Chapter 21 Vocabulary: Nuclear Chemistry

– 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
228
88 Ra (superscript=mass number, subscript is atomic number) is the same as radium-228.

the difference between the mass of an atom and the sum of the masses of its protons, neutrons, and electrons.

the energy released when a nucleus is formed from neutrons, or the amount of energy required to break apart the nucleus.

a theory that nucleons exist in different energy levels, or shells, in the nucleus.

the numbers of nucleons that represent completed nuclear shells (2, 8, 20, 28, 50, 82, 126).

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.

the spontaneous disintegration of a nucleus into a slightly lighter nucleus, accompanied by emission of particles, electromagnetic radiation, or both.

particles or electromagnetic radiation emitted from the nucleus during radioactive decay.

an unstable nucleus that undergoes radioactive decay.

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+.

an electron emitted from the nucleus during some kinds of radioactive decay (the atomic number increases by one, the mass number does not change).

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.

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).

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.

a series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is reached.

the heaviest nuclide of each decay series.

the nuclides produces by the decay of the parent nuclides.

bombardment of nuclei with charged and uncharged particles.

elements with more than 92 protons in their nuclei.

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.

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.

use exposure of film to measure the approximate radiation exposure of people working with radiation.

instruments that detect radiation by counting electrical pulses carried by gas ionized by radiation.

instruments that convert scintillating light to an electric signal for detecting radiation.

the process by which the approximate age of an object is determined based on the amount of certain radioactive nuclides present.

radioactive atoms that are incorporated into substances so that movement of the substances can be followed by radiation detectors.

must be contained, stored, and disposed of in a way that minimizes harm to the people or the environment.

a very heavy nucleus splits into more stable nuclei of intermediate mass. Releases enormous amounts of energy.

a reaction in which the material that starts the reaction is also one of the products and can start another reaction.

the minimum amount of nuclide that provides the number of neutrons needed to sustain a chain reaction.

use controlled-fission chain reactions to produce energy and radioactive nuclides.

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.

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.

low-mass nuclei combine to form a heavier, more stable nucleus.

helped to discover that “transuranes” were radioisotopes of known elements. She did not win the Nobel Prize due to wartime politics.