Drawing the Lewis Structure for C3H8 (Propane)

Viewing Notes:

• With C3H8 there are only single bonds. Whenever you see a compound made of Carbon and Hydrogen that ends in -ane that means it will only have single bonds.
• Remember that Hydrogen (H) atoms always go on the outside of a Lewis Structure.
• Note that Hydrogen only needs two valence electrons to have a full outer shell.
• In the Lewis structure for C3H8 there are a total of 20 valence electrons.

Transcript: This is the C3H8 Lewis structure: Propane. We have 4 valence electrons for Carbon--we have 3 Carbons. We have 1 valence electron for Hydrogen--8 Hydrogens. Add them up, we get a total of 20 valence electrons for the C3H8 Lewis structure. We'll put the 3 Carbons in a row and the Hydrogens will go around them. The Carbons on the end will have 3 Hydrogens. The Carbons in the center will have 2. So each Carbon is bonded to four different things.

Next we'll put a line between atoms to have a chemical bond--that represents 2 valence electrons--until we use all the valence electrons up. So we've used all 20 valence electrons for the C3H8 Lewis structure.

Each Hydrogen has a single bond--that's two valence electrons--so its outer shell is full. And for the Carbons, each Carbon has four single bonds, so that's 8 valence electrons, and that's an octet for the Carbon. So we've satisfied the octets on each of the Carbon atoms.

So that's the Lewis structure for C3H8: Propane. This is Dr. B., and thanks for watching.

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