Physics and Math Chapter 9: Atomic and Nuclear Phenomena

Question 1

Photoelectric effect

Answer 1

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

Question 2

Threshold frequency

Answer 2

is the minimum light frequency necessary to eject an electron from a given metal.

Question 3

Work function

Answer 3

the minimum energy necessary to eject an electron from a given metal. Its value depends on the metal used and can be calculated by multiplying the threshold frequency by Planck’s constant

Question 4

Greater the energy of the incident photon above the work function —

Answer 4

the more kinetic energy the ejected electron can possess.

Question 5

Magnitude of ejected electrons current is

Answer 5

proportional to the intensity of the incident beam of light.

Question 6

Bohr model of the atom

Answer 6

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

Question 7

When an electron absorbs a photon of light of the same frequency as the energy difference between the orbits

Answer 7

it can jump from a lower-energy to a higher energy orbit

Question 8

When an electron emits a photon of light of the same frequency as the energy difference between the orbits

Answer 8

it falls from a higher-energy to a lower energy orbit

Question 9

Absorption spectra can be impacted by:

Answer 9

small changes in molecular structure.

Question 10

Flourescence

Answer 10

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 electromagnetic spectrum.

Question 11

Nuclear binding energy

Answer 11

the amount of energy that is released when nucleons (protons and neutrons) bind together.

Question 12

The more binding energy per nucleon released…

Answer 12

the more stable the nucleus

Question 13

The four fundamental forces of nature are the:

Answer 13

strong and weak nuclear force (contributes to stability)
Electrostatic forces
Gravitation

Question 14

Mass defect

Answer 14

the difference between the mass of the unbound nucleons and the mass of the bound nucleons within the nucleus.
Also - the amount of mass converted to energy during nuclear fusion.

Question 15

Which nucleons have more energy and mass?

Answer 15

unbound constituents

Question 16

Fusion

Answer 16

occurs when small nuclei combine into larger nuclei

Question 17

Fission

Answer 17

occurs when a large nucleus splits into smaller nuclei.

Question 18

In both fusion and fission, energy is

Answer 18

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

Question 19

Radioactive decay

Answer 19

the loss of small particles from the nucleus

Question 20

Alpha decay

Answer 20

the emission of an alpha particle which is a helium nucleus

Question 21

Beta-negative decay

Answer 21

the decay of a neutron into a proton, with emission of an electron and an antineutrino

Question 22

Beta-positive decay (positron emission)

Answer 22

decay of a proton into a neutron, with emission of a positron and a neutrino

Question 23

Gamma decay

Answer 23

the emission of a gamma ray, which converts a high-energy nucleus into a more stable nucleus.

Question 24

Electron capture

Answer 24

the absorption of an electron from the inner shell that combines with a proton in the nucleus to form a neutron.

Question 25

Half-life

Answer 25

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

Question 26

Exponential decay

Answer 26

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