Physical Science 13.3-13.4

particles or electromagnetic waves given off when an atomic nucleus breaks up or undergoes a change

any substance that is unstable (and thus likely to produce radiation)

the breakup or change of an atomic nucleus from a higher-energy state to a lower-energy state

the length of time required for one-half of an original substance to decay into a new substance

radioactive decay that occurs when an unstable atom ejects a clump of two protons and two neutrons (an alpha particle)

radioactive decay that occurs when a neutron in an atom’s nucleus changes into a proton

radioactive decay that occurs when an excited nucleus releases energy without a change in the number of protons or neutrons

nuclear radiation that can harm living things by disrupting the chemical processes within cells’ includes alpha particles

the process whereby a heavy nucleus is split into several pieces by bombarding it with neutrons

the situation in which free neutrons released by nuclear fission cause other atoms to undergo nuclear fission and release more neutrons

the minimum amount of fissionable material that must be present for a chain reaction to occur

a device that works by initiating an uncontrolled nuclear fission chain reaction

a device that harnesses controlled fission to produce useful energy

a nuclear reactor that recycles spent nuclear fuel to produce more than it uses

the process of combining two nuclei to form a heavier nucleus and thereby releasing energy

a weapon that uses nuclear fusion to release a tremendous amount of energy

any of the electrons in the outer (valance) shell of an atom

the rule stating that an atom tends to react in a way that fills its valence shell with eight electrons

the law that states that elements show regular and repeating or periodic properties when they are arranged by their increasing atomic numbers

a table of the elements arranged by atomic number and number of valence electrons

a row on the periodic table

a column on the periodic table

any of the group of elements that are typically hard dense shiny solids are good conductors of what and electricity and have high melting points

any of the group of elements that are typically poor conductors of electricity and heat