Organic Chemistry

Learn the toughest concepts covered in Organic Chemistry with step-by-step video tutorials and practice problems by world-class tutors.

1. A Review of General Chemistry

Octet Rule

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This might be the most important rule in all of undergraduate chemistry! Let’s start from the beginning and go from there.  

Noble Gas Configuration

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concept

How Noble gases are related to the octet rule.

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The tendency for atoms to share electrons to reach their Noble gas configuration is known as the Octet Rule

LCAO of Noble Gases

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concept

LCAO model proves why Noble gases are so stable.

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The LCAO of He2

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Science-y Version: Helium would have to fill an anti-bonding molecular orbital in order to bond to itself, which undoes the extra stability provided by the filled bonding orbital, so it has no reason to make a bond.

Basic Version: Noble gases don’t like to bond to anything!  

Periodic Table Patterns


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concept

The most important parts of the periodic table for organic chemistry

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Content
  • Only worry about the elements on the first 2 or 3 rows. Living systems don’t have a lot of heavy metals!
  • Periods = Rows, Groups = Columns.
  • Remember your Group 1A through 8A elements. We will practice memorizing the top atom of each group. 

Octet Rule Details

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concept

The octet rule.

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  • First-row elements (H, He, Li) will prefer to possess 2 octet electrons
  • Second-row elements (C, N, O, F) will prefer to possess 8 octet electrons
  • Atoms smaller than carbon will possess less than 8 electrons:(Be) = 4 and (B) = 6
  • Third-row elements may form expanded octets that can hold up to (P) = 10 and (S) = 12 electrons.

Octet electrons is the name we give to ALL electrons that surround an atom. These help the atom reach its Noble gas configuration.

  • Bonds = 2 Octet Electrons
  • Lone Pairs = 2 Octet Electrons

It seems like a lot to memorize, so let’s just knock out some practice problems. 

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Problem

PRACTICE:Analyze the following molecules. Indicate ALL atoms that are in violation of the octet rule.

From now on let’s just agree that hydrogens with 1 bond and carbons with 4 bonds follow the octet rule, instead of multiplying them out every time. 

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Problem

PRACTICE:Analyze the following molecules. Indicate ALL atoms that are in violation of the octet rule.

You’ll keep seeing the octet rule a bunch more in this chapter. Let’s move on.