Chapter 9 - Atomic and Nuclear Phenomena

photoelectric effect

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

threshold frequency

minimum frequency of light required to eject an electron

work function

minimum energy required to eject an electron from a metal and depends on the metal

ejected electrons

create a current proportional to the intensity of the incident beam

bohr model

states that electron energy levels are stable and discrete

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 difference between orbits

when an electron falls from a higher energy to

a lower energy it emits a photon of light of the same frequency as the energy difference between orbits

absorption spectra

may be impacted by small changes in molecular structure

fluorescence

occurs when a species absorbs high energy light and then returns to the ground state

nuclear binding energy

amount of energy released when nucleons bind together

the more binding energy per nucleon

the more stable the nucleus

4 fundamental forces of nature

strong and weak nuclear forces, electrostatic forces, gravitation

mass defect

difference between the mass of the unbonded nucleons and mass of the bonded nucleons within the nucleus

unbonded constituents have

more energy and more mass than bonded constituents

the mass defect is the amount

of mass converted to energy during nuclear fusion

fusion occurs

when small nuclei combine into a larger nucleus

fission occurs

when a large nucleus splits into smaller nuclei

energy is released both in fusion and fission because

the nuclei formed in both processes are more stable than the starting nuclei

alpha decay

emission of an alpha particle which is a helium nucleus

beta negative decay

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

beta positive decay

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

gamma decay

emission of a gamma ray which converts a high energy neucleus into a more stable nucleus

electron capture

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