➖Sigma bond vs Pi bond〰️
Covalent bonds come in two types. Sigma and pi bonds differ in how their orbitals overlap and how strong they are.
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➖Sigma bond
- ✓Formed by head-on orbital overlap
- ✓Strong, with electron density on the bond axis
- ✓Always the first bond between two atoms
- ✓Allows free rotation around the bond
- ✓Present in all single bonds
〰️Pi bond
- ✓Formed by sideways orbital overlap
- ✓Weaker, with density above and below the axis
- ✓Only forms after a sigma bond exists
- ✓Prevents rotation around the bond
- ✓Present in double and triple bonds
Verdict
A sigma bond is the strong first bond from head-on overlap; pi bonds are weaker sideways overlaps added in double and triple bonds. Pi bonds lock the molecule against rotation.
Frequently asked
Which bond is stronger?+
The sigma bond, because head-on overlap concentrates electron density most effectively.
How many bonds are in a triple bond?+
A triple bond has one sigma bond and two pi bonds.
Why can't double bonds rotate?+
The pi bond's sideways overlap would break if the atoms rotated, so rotation is blocked.
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