atomic structure and bonding

Orbital

Region within an atom where an electron is most likely to be found

Ground state

Lowest energy arrangement of electrons into subshells for a given element

Types of d orbitals

xy, xz, yz, x2 - y2, z2

Chromium and copper electron configurations

Unpaired electron in 4s and 5/10 electrons in 3d

Ionic electronic configuration

4s removed before 3d because 4s has more shielding when both subshells are filled

Factors affecting ionisation energy

Distance from nucleus, shielding, nuclear charge, spin-pair repulsion?

Polar bond

Covalent bond in which there is a separation of charge between one end and the other

Types of ionic lattices

Face-centred (co-ordination number 6) and body-centred (co-ordination number 8) when one ion is bigger than the other

Carbon covalent bonding exception

Promotes an electron from 2s to 2p so it can form four covalent bonds. Energy required for this compensated by energetic stability gained from having four covalent bonds

Inert pair

s electrons not used for bonding

Phosphorous exception

Promotes from 3s into 3d so it has five unpaired electrons to form five covalent bonds

Sulphur exception

Promotes one from 3s and one from 3p into 3d to get six unpaired electrons

Dative covalent bonding

When one atom has a lone pair, this can be donated to another to fill its outer shell

Hybridisation trends

Size difference in lobes decreases from sp to sp3

Sigma vs pi bonds

Sigma formed from head on overlap, pi bonds formed from sideways overlap

Double and triple bonds

One sigma and one or more pi bond, pi bond restricts movement so not "freely rotating"

Factors affecting bond strength

Higher for smaller atomic radius, single < double < triple but pi bond generally weaker than sigma bond

Fluorine exception

Short bond length means more repulsion between electrons and between nuclei so weaker bond

Polarity unit

Debyes (D) - amount of charge separation multiplied by distance between centres of charge

Overall dipole?

Dipoles with equal size and opposite directions cancel out (use top to tail vectors)

van der Waals forces

intermolecular forces of attraction

Pd-pd

(Permanent dipole-permanent dipole), Strongest, two molecules which both have dipoles will attract each other with opposite dipoles neighbouring

Id-id

(Instantaneous dipole-induced dipole, London dispersion forces), 2nd strongest, oscillating electron cloud produces a temporary dipole in one molecule which induces a dipole in a neighbouring molecule

Factors affecting strength of id-id

Stronger with more electrons, unbranched molecules have more points of contact so stronger

Hydrogen bonding

Only H-F, O-H, N-H, nucleus of hydrogen atom left exposed when bonding pair attracted to very electronegative element so H then attracts lone pair of electrons from other atom

Properties of water

Due to hydrogen bonding, ice less dense than water, high melting and boiling point, high surface tension

Ideal gas assumptions

Molecules behave as rigid spheres, no intermolecular interactions, collisions perfectly elastic (no loss of KE), individual molecules have no volume, temperature of gas is proportional to average KE of particles

Most likely to behave as ideal gases at...

High temperature, low pressure

Gas equations

pV = nRT, pV = constant, V/T = constant