Molecular Bonding Flashcards
Describe aspects of Lewis Theory
- IONIC
- COVALENT
BONDING uses VALENCE e-s
VSPER
FORMAL CHARGES
Ionic: valence e- transfer from metal to non-metal to achieve OCTET.
Covalent: valence e- pairs shared between atoms to achieve OCTET.
BONDING & LONE PAIRS.
Define electronegativity
tendency of an atom to attract a bonding pair of electrons
What is formal charge?
Formal charge = valence e-s - (lone pair e-s + 1/2 bonding e-s)
What is a polar covalent bond?
Unequal sharing of e-s due to difference in EN.
What is an ATOMIC ORBITAL?
Area around a nucleus where e-s are likely found.
State the shape of an s AO.
SPHERICAL
State the shape of a p orbital
DUMBELL
What is a NODE?
Region of ZERO probability of finding an e-
Where waves of opposite phases DESTRUCTIVELY overlap & cancel.
Compare the energy of a p & s orbital
p orbital HIGHER ENERGY than s
Describe the shape of a p orbital
DUMBELL split by a NODAL PLANE into 2 lobes.
3 DEGENERATE p AOs w symmetry about x, y, z axes.
Why do AOs combine to form MOs?
To achieve a MORE STABLE, LOWER ENERGY state.
Describe the MO theory
AOs combine to MOs.
Aufbau principle states…
e-s fill lowest energy orbitals first.
Pauli exclusion principle states
max. 2 e-s occupy an orbital, of opposite spins
Hund’s rule states
for degenerate AOs, e-s occupy empty orbitals first
antibonding orbitals:
e-s NOT located between 2 distinct nuclei
HIGHER ENERGY
bonding orbitals:
HIGH e- DENSITY between nuclei.
LOWER ENERGY
Compare energy states of bonding & anti-bonding orbitals
AB > B
END ON OVERLAP forms __ bonds
σ bonds
SIDE-TO-SIDE OVERLAP forms __ bonds
∏ bonds
Compare strength of σ & ∏ bonds
σ > ∏
HOMO =
Highest Occupied Molecular Orbital - filled MO highest in energy
LUMO =
Lowest Unoccupied Molecular Orbital - empty orbital above HOMO.
DESTRUCTIVE CANCELLATION ->
No e- density between 2 nuclei
ANTIBONDING
