LOTS 8: Nuclear Changes

Mr. P, Physical Science

Alpha ParticleLargest radioactive particle emitted during nuclear decay; it is positively charged and is also represented as a helium nucleus, 4He

α

Symbol meaning “alpha particle”

Average Atomic MassMean mass of the most stable isotopes for an element that is often rounded, then the number of protons is subtracted from it to find the number of neutrons in that atom

Beta ParticleSmallest radioactive particle emitted during nuclear decay; is it negatively charged because a neutron is broken into a proton, which stays in the nucleus, and electron, which leaves

β

Symbol meaning “beta particle”

Emit

To give off; unstable nuclei do this in order to try and become stable

FissionProcess of forcing one large, usually unstable, nucleus to break apart in order to release energy; this can result in a chain reaction, giving off massive amounts of energy and leaving behind radioactive nuclear waste

Fusion

Process of forcing two smaller nuclei to combine into one larger nucleus, which releases energy

Gamma RadiationHigh-level (dangerous) radiation given off by radioactive nuclei that changes the energy level of the isotope and not its mass

γSymbol meaning “gamma radiation”

Half-life

The amount of time it takes for half of a sample of unstable isotopes to decay

Hyphen Notation

Expression of an isotope that shows the name and mass number, separated by a hyphen

Neutron EmissionThis occurs during fission and fusion; a neutron is given off from the reaction and is able to affect other isotopes when it combines with a nucleus to increase its mass by 1 amu

Nuclear Decay

Process the nucleus undergoes by giving off radiation in order to become stable

Nuclear Radiation

Term describing all the particles and energy emitted during nuclear decay, fission, or fusion

Nuclear SymbolExpression of an isotope that shows the mass number (top left), the atomic number (bottom left), and the element’s chemical symbol

Nuclear WasteRadioactive isotopes left over after fission that cannot be broken down to release any more energy; this give off nuclear radiation and is very hazardous to organisms

Radioactivity

Tendency of unstable nuclei to break down in order to become stable

Stable Nucleus

A nucleus that does not decay because it has the proper proportions of protons and neutrons

Unstable NucleusA nucleus that has too much mass as compared to the average atomic mass of the “healthy” isotope, usually found on the Periodic table; usually heavier than lead, Pb