Topic 1-Molecular Orbitals and Stereochemistry Flashcards
Sigma bond is created when
P or S orbitals end-on overlap along the axis of the covalent bond are called sigma
Pi bonds are created when
P orbitals overlap side-on of parallel atomic orbitals that lie perpendicular of the axis of the covalent bond
When electrons absorb electromagnetic radiation-
They move to a higher energy molecular orbitals
LUMO
Lowest unoccupied molecular orbital
HOMO
Highest Occupied Molecular Orbital
Coloured organic compounds contain delocalised electrons within bonding molecular orbitals which extend across many atoms, this is known as
A conjugated system
The greater the number of atoms in the conjugated system
The lower the energy gap between the HOMO and the LUMO
Chromophore is the group of atoms within a molecule responsible for absorbing visible light
If it absorbs light of one colour the compound will exhibit the complementary colour
When the group is on the same side of the double bond
It is a cis-bond, these bonds are weaker than trans bonds
When the group is on the opposite side of the double bond
Trans-bond, these bonds are stronger so they have a higher melting point
Optical isomers
Molecules that are non-super-imposable, mirror images of each other. These are known as enantiomers.
Enantiomers rotate polarised light
In an equal and opposite way.
Enantiomers are said to be
Optically active
Enantiomers that have equal proportions is called
A racemic mixture, these are not optically active.
How do sp2 orbitals form
S orbitals merging with 2p orbitals to forming 3sp2 orbitals
