Intramolecular Forces And Potentials

Question 1

Regions of morse potential

Answer 1

Attractive well where potential energy is negative and approaches 0 as the bond length is increased
Repulsive wall where potential energy is positive and rises steeply due to electrostatic repulsion as the bond length decreases, Pauli = electrons can’t occupy same region of space

Question 2

Force

Answer 2

Points in direction of decreasing potential energy, pushes a system towards equilibrium

Question 3

Radial distribution function, g(r)

Answer 3

Probability of finding a particle in a given region of space

Question 4

Radial distribution function of crystals

Answer 4

Series of regular peaks that go to infinite r due to repeating lattice structure, demonstrates long range order

Question 5

Radial distribution function of liquids

Answer 5

Distant particles have random positions and velocities, neighbours close to particle will be in there approximate positions, short range order, peak in g(r) due to first sphere of neighbours and smaller peaks due to secondary neighbours etc

Question 6

Radial distribution function of ideal gas

Answer 6

Completely disordered, equal probability of finding all particles

Question 7

Monopole

Answer 7

Point charge

Question 8

Dipole

Answer 8

Array of charges that overall has no net charge

Question 9

Quadrupole

Answer 9

Array of charges with no overall dipole or charge

Question 10

Dipole-dipole interactions

Answer 10

Attractive, decreases as r^-6

Question 11

Dipole-quadrupole interactions

Answer 11

Attractive, decreases as r^-8

Question 12

Quadrupole-quadrupole interactions

Answer 12

Attractive, decreases as r^-10

Question 13

Induction

Answer 13

Electric field of neighbouring molecules modifies the charge distribution of a molecule

Question 14

Dipole-induced dipole

Answer 14

Electrostatic induction, attractive, decreases as r^-6, independent of temperature

Question 15

Hydrogen bonding

Answer 15

Not entirely electrostatic, partially covalent

Question 16

Periodic boundary conditions

Answer 16

Large number of interacting particles in a box, box surrounded by replicas, particle leaves box but image enters from opposite side therefore N = const