Nuclei and Particles Flashcards
Atomic Mass (A), Atomic no (Z)
A=protons+Neutrons, Z=Protons
Isotope
Same element, different atomic mass. different no of neutrons
isotope notation
2 numbers in front of element symbol (upper for atomic mass, lower for atomic no)
Nucleon
collective name for protons and neutrons
Ion
one or more electrons added or removed from neutral atom….electrically charged ion formed
speed of light
3 x 10^8 ms-1
energy and mass interchangeable due to e=mc^2
so can refer to subatomic particles by their energy not mass (mass energy). MeV mega electronvolts). Or expressed as E/c^2 in keV (kilo electron volts (thousand electron volts)
Proton mass
proton almost 2000 times more massive than electron
Antimatter
Same mass as matter counterparts, but attributes have opposite sign (eg electron charge)
positron
Antimatter counterpart of electron
antiproton
Antimatter counterpart of proton
Matter - antimatter annihilation
Collision between matter and antimatter. particle + antiparticle…photons. Large amount of energy
Pair production
photons…Particle + antiparticle
Energy time uncertainty principle.
Time a particle can exist with “borrowed” energy. Rearranged to delta t = h/(4pi x delta E) to find time…orig eq: delta E x delta t is approx = to h/4pi
Quantum jump
Occur between energy levels. For nuclei, gamma ray photons emitted, hundreds of thousands of times more energy than with visible photons. 1MeV(mega electron volt) compared to 2 or 3 eV
Mass defect, binding energy
Amount by which the nucleus is less massive than its constituent parts. Binding energy also this amount, so also the same amount of energy need to break apart the nucleus
Alpha decay and particle
Emitted during decay,same as helium nucleus, 2 protons 2 neutrons
Binding energy of alpha particle
28.3 meV
Beta decay
Transformations between neutrons and protons at the heart of it. Beta - decay, beta + decay, electron capture all types of beta decay
conservation in nuclear processes
mass, energy, net charge conserved
Beta minus decay
Neutron to proton, electron and electron antineutrino (zero charge) created. Extra proton, 1 less neutron so atomic mass same, atomic no +1.
Beta plus decay
Proton to neutron, so atomic no -1. Positron (+ as antielectron) and electron neutrino (zero charge) created
Electron capture
Nucleus captures an electron, proton interacts with electron forming a neutron, emitting electron neutrino. Atomic no decreases by 1
Gamma decay
Nucleus in excited state (from decay), quantum jump to lower energy state, photon emission. Similar process to atoms but gamma ray photon about a million times larger