2.2 and 2.3

2.2 Delocalization and resonance

• If an atom is delocalised, its bonding pairs can switch between 2 different pairs of atoms, where they step outside the boundary given to them.
• This can be noticed between 2 atoms, if a pair appears in one place on one form, then in a different place in a different form.
• A delocalized bond is one that appears in some resonance forms but not others. Resonance form I contains 2 localized bonds and 1 delocalized bond.
• A delocalized charge is a formal charge that appears on one atom in some resonance forms or on other atoms in other forms.

2.3 Hybrid Orbital Theory

• 2 Orbitals combine to create energy levels for specific compounds, and example being Methane.
• They tend to be lower in energy then their un-combined counterparts.
• When hybridization occurs, more stable compounds are able to form.
• Major parts in hybridized orbitals/frontal lobes overlap better than the lobes of unhybridized orbital.
• 

2.3 Hybrid Orbital Theory; sp3 orbitals

• explains tetrahedral shapes of molecules.
• one s sub shell and 3 p sub shells hybridize to form 4 sp3 sub shells.
• there is 25% s character and 75% p character.
• electron repulsion is minimised.
• 

2.3 Hybrid Orbital Theory; sp2 orbitals

• explains the shape of a trigonal planar molecule.
• the 2s orbitals and 2 of the 2p orbitals hybridize to form 3 sp2 orbitals
• 33% s character and 67% p character
• 

2.3 Hybrid Orbital theory; sp orbitals

• 
• explains the structure of linear molecules
• a s orbital and one p orbital hybridize to form 2 sp orbitals.
• 50% s character and 50% p character