2.2.15 - Sigma and Pi Bonding Flashcards
(14 cards)
What are Sigma bonds?
where orbitals overlap head to head along the bond axis
What do Sigma bonds result in?
single bonds
What kind of orbital do Sigma bonds produce?
a symmetrical molecular orbital
How many electrons can a Sigma bond hold?
2
What are anti-bonding orbitals?
orbitals that explains mathematically where the other electrons have room to go (seeing as each bond can only hold 2 electrons)
What are the descriptors of anti-bonding orbitals?
higher in energy, act to pull nuclei apart, create node/void in electron density between the nuclei, typically empty
What do Pi bonds make up?
the other bonds in double and triple bonds
When do Pi bonds occur?
when p orbitals overlap laterally, above and below the bond axis
What is the resulting bonding molecular orbital of a pi bond?
2 lobes (3D regions) one above and one below of neg charge density
What does the rotation of a pi bond result in?
breaking of the sideways p orbital overlap which results in a chemical reaction
why can Sigma bonds rotate?
because the bond axis remains unchanged/ the bond is symmetrical around the bond axis
How are triple bonds formed?
2 pi bonds in addition to the Sigma bond
in a triple bond, where does the second pi bond form?
from the sideways overlap of the pz orbital, perpendicular to the bond axis forming lobes in front and behind the bond axis
How do the bonds order from weakest and longest to strongest and shortest?
single bonds (Sigma), double bonds (Sigma + Pi), triple bonds (Sigma + Pi + Pi)
