Ch. 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

Minimum light frequency necessary to eject an electron from a given metal

Question 3

Work Function

Answer 3

Minimum energy necessary to eject an electron from a given metal. Value depends on the metal used and can be calculated by multiplying the threshold frequency by Planck’s constant. The greater the energy of the incident photon above the work function, the more kinetic energy the ejected electron can possess

Question 4

Ejected electron current

Answer 4

The ejected electrons create a current; the magnitude of this current is proportional to the intensity of the incident beam of light

Question 5

Bohr model of the atom

Answer 5

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

Question 6

Absorbing

Answer 6

An electron can jump from a lower energy to a higher energy orbit by absorbing a photon of light of the same frequency as the energy diff between the orbits. When an electron falls from a higher energy to a lower energy orbit it emits a photon of light of the same frequency as the energy diff between the orbits

Question 7

Absorption Spectra

Answer 7

May be impacted by 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 electromagnetic spectrum

Question 9

Nuclear Binding Energy

Answer 9

Amt 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

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

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

Question 12

Fusion

Answer 12

Occurs when small nuclei combine into larger nuclei. Energy is released in both fusion and fission bc the nuclei formed in both processes are more stable than the starting nuclei

Question 13

Fission

Answer 13

Occurs when large nucleus splits into smaller nuclei. Energy is released in both fusion and fission bc the nuclei formed in both processes are more stable than the starting nuclei

Question 14

Radioactive decay

Answer 14

The loss of small particles from the nucleus

Question 15

Alpha decay

Answer 15

Emission of an alpha particle, which is a helium nucleus

Question 16

Beta negative decay

Answer 16

Decay of a neutron into a proton with emission of an electron and an antineutrino

Question 17

Beta positive decay

Answer 17

Also called positron emission is the decay of a proton into a neutron, with emission of a positron and a neutrino

Question 18

Gamma decay

Answer 18

Emission of a gamma ray, which converts a high energy nucleus into a more stable nucleus

Question 19

Electron capture

Answer 19

Absorption of an electron from the inner shell that combines w a proton in the nucleus to form a neutron

Question 20

Half life

Answer 20

Amt of time required for half of a sample of radioactive nuclei to decay

Question 21

Exponential decay

Answer 21

Rate @ which radioactive nuclei decay is proportional to the number of nuclei that remain