Unit 7: Atomic and Nuclear Physics

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The smallest particle into which anything can be broken
The negative sub-particle discovered through Thomson’s cathode ray tube experiment.
The region consisting of the neutrons and protons revealed through Rutherford’s gold foil experiment where some electrons were scattered by the gold foil: Geiger-Marsden Experiment.
The existence of the positively charged sub-particle, proton, was revealed by the fast-moving alpha particle interacting with a nitrogen nucleus where the nucleus was transmuted into oxygen and emission of hydrogen nucleus.
The neutral particle inside the nucleus was proposed by Chadwick by testing penetrating radiation with alpha particles.
Emission Spectrum
Formed when different elements become hot enough and give off light; The light an element emits that is not continuous, but contains only a few characteristic colors, which contains specific frequencies that correspond to specific colors.
Absorption Spectrum
The spectrum produced by light from other sources (e.g. the sun) showing most frequencies with a few missing; continuous spectrum of light when light is shone through an element in gaseous form.
The “packets” of energy emitted as light, with the energy E, given by E = hf.
Electronvolt (eV)
A derived unit defined as the charge on one electron when moved through a p.d. of one volt. Relative to 1.6 x 10^-19 J.
Strong Nuclear Force (interaction)
Force keeping protons and neutrons together with a short range that only acts within the nucleus between nucleons.
Weak Interaction
The fourth force explaining the aspects of the nucleus such as beta decay that can take place inside a particular nucleus; responsible for the disintegration of a neutron into a proton and an electron in beta decay.
Daughter Nuclide
The product of a radioactive decay (alpha or beta) that is created to comply with the conservation laws for mass and charge.
Binding Energy
The energy released to assemble a nucleon from its protons and neutrons together in the nucleus, defined by the equation E = mc². m = mass defect, c = speed of light in a vacuum.
Mass Defect
The difference between the masses of the nucleus and its component nucleons; A measure of the binding energy.
Geiger Counter
An instrument used to detect and count the number of ionizations taking place inside the GM tube.
Artificial Transmutation
The transformation of atoms of one element into atoms of another element as a result of a nuclear reaction, such as bombardment with neutrons.
An atom with a particular nucleus configuration referred to by chemical symbol followed by its mass number for that particular nuclide.
Radioactive Decay
The spontaneous process involving the emission of an alpha particle or beta particle, or gamma rays, where the parent nucleus undergoes a change of atomic number to where it becomes the nucleus of a different element.
Radioactive Half-life
The time taken for the number of radioactive nuclei present to halve in value.
Nuclear Fission
The nuclear reaction whereby large nuclei are induced to break up into smaller nuclei and release energy in the process.
Chain Reaction
Occurs when three produced neutrons from bombarding a uranium nucleus with a neutron.
Nuclear Fusion
The nuclear reaction whereby small nuclei are induced to join together into larger nuclei and release energy in the process; fuels all stars, but is not yet achievable due to high pressures needed to reach the plasma state.
Categories: Atomic Physics