Quick Steps to Drawing Lewis Structures
Lewis sructures are everywhere in chemistry and being able to draw them quickly and correctly is key to suceeding in any chemistry class. Draw them in seconds with these six easy steps!
Drawing lewis structures is possibly the most useful skill in learning both general and organic chemistry. In this article I will be teaching you how to make quick lewis structures that will in the end be in line-bond structure form.
1. Find the total number of valence shell electrons for all the atoms in the molecule.
- Find the number of valence electrons for each atom using the periodic table. You can determine the number of valence electrons for an element by it group number. ex. Hydrogen has 1 and is in group 1A, carbon has 4 and is in Group 4A and oxygen is in group 6A and has 6 valence electrons.
2. Arrange the atoms
- usually hydrogen atoms will be on the periphery and the more electronegative atoms will be in the center.
3. Add single bonds between each atom
- at first add only a single bond between each atom in the molecule.
4. Assign lone pairs of electrons to peripheral atoms
- Try to fill up the octets of the outer atoms, if you cant start making bonds. Remember that hydrogen at most can have only 1 bond and no lone pairs and that most elements and all non-metals “want” to have a total of eight electrons attached to them and each bond counts as two electrons for both the atoms the bond is attached to.
5. – assign lone pairs to central atoms
- Follow the rules for step 4, except try to fill up the octets for the central atoms. Afterward check that your total mount of electrons is the same as what you started with (remember a bond (a “stick”) counts as a total of 2 electrons.
Rearrange- find best lewis structure or lewis structures by finding the formal charge and drawing out all resonance structures.
Extra – You can now assigning oxidation numbers if you would like to.
If you need more help here is another great lewis structure reference: http://www.bookrags.com/wiki/Lewis_structure
Some examples of finished lewis structures:
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