Nuclear Chemistry Review

Process by which nuclei of unstable isotopes emit radiation

In the nucleus of an atom, there are protons (p+) and neutrons (n0)

An unstable isotope that is subject to radioactive decay

The breaking down of an unstable atomic nucleus to produce radiation and a more stable nucleus of a different element

Energy given off by the nucleus in the form of penetrating rays and particles

Radioactive decay is spontaneous and does not require input of energy

The changing of 1 element into another element by radioactive decay

The stability of a nucleus depends on ratio of neutrons to protons; too many or too few neutrons relative to protons makes it unstable

Elements with atomic number 84+ are considered to be radioactive; elements with odd mass numbers of protons and neutrons are also radioactive

Light elements where the ratio of n0 to p+ is 1 are considered to be stable; elements with even # p+ and n0 are considered more stable than their odd counterparts

An atom of an element with a different mass number

Alpha Decay, Beta Decay, Gamma Radiation, Positron, Electron Capture

The first type of discovered decay; yields a Helium nucleus; is common for heavier elements; decreases mass # of daughter nuclide by 4, and its atomic # by 2; if need be, decreases neutrons, increases protons

Neutral charge; only the helium nucleus is emitted; 4 mass #, +2 atomic #

Increases atomic # of daughter nuclide by 1, while leaving mass # intact; produces and ejects an electron; produces a proton; if need be, increases neutrons, decreases protons

No mass #, -1 atomic #

Particle with an electron’s mass, but a proton’s charge; has no mass number, but +1 atomic #

The decreasing of a parent isotope’s atomic #

The capturing of an inner electron by the nucleus of its own atom; forms a nucleus; causes decrease of atomic #

Allows nucleus to rid itself of excess energy for stabilization

The force holding all nuclear particles close together; effective only at minuscule distances; opposes electrostatic forces that would normally separate particles of like charges

The hypothetical line where the # of neutrons divided by the atomic # is 1; elements with atomic # of 20 and below are close to this line

This ratio determines the radioactive decay that an element undergoes

The time it takes 1/2 of the nuclei of a radioactive substance to decay

N =N0 (1/2) n
where n = # ½ lives that have passed, No is initial amount, N = remaining amount (n= t/T, t =elapsed time, T= duration of half-life)

Transmutation can occur by either decay or bombardment

Hitting an atom with a particle to see what happens

Elements with atomic numbers above 92; all are man-made, radioactive; Np & Pu first artificial elements – produced in 1940s; since that time, over 20 artificial elements produced in particle accelerators or nuclear reactors

A series of radioisotopes produced by successive radioactive decay until a stable isotope is reached

The heaviest radioisotope of each decay series

The radioisotopes produced by the decay of the parent nuclide

Radioactive decay rates are measured in half-lives; half-lives can range from nanoseconds to billions of years

When the nucleus of a very heavy atom splits into more stable nuclei of smaller mass; the separation of atoms; releases nuclear energy; neutron collides with nucleus, splitting the nucleus and releasing nuclear energy; this process releases a great deal of energy (E=mc2), and is the basis for nuclear reactors and some atomic weapons

Adding a neutron to a stable nucleus increases the volume of the nucleus; this decreases the nuclear strong force, increasing the activity of nuclear particles

Bonding of atoms; the process by which we get atoms; smaller atomic nuclei are joined, or fused, together to form a nucleus of greater mass; in general, fusion reactions release much larger quantities of energy than fission reactions

Generating electricity, nuclear bombs

Iron resists fusion; iron is the most stable element, meaning its nucleus releases the lowest amount of energy; as such, iron cannot be fused into heavier elements

This occurs when the material that starts the reaction is also one of the products of the reaction and can start another reaction with fissionable material

A sample of fissionable material must have sufficient mass to in order for a chain reaction to occur and be sustained

Slowing down the n so that they are captured by the material in order to continue the reaction – if the n are moving too fast, they will pass through the nucleus and not be absorbed, water or carbon are used as moderators

Trapping the slower-moving n before they hit fissionable material – requires control rods, often made of Cd

The net conversion of hydrogen nuclei to helium nuclei releases so much energy because energy in a star is released with a velocity equal to the square of the speed of light

When supernova detonation, the explosion of a supernova, commences, the dense core, which following the collapse of the star became solely comprised of neutrons, reflects the outer layers of the star that fall unto the core; the resulting shock waves are so grand that they force nuclear particles to bond, creating heavy elements