Atomic and nuclear Phenomena

Question 1

photoelectric effect

Answer 1

is the ejection of an electron form the surface of a metal in response to light.

Question 2

Threshold frequency

Answer 2

the minimum light frequency necessary to eject an electron form a given metal. Work function is the minimum energy necessary to eject the electron from a given metal. value depends on metal and can be calculated. Greater the energy of the incident photon above the work function, the more kinetic energy the ejected electron can possess.

Question 3

When electrons are ejected they create a current; the magnitude of this current is proportional to the

Answer 3

intensity of the incident beam of light.

Question 4

Bohr model of the atom

Answer 4

states that electron energy levels are stable and discrete, corresponding to specific orbits .

Question 5

If and electron absorbs photon of light of the same frequency as the difference between orbits, it can

Answer 5

jump from a lower energy to higher energy orbit.

Question 6

When an electron falls form a higher energy orbit

Answer 6

it emits a photon of light of the same frequency as the distance between orbits.

Question 7

apsortioin spectra

Answer 7

may be impacted b small changes in molecular structure

Question 8

fluorescence

Answer 8

occurs when a species absorbs high frequency light and then returns to its ground state in multiple steps. Each step has less energy than the absorbed light and is within the visible range of the EM spectrum.

Question 9

Nuclear4 binding energy

Answer 9

the amount of energy that is released when nucleons (protons and neutrons) bind together. The more binding energy per nucleon released, the more stable the nucleus.

Question 10

What are the 4 fundamental forces of nature

Answer 10

strong and weak nuclear force, which contribute to the stability of the nucleus, electrostatic forces, and gravitation.

Question 11

mass defect

Answer 11

is the difference between the mass of the unbonded nucleons and the mass of the bonded nucleons within the nucleus. The unbounded constituents have more energy and, therefore, more mass than the bonded constituents. The mass defect is the amount of mass converged to energy during nuclear fusion.

Question 12

fusion

Answer 12

occurs when small nuclei combine into larger nuclei

Question 13

fission

Answer 13

occurs when a large nucleus splits into smaller nuclei

Question 14

energy in fusion and fission

Answer 14

is released in both because the nuclei formed in both processes are more stable than the starting nuclei.

Question 15

Radioactive decay

Answer 15

the loss of small particles from the nucleus.

Question 16

alpha decay

Answer 16

emission of alpha particle which is a helium nucleus

A/Z X –> A-4/Z-2 Y + 4/2 a .

Question 17

Beta-negative (B-) decay

Answer 17

the decay of a neutron into a proton, with emission of and electron (e-, B-) and antineutrino (v̅)
A/ZX –> A/Z+1 Y + B-

Question 18

Beta positive (B+) decay or positron emission

Answer 18

the decay of a proton into a neutron, with emmission of a positron (e+, B+) and a neutrino (v)
A/Z X –> . A/Z-1 Y + B+

Question 19

gamma (y) decay

Answer 19

the emission of a gamma ray, which converts a high -energy nucleus into a more stable nucleus
A/ZX* –> A/Z X +y

Question 20

Electron capture

Answer 20

is the absorption of an electron from the inner shell that combines with a proton in the nucleus to form a neutron .
A/Z X + e- –> . A/Z-1 Y

Question 21

Half life

Answer 21

the amount of time required for half of a sample of radioactive nuclei to decay

Question 22

exponential decay

Answer 22

the rate at which radioactive nuclei decay is proportional to the number of nuclei that remain .

Question 23

energy of a photon light

Answer 23

E=hf

Question 24

Max kinetic energy of an electron in the photoelectric effect

Answer 24

Kmax = hf-W

Question 25

Work function

Answer 25

W=Hft .

Question 26

Mass defect and energy

Answer 26

E = MC^2

Question 27

nuclear decay (general form)

Answer 27

A/Z X –> A’/Z’ Y + emitted decay particle

Question 28

Alpha decay

Answer 28

A/Z X –> A-4/Z-2 Y + 4/2 a .

Question 29

Beta negative decay

Answer 29

A/ZX –> A/Z+1 Y + B-

Question 30

rate of nuclear decay

Answer 30

Δn/Δt = -λn

Question 31

Exponential decay

Answer 31

n = n0e^-λt

Question 32

Decay constant

Answer 32

λ = ln2/T(1/2) = 0.693 T/ (1/2)