MOLECULAR ORBITALS Flashcards
How do molecular orbitals form
when atomic orbitals combine
how are sigma bonds formed
end-on overlap of atomic orbitals along the axis of the
covalent bond
how are pi bonds formed
side-on overlap of parallel atomic orbitals that lie
perpendicular to the axis of the covalent bond
What is hybridisation
The process of mixing atomic orbitals within an atom to generate a set of new atomic orbitals called hybrid orbitals
-The orbitals are degenerate
What type of hybridisation do alkanes have
sp3
2s orbital and the three 2p orbitals of carbon hybridise
What type of hybridisation do alkenes have
(benzene also has this)
sp2
The 2s orbital and
two of the 2p orbitals hybridise to form three degenerate sp2 hybrid orbitals
What type of hybridisation do alkynes have
sp
The 2s orbital and
one 2p orbital of carbon hybridise to form two degenerate hybrid orbitals
why do most organic molecules appear colourless
e the energy difference between HOMO and LUMO is relatively large.
-This results in absorption of light from the ultraviolet region of the spectrum
what is a chromophore
single double bond responsible for light absorption
What do large conjugated systems suggest
small energy gap between HOMO and LUMO
What happens when a compound absorbs a colour what colour is observed
the complimentary colour
