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Writing Electron Dot Structures is a computer program for Mac OS and
Windows 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.
- Determine the number of valence shell electrons.
- Select the central
atom.
- Construct a skeleton.
- Add electrons to complete octets.
- Examine the structure for resonance
forms.
During the construction of
a structure, students have the option of quitting, selecting another formula,
or returning to a previous step. If the “select
another formula” option is chosen, the user will be informed of the
status of available formulae for the session (structures attempted but not
completed, structures completed and structures not attempted).
If an incorrect
number of electrons is entered, students may not proceed until the correct
number is entered. The symbol entered for the central atom
must follow accepted upper- and lowercase 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 students
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 students through
this process. A running tally of bond pairs, unshared pairs, octets, electrons
used, and electrons remaining is provided during this step.
A screen from Writing Electron Dot Structures.
Writing Electron
Dot Structures requires the following software, which is available for
free download from the Internet: Netscape Navigator,
version 4.75 or higher, or Microsoft Internet Explorer, version 5.0 or
higher,
and
Shockwave Player (available from Macromedia).
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