Molecular orbitals and bonding Flashcards
Skeletal formula points to remember
Functional group should be written in.
If nitrogen is bonded to a hydrogen draw that in.
Sigma bonds
σ end on overlap of atomic orbitals - single bonds
Pi bonds
π side on overlap of atomic orbitals - double bonds (or triple bonds)
Molecular orbitals are ….. stable than atomic orbitals
More
Molecular orbitals have …. energy compared to atomic orbitals
Less
How do two 1s orbitals combine I.e. 2H to H2?
Two 1s spherical orbitals will turn into bead shape.
What is an orbital?
The area which an electron can be found in.
Hybridisation
When orbitals combine to form new identical degenerate hybrid orbitals.
SP^3 hybrid
Mixing of three p orbitals and one s orbitals
SP^2 hybrid
Mixing of two p orbitals and one s orbital
SP hybrid
Mixing of one p orbital and one s orbital
What are stronger sigma bonds or pi bonds?
Sigma bonds as end on overlap is more efficient
Hybrid orbitals are…
Degenerate - equal energy
How can bonding in ethane be described as?
SP^3 hybridisation and sigma bonds.
How can bonding in ethene be described as?
SP^2 hybridisation and one pi bond and the rest sigma bonds.
How can bonding in ethyne be described as?
SP hybridisation and two pi bonds and three sigma bonds
What will determine the type of bonding present in a molecule?
Symmetry and position of bonding orbitals
Pure covalent molecular bonding -
there is no or very little difference in electronegativity between the atoms involved in the bond the bonding orbital will be symmetrical around a point where the bonding electrons are predicted to be found. A fluorine molecule F2 would be an example of where this would be found.
Polar covalent -
For example (Hδ+-Clδ‑) where there is a difference in electronegativity between the two atoms involved in the bond the bonding orbital will be asymmetrical with the bonding electrons more likely to found around chlorine due to it having a larger electronegativity.
Ionic bonds
(Na+Cl‑) where the difference in electronegativity between the two atoms involved in the bond is large, the bonding orbital will be extremely asymmetrical and almost entirely around one of the atoms. In this case it would be around chlorine due to it having a larger electronegativity compared to sodium.
