Chapter 9 - Atomic and Nuclear Phenomena Flashcards
Photoelectric effect
Light of a sufficiently high frequency incident on a metal and a vacuum causes metal to emit electrons
Threshold frequency
Minimum frequency of light that causes ejection of electrons
Photons
Light quanta
Work function
Minimum energy required to eject an electron
Absorption of light
Electron jumps from lower to higher energy orbit by absorbing photon
Emission of light
Electron falls from higher to lower energy orbit by emitting photon
Fluorescence
Process in which the electrons of certain substances are excited to higher - energy levels by high frequency photons, and then emit visible light as the energy is released in two or more steps back to ground state
Mass defect
Difference between the sum of the masses of unbound nucleons forming a nucleus and the mass of that nucleus in the bound state
Strong nuclear force
Responsible for the binding of protons and neutrons together in nucleus
Weak nuclear force
Responsible for radioactive decay and contributes to nuclear stability
Binding energy
Allows nucleons to bond
Nuclear reactions
Involve either combining or splitting the nuclei of atoms
Fusion
Small nuclei combined to form larger nucleus
Fission
Large nucleus splits into smaller nuclei
Radioactive decay
Spontaneous decay of certain nuclei accompanied by emission of particles
Alpha decay
Emission of alpha particle
Atomic = -2
Mass= -4
Beta negative decay
Decay of a neutron into a proton Atomic = +1
Mass=no change
Beta positive decay (positron)
Decay of a proton into a neutron
Atomic = -1
Mass = no change
Gamma decay
Emission of gamma rays
- no change to mass or atomic
Electron capture
Absorption of an electron from the inner shell that combines with a proton in the nucleus to form a neutron
Half-life
Time it takes for half of sample to decay
Exponential decay
Rate at which radioactive nuclei decay is proportional to the number of nuclei that remain
