Quantum Number and Nuclear Physics (5/13) Flashcards
Atomic forces
Electromagnetic
Gravitational
Strong nuclear
Weak nuclear
Strong nuclear force
Holds protons together in the nucleus (stronger than electromagnetic force)
Bond state
lower energy
more stable
Mass defect
The different of 0.047 x 10^-27 kg of the expected vs actual mass of nucleus
Binding energy
Explains why the mass of the nucleus has a smaller mass combined than the total mass of each individual particle added together
Binding energy equation
E=mc^2
speed of light is squared
measured in eV (electron volts)
m=E/c^2
Wave particle duality
a property of all matter
wavelength= h/ mass*velocity
6.62x10^-34 is h
Heisenberg’s uncertainty principle
says why electrons do not crash into the nucleus due to the attractive force between opposite charges
-electron must be in constant motion
Photoelectric effect
when photons hit surface of metal, they excite metallic electrons to higher energy states causing them to move further
Work function (phi)
E_kinetic=h*f-phi
phi- energy going in
Intensity
corresponds to number of photons
Energy of a photon equation
E_photon=KE_electron + Work function
Isotopes
atoms with the same number of protons, but different number of neutrons
Nuclear reaction
involving nuclear reactions like fusion, fission, nuclear decay, transmutation
Fusion
two or more nuclei forced together with very high energy levels
Releases binding energy
A large amount of energy is used to force two or more nuclei together, leading to the formation of a different element
Fission
Breaks large nucleus into more nuclei (no particles are lost)
Energy can be harvested by nuclear power plant
Radioactive decay
When unstable isotopes break down and eject mass, and energy or photons
Alpha decay
Emission of alpha particle which is two protons and two neutrons (also known as helium nucleus)
-decreases by atomic number of 2 and mass of 4
Beta decay
-: neutron is converted to a proton and an electron is ejected
atomic number goes up by one, but mass does not change
+: proton is converted into a neutron and a positron is ejected
atomic number goes up by one, but mass does not change
atomic number goes down by one, but mass does not change
Electron capture
a nucleus absorbs electron and merges with proton to become an electron
causes atomic number to decrease by one and weight stays same
Gamma decay
excited nucleus, high in energy
no mass or charge so no change in either
just change in energy
Nuclear reaction overall
nuclear particles are never lose entirely
subtract particles bring lost from parent nucleus
Atomic mass and atomic number are unaffected by gamma
Half life
Amount of time for half of the material to decay
Half life equation
N=N0(1/2)^t/t_1/2
Positron emission tomography
short half life injected into body and undergoes beta-plus decay and helps determine where positrons are emitted
