Atomic And Nuclear physics Flashcards

0
Q

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

A

Bohr

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1
Q

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

A

Very short distances

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2
Q

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

A

Discrete

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3
Q

Under normal conditions, electrons occupy

A

Ground state

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4
Q

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

A

Emission spectrum

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5
Q

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

A

Absorption spectrum

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6
Q

Number of protons in a nucleus is called the

A

Atomic number

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7
Q

Total number of nucleons in atom (protons+neutrons)

A

Mass number

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8
Q

Nuclei that have same atomic number but different mass number

A

Isotopes

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9
Q

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

A

Ionise

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10
Q

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

A

Alpha

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11
Q

Negative emissions, identified as electrons.

A

Beta

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12
Q

Neutral emissions, identified as photons with small wavelengths

A

Gamma

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13
Q

Photons have wavelength of

A

hc/E

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14
Q

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

A

Law of radioactive decay

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15
Q

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

A

Binding energy

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16
Q

Binding energy equivalent to a mass of 1u

A

931.5 MeV

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17
Q

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

A

Fission when critical mass is present

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18
Q

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

A

Fusion / plasma

19
Q

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

20
Q

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

21
Q

Electrons are emitted with no time delay

A

Photoelectric effect

22
Q

Energy of light quanta is given by

23
Q

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

24
The electron will be emitted only if
Hf>€
25
The difference between hf - €, will be the electron's
Kinetic energy
26
When electron kinetic energy is zero
Hf=€
27
In photoelectric effect, electron's kinetic energy equals
eVs
28
In a graph of stopping voltage vs frequency, one obtains a straight line with slope
h/e
29
Photon momentum given by
h / wavelength
30
Assigns wave like properties to particles
De broglie
31
To a particle of momentum p, there corresponds a wave of wavelength
h / p
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
Standing wave
33
If a standing wave has wavelength 2L/n, what is its momentum?
nh/2L
34
What will the kinetic energy of an electron in the box model be?
(n^2*h^2)/(8mL^2)
35
Schrodingers theory assumes an associated wavefunction to... Of position and time
Electron
36
Can be used to find the probability that the electron will be found near x at t
|¥(x , t)|^2
37
When applied to hydrogen, Schrodingers theory predicts that an electron in the atom has quantised energy that depends on energy levels:
-13.6/n^2 , eV
38
Heisenberg states that it is not possible to measure simultaneously the position and momentum of something with indefinite precision
DxDp>=h/4pi
39
Nucleir radii depend on .... ; 1.2xA^(1/3)x10^-15
Mass number
40
Neutron decays into a proton, increasing atomic number by 1, an... And an...
Electron / antineutrino
41
A proton inside a nucleus may decay into a neutron, emitting a... And a...
Positron / neutrino
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
A third light particle must be produced
43
Evidence that nucleus exists in discrete energy levels
Energies emitted from nuclear decay (i.e, alpha, gamma), are discrete
44
In radioactive decay, wavelength symbol represents
Decay constant; represents the probability of decay per unit time