atomic

Question 1

Bohr’s first pstulate

Answer 1

Electrons move in circular orbits about the nucleus under the influence of coulomb attraction, obeying classical mechanics –> exsistence of the nucleus

Question 2

bohrs 2nd postulate

Answer 2

an electron can only move in an orbit for which its orbital angular momentum L is an intergral multiple of hbar (hbar=h/2pi)

L=nhbar n is a integer

–> introduces quantisation

Question 3

bohrs third postulate

Answer 3

the electron is stable in its orbit: constant energyy E and does not radiate
–> removes problem of stability ( by stating that this law of classical mechanics does not apply)

Question 4

bohrs fourth postulate

Answer 4

absoption and emission are possible through the movement of an electron between two stable orbits and a and b. Radiation frequency , v, of absoption/emission given by
v_ab = (Ea-Eb)/h

–>, basically einsteins postualte v=E/h

Question 5

what did sommerfeld do

Answer 5

observed high resolution spectra lines and took inspiration from Bohr’s model to derive an extension on this model

Question 6

what does the sommerfeld extension allow

Answer 6

elliptical orbits as well as circular orbits . All orbits have the same energy. This is keplers law of Ellipses. sommerfeld stated that it is also true for atoms

Question 7

what does k do

Answer 7

distinguish between elliptical and circular orbits.

Question 8

orbital angular momentum quantum numbers

Answer 8

l=0 s sharp
l=1 p principle
l=2 d diffuse
l=3 f fundamental

Question 9

atoms in a uniform magnetic field

Answer 9

will experience Zeeman effect

Question 10

atoms in a non-uniform magnetic field

Answer 10

will undergo displacement–> stern Gerlachh effect

Question 11

the zeeman effect (what did he observe)

Answer 11

that when placed in a magnetic field, an atom’s emission spectrum contains lines that arre split into several components.

Question 12

what is the zeeman effect

Answer 12

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

Question 13

what did the stern-gerlach experiment show

Answer 13

it provided direct proof that the z component of the magnetic dipole moments of atoms is quantised. space qunatisation

Question 14

what did the stern-gerlach experiment involve

Answer 14

the experiment involves directing a beam of silver atoms (produced by a hot oven) through a non-uniform magnetic field. the beam is collimated by an aperture before entering a magnet that produces a magnetic field that increasses in intensity in the z direction

Question 15

what was the result of the stern gerlach experiment

Answer 15

he found that the beam is split into two components, one in the +z direction and the other in the -z direction

Question 16

spin-orbit interaction

Answer 16

an internal magnetic field is associated with the electrons orbital angular momentum.

Question 17

spin orbit coupling

Answer 17

The electron is acted on by a strong internal magnetic field, the orientation of which is determined by L. This produces a torque on its spin magnetic dipole moment, the orientation of which is determined by S. This torque casuses L and S to couple together known as spin orbit coupling

Question 18

define total angular momentum J

Answer 18

J=L+S

Question 19

Pauli Exclusion Principle

Answer 19

A state specified by the quantum number n,l,m can be occupied by at most two electrons, one with spin up and the other with spin down.

Question 20

why do doublets occur

Answer 20

due to the smaller spliiting caused by the psin-orbit interaction . The 3p level is split into j =3/2 and j =1/2 states

Question 21

Normal zeeman effect

Answer 21

Occurs for atomic systems with zero total spin angular momentum

an applied magnetic field couples tothe total orbital angular momentum

the levels split by an amount determined by a constant and hte magnetic quantum number m

Question 22

Anomalous Zeeman effect

Answer 22

occurs for atomic systems that have atotal spin angular momentum

this caues a different splitting ratio in different levels leading to the observation of more that three components to a transition.

Question 23

Emission spectra

Answer 23

: An emission spectrum is composed of a series of discrete spectral lines.
Each line arises from a specific transition between two bound states as an excited
electron de-excites to a lower energy level resulting in the emission of a photon.

Question 24

absoption spectra

Answer 24

An absorption spectrum consists of a continuum with narrow dark lines
appearing at specific wavelengths. These absorption lines arise after a photon is
absorbed, exciting an electron from a lower energy level to a bound upper state

Question 25

production of optical spectra lines

Answer 25

Optical spectral lines occur when an outer (valence) electron makes a
transition between two bound states causing the emission of a photon.

Question 26

production of xray spectral lines

Answer 26

X-ray spectra correspond to states of inner or ‘core’ electrons which are bound in
filled shells

Question 27

Absorption

Answer 27

absorption of a photon takes the atom from a lower energy level E1 to a energetically higher energy level E2. A photon with Delta E= E2-E1=hv is removed from the radiation field

Question 28

spontaneous emission

Answer 28

An electron in a higher energy state, E2 dexcites to a lower energy state E1. spontaneously emitting a photon of specific energy E to the radiation field

Question 29

stimulated emission

Answer 29

emission of photon by atom under the influence of applied radiation field. Two photons result from interaction of a single incoming photon. The ‘new’ photon has the same phase and frequency and travels in the same direction as the incoming photon.

Question 30

what is an absoption edge in an xray spectroscopy

Answer 30

absorption edges are quantum at which the absorption coefficeient jumps to a higher energy value. These edges correspond to the series limits for the K, L , M …, series. The sub shells also appear as edges.