Chapter 21 Vocabulary: Nuclear Chemistry

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What to Know For the Final From This Chapter
– Types of Radioactive Decay
– Difference between fusion and fission
name for collectively calling protons and neutrons
an atom. identified by the number of protons and neutrons in its nucleus. Can be represented in two ways
88 Ra (superscript=mass number, subscript is atomic number) is the same as radium-228.
Mass Defect
the difference between the mass of an atom and the sum of the masses of its protons, neutrons, and electrons.
Nuclear Binding Energy
the energy released when a nucleus is formed from neutrons, or the amount of energy required to break apart the nucleus.
Nuclear Shell Model
a theory that nucleons exist in different energy levels, or shells, in the nucleus.
Magic Numbers
the numbers of nucleons that represent completed nuclear shells (2, 8, 20, 28, 50, 82, 126).
Nuclear Reaction
a reaction that affects the nucleus of an atom.
a change in the identity of a nucleus as a result of a change in the number of its protons.
Radioactive Decay
the spontaneous disintegration of a nucleus into a slightly lighter nucleus, accompanied by emission of particles, electromagnetic radiation, or both.
Nuclear Radiation
particles or electromagnetic radiation emitted from the nucleus during radioactive decay.
Radioactive Nuclide
an unstable nucleus that undergoes radioactive decay.
Alpha Particle (α)
two protons and two neutrons bound together and is emitted from the nucleus during some kinds of radioactive decay (the atomic number decreases by two, the mass number decreases by four). Helium nuclei. Have a charge of 2+.
Beta Particle (β)
an electron emitted from the nucleus during some kinds of radioactive decay (the atomic number increases by one, the mass number does not change).
Positron Emission
emits a positron to decrease the number of protons. The atomic number decreases by one but the mass number does not change.
a particle that has the same mass as an electron, but has a positive charge, and is emitted from the nucleus during some kinds of radioactive decay.
Electron Capture
an inner orbital electron is captured by the nucleus of its own atom (the atomic number decreases by one but the mass number does not change).
Gamma Rays
high-energy electromagnetic waves emitted from a nucleus as it changes from an excited state to a ground energy state.
the time required for half the atoms of a radioactive nuclide to decay.
Decay Series
a series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is reached.
Parent Nuclide
the heaviest nuclide of each decay series.
Daughter Nuclides
the nuclides produces by the decay of the parent nuclides.
Artificial Transmutations
bombardment of nuclei with charged and uncharged particles.
Transuranium Elements
elements with more than 92 protons in their nuclei.
Roentgen (R)
a unit used to measure nuclear radiation exposure. It is equal to the amount of gamma and X-ray radiation that produces 2×10⁹ ion pairs when it passes through 1 cm³ of dry air.
Roentgen Equivalent, Man (rem)
a unit used to measure the dose of any time of ionizing radiation that factors in the effect that the radiation has on human tissue.
Film Badges
use exposure of film to measure the approximate radiation exposure of people working with radiation.
Geiger-Müller Counters
instruments that detect radiation by counting electrical pulses carried by gas ionized by radiation.
Scintillation Counters
instruments that convert scintillating light to an electric signal for detecting radiation.
Radioactive Datin
the process by which the approximate age of an object is determined based on the amount of certain radioactive nuclides present.
Radioactive Tracers
radioactive atoms that are incorporated into substances so that movement of the substances can be followed by radiation detectors.
Nuclear Waste
must be contained, stored, and disposed of in a way that minimizes harm to the people or the environment.
Nuclear Fission
a very heavy nucleus splits into more stable nuclei of intermediate mass. Releases enormous amounts of energy.
Chain Reaction
a reaction in which the material that starts the reaction is also one of the products and can start another reaction.
Critical Mass
the minimum amount of nuclide that provides the number of neutrons needed to sustain a chain reaction.
Nuclear Reactors
use controlled-fission chain reactions to produce energy and radioactive nuclides.
Nuclear Power Plants
use energy as heat from nuclear reactors to produce electrical energy.
a radiation-absorbing material that is used to decrease exposure to radiation, especially gamma rays, from nuclear reactors.
Control Rods
neutron-absorbing rods that help control the reaction by limiting the number of free neutrons.
used to slow down the fast neutrons produced by fission.
Nuclear Fusion
low-mass nuclei combine to form a heavier, more stable nucleus.
Lise Meitner
helped to discover that “transuranes” were radioisotopes of known elements. She did not win the Nobel Prize due to wartime politics.
Categories: Nuclear Chemistry