Atomic And Nuclear physics

Question 0

Discovered that electrons could exist in certain specific states of definite energy without radiating away energy, if a certain condition was met by the orbit radius

Answer 0

Bohr

Question 1

Geiger and Marsden’s alpha particles were largely deflected when the nucleus was approached at

Answer 1

Very short distances

Question 2

Energy in electrons is thus… Because they lose energy when making a transition from one state to another of lower energy, and this emitted value equals the difference between states

Answer 2

Discrete

Question 3

Under normal conditions, electrons occupy

Answer 3

Ground state

Question 4

The set of wavelengths of emitted light by the atoms of an element is the

Answer 4

Emission spectrum

Question 5

Electrons take energy and use it in order to make a transition. The wavelengths that are absorbed make the

Answer 5

Absorption spectrum

Question 6

Number of protons in a nucleus is called the

Answer 6

Atomic number

Question 7

Total number of nucleons in atom (protons+neutrons)

Answer 7

Mass number

Question 8

Nuclei that have same atomic number but different mass number

Answer 8

Isotopes

Question 9

Alpha, gamma, and beta radiations…. Air as they pass through it; knock electrons out of atoms

Answer 9

Ionise

Question 10

Positive emissions; identical properties to helium nucleus. Mass number = 4 and atomic number = 2

Answer 10

Alpha

Question 11

Negative emissions, identified as electrons.

Answer 11

Beta

Question 12

Neutral emissions, identified as photons with small wavelengths

Answer 12

Gamma

Question 13

Photons have wavelength of

Answer 13

hc/E

Question 14

The number of nuclei that will decay per second is proportional to the number of atoms present that have not yet decayed.

Answer 14

Law of radioactive decay

Question 15

Mass defect of the nucleus has been converted into …. And is stored in the nucleus

Answer 15

Binding energy

Question 16

Binding energy equivalent to a mass of 1u

Answer 16

931.5 MeV

Question 17

Produces neutrons, which can be used to collide with other nuclei producing a chain, self sustained reaction.

Answer 17

Fission when critical mass is present

Question 18

….Creates… So that electrostatic repulsion between the two nuclei can be overcome

Answer 18

Fusion / plasma

Question 19

Photoelectric effect; …. Of emitted light does not affect the energy of the emitted electrons

Answer 19

Intensity

Question 20

Photoelectric effect; electron energy depends on… Of incident light and there is a certain minimum…. Below which no electrons are emitted

Answer 20

Frequency

Question 21

Electrons are emitted with no time delay

Answer 21

Photoelectric effect

Question 22

Energy of light quanta is given by

Answer 22

E=hf

Question 23

If a photon of frequency f is absorbed by an electron, the electron’s energy will increase by

Answer 23

hf

Question 24

The electron will be emitted only if

Answer 24

Hf>€

Question 25

The difference between hf - €, will be the electron’s

Answer 25

Kinetic energy

Question 26

When electron kinetic energy is zero

Answer 26

Hf=€

Question 27

In photoelectric effect, electron’s kinetic energy equals

Answer 27

eVs

Question 28

In a graph of stopping voltage vs frequency, one obtains a straight line with slope

Answer 28

h/e

Question 29

Photon momentum given by

Answer 29

h / wavelength

Question 30

Assigns wave like properties to particles

Answer 30

De broglie

Question 31

To a particle of momentum p, there corresponds a wave of wavelength

Answer 31

h / p

Question 32

Electron in a box model; electron confined within linear size L, h/p; cannot lose energy, wave is zero at the edges of the box and the wave will be related to L. It will be a

Answer 32

Standing wave

Question 33

If a standing wave has wavelength 2L/n, what is its momentum?

Answer 33

nh/2L

Question 34

What will the kinetic energy of an electron in the box model be?

Answer 34

(n^2*h^2)/(8mL^2)

Question 35

Schrodingers theory assumes an associated wavefunction to… Of position and time

Answer 35

Electron

Question 36

Can be used to find the probability that the electron will be found near x at t

Answer 36

|¥(x , t)|^2

Question 37

When applied to hydrogen, Schrodingers theory predicts that an electron in the atom has quantised energy that depends on energy levels:

Answer 37

-13.6/n^2 , eV

Question 38

Heisenberg states that it is not possible to measure simultaneously the position and momentum of something with indefinite precision

Answer 38

DxDp>=h/4pi

Question 39

Nucleir radii depend on …. ; 1.2xA^(1/3)x10^-15

Answer 39

Mass number

Question 40

Neutron decays into a proton, increasing atomic number by 1, an… And an…

Answer 40

Electron / antineutrino

Question 41

A proton inside a nucleus may decay into a neutron, emitting a… And a…

Answer 41

Positron / neutrino

Question 42

Since the energy of an electron in beta decay has a range of possible values, it means that….. To carry the remainder of available energy

Answer 42

A third light particle must be produced

Question 43

Evidence that nucleus exists in discrete energy levels

Answer 43

Energies emitted from nuclear decay (i.e, alpha, gamma), are discrete

Question 44

In radioactive decay, wavelength symbol represents

Answer 44

Decay constant; represents the probability of decay per unit time