L1 Flashcards
how does delocalisation increase stability of a molecule?
delocalisation of electrons across PARALLEL ALIGNED P-ORBITALS.
what is valency?
the maximum number of univalent atoms for which an atom of that element can be substituted.
what is aromaticity?
RING of unsaturated bonds, lone pairs or empty orbitals exhibit stronger stabilisation than expected by that of conjugation alone.
what does the increased stability of aromatic compounds make them useful for?
scaffolds onto which fgs can be grafted.
what happens to a photon absorbed by a chromophore?
it is emitted at a longer wavelength.
what happens in a conjugated system (e.g. retinal cofactor) when an electron absorbs a photon?
ELECTRON becomes excited –> PI bond rotates –> isomerisation (cis to trans) –> conformational change –> electrical impulse.
what is the partition coefficient?
distribution of a compound between water and ocatanol (approximation of distribution between cytosol and lipid membrane).
what is a conjugated system?
alternating single and double bonds leading to general delocalisation across all adjacent parallel aligned p orbitals.
describe Aufbay, Hund and Pauli Exclusion.
A - electrons enter subsequently increasing energy orbitals
PE - no more than 2 electrons per orbital
Hund - degenerate orbitals fill first.
what two things determine bind length?
atomic radius and nature (double or single).
