Writing Lewis Structure

 

1. Determine total number of electron dots to be used by adding up the valance electrons on each atom, Divide the number by 2 to determine how many electron pairs.

2. Write chemical symbols of the atoms to show how they are bonded. The atom which can hold the greater number of e- goes (think symmetry.) in the center.

3. Use electron pairs to form single bonds linking atoms.

4. Try placing any remaining electron pairs around atoms to complete their octets (or duplet for H). Multiple bonds may be used.

- Terminal halogen atoms always have three lone pairs and for only single bonds.

- Terminal oxygen and sulfur atoms form either one or two bonds and have either three or two (one pairs)

-Terminal nitrogen atoms may have up to three bonds.

VSPER

Valance - shell electron-pair repulsion theory

- positions taken up by electron pairs in the valance shell assuming all pairs move as far apart from one another as possible.

These are general guidelines - they won’t work all the time!!