Atomic Physics

Question 1

what does spectroscopy involve

Answer 1

the measurement of the wavelength frequency and energy of EM radiation

Question 2

deBroglie equation

Answer 2

P=hbar(K) =h/lambd=hv/c

Question 3

Absorption

Answer 3

a photon takes the atom from E_1 to E_2. A photon with energy deltaE = E_2 - E_1 = hv is removed from the radiation field

Question 4

spontaneous emission

Answer 4

AN electron in a higher energy state de-excites to a lower energy state spontaneouslt emitting a phtoton of a specific energy E_if (I= intial energy state, f= final energy state) to the radiation field

Question 5

what type of gas involve emission

Answer 5

hot gas, due to the atoms needing to be in a excited state

Question 6

Bohr first postulate

Answer 6

Electronsmove in circular orbits about the nucleus under the influence of coulomb attraction, obeying classical mechanics.

Question 7

what did Bohr’s first postulate show

Answer 7

the existence of the nucleus

Question 8

Bohr’s second postulate

Answer 8

An electron can only move in an orbit for which its orbital angular momentum L in an integral multiple of hbar L=n(hbar)

Question 9

what did Bohr’s second postulate show

Answer 9

it introduced quantisation

Question 10

Bohr’s third postulate

Answer 10

The electron is stable in its orbit: constant energy E and does not radiate

Question 11

What does Bohr’s third postulate show

Answer 11

It removes problem of stability (by stating that this law of classical mechanics does not apply)

Question 12

Bohr’s Fourth postulate

Answer 12

Absorption and emission are possible through the movement of an electron between two stale orbits, a and b. Radiation frequency v of absorption / emission goes by : V_ab = (E_a - E_b)/h

Question 13

what did Bohr’s fourth postulate show

Answer 13

Basically Einstein’s postulate v=E/h

Question 14

n-fold degenerate

Answer 14

when the total energy of the electron onl depends on n

Question 15

What four things did schordinger’s theory reveal about the properties of the atom

Answer 15

Probability density functions
orbital angular momentum
electron spin
transition rate

Question 16

what are degenerate eigenfunctions

Answer 16

eigenfunctions corresponding to the same eigenvalue are degenerate

Question 17

magnetic dipole in a non uniform field

Answer 17

a magnetic diploe in a non uniform field experiences a torque which will cause precession and a force which will cause displacement.

Question 18

what will atoms experience in a uniform magnetic field

Answer 18

Zeeman effect

Question 19

what will happen to atoms in a non-uniform field (what effect)

Answer 19

atoms undergo displacement due to the stern Gerlach effect

Question 20

what is the Zeeman effect

Answer 20

The Zeeman effect is the splitting of atomic energy levels and the associated spectral lines that result when the atoms are placed in a magnetic field.

Question 21

what did the stern Gerlach experiment show

Answer 21

The experiment showed, qualitatively,that the orientation of atoms in space is quantised.
space quantisation.

it showed that Schrödinger’s theory was not complete due to missing out electron spin.

Question 22

Define total angular Momentum J

Answer 22

J = L + S

where J = total angular momentum
S = torque due to spin
L = orientation

Question 23

Quantum defect

Answer 23

A quantum defect, δ(n,l)—a correction to the principle quantum number, n.

Question 24

anomalous Zeeman effect

Answer 24

The splitting of some spectral lines did not occur as expected in a magnetic field.

Question 25

normal zeeman effect

Answer 25

used to describe lines that split as expected. Ths splitting can be explained by the quantization of angular momentum.

Question 26

3 Things about Normal Zeeman effect

Answer 26

• atomic systems with 0 total spin angular momentum
• applied magnetic field couples to the total orbital angular momentum - the levels split by an amount determined by a constant and the magnetic quantum number m

Question 27

2 things about anomalous Zeeman effect

Answer 27

• occurs for atomic systems that have total sin angular momentum.
• This causes a different splitting ratio in different levels leading to the observation of more than three components to a transition