the student has the option of quitting, selecting another formula, or returning to a previous step.

If an incorrect number of electrons is entered the student may not proceed until the correct number is entered. The symbol entered for the central atom must follow accepted upper/lower case practice, and entry of the correct symbol must be accomplished before proceeding to the next step. A periodic table is accessible and feedback provides assistance for these steps.

Construction of the skeleton begins with the placement of the central atom. Atoms can be added, moved, or removed. Prompts and feedback keep the student informed of progress and problems. A correct skeleton is required before proceeding to the next step.

Completion of the structure begins with the addition of electron pairs to form the required bonds. Remaining electrons are added to complete the formation of multiple bonds, assure compliance with the octet rule, and form expanded octets. Resonance forms are made by moving or removing and replacing electron pairs in the existing skeleton. Prompts and feedback guide the student through this process. A running tally of bond pairs, unshared pairs, octets, electrons used, and electrons remaining is provided during this step.

Screens from Writing Electron Dot Structures

Hardware and Software Requirements

Hardware and software requirements for Writing Electron Dot Structures are shown in Table 1.

Ordering and Information

Journal of Chemical Education Software (or JCE Software) is a publication of the Journal of Chemical Education. There is an order form inserted in this issue that provides prices and other ordering information. If this card is not available or if you need additional information, contact: JCE Software, University of Wisconsin­Madison, 1101 University Avenue, Madison, WI 53706-1396; phone; 608/262-5153 or 800/991-5534; fax: 608/265-8094; email: jcesoft@chem.wisc.edu. Information about all of our publications (including abstracts, descriptions, updates) is available from our World Wide Web site at:

http://JChemEd.chem.wisc.edu/JCESoft/