CHEM 24

Nucleus

The extremely small, positively charged dense center of an atom

Wilhelm Roentgen

Found that invisible rays were emitted when electrons bombarded the surface of certain materials

X-rays

High energy emissions that caused photographic plates to darken

Henri Becquerel

Was studying minerals that emit light after being exposed to sunlight

Phosphorescence

Minerals that emit light after being exposed to sunlight

Chemical reactions

Occur when bonds are broken and formed

Nuclear reactions

Occur when nuclei combine split, and emit radiation

Marie Curie

Named the process by which materials give off such rays

Radioactivity

The process Marie Curie named for materials emitting rays

Radiation

The rays and particles emitted by a radioactive source

Radioisotopes

Isotopes of atoms with unstable nuclei

Ernest Rutherford

Identified alpha, beta, and gamma radiation

Alpha particle

Has the same composition as a helium nucleus

Beta particle

A very fast-moving electron that is emitted when a neutron in an unstable nucleus converts intro a proton

Gamma rays

Are photons, which are high-energy (short wavelength) electromagnetic radiation

x-rays

Are a form of high-energy electromagnetic radiation that are not produced by radioactive sources

Penetrating power

The ability of radiation to pass through matter

Transmutation

The conversion of an element into another by radioactive decay

nucleons

Protons and neutrons

Strong nuclear force

Acts on subatomic particles close together, overcoming repulsion

Electrostatic force

Acts between two charged particles

Band of stability

The area on the graph where stable nuclei are found

beta decay

A radioistope that lies above the band of stability is unstable because it has too many neutrons relative to its number of protons

unstable

Spontaneously radioactive

alpha decay

All nuclei with more than 82 protons are radioactive and decay spontaneously

positron emission

A radioactive decay process that involves the emission of a positron from a nucleus

positron

A particle with the same mass as an electron but opposite charge

electron capture

Occurs when the nucleus of an atom draws in a surrounding electron, usually one from the lowest energy level

radioactive decay series

A series of nuclear reactions that begins with an unstable nucleus and results in the formation of a stable nucleus

Half-life

The time for half of a radioisotope’s nuclei to decay

radiochemical dating

The process of determining the age of an object by measuring the amount of a certain radioisotope remaining in that object

Carbon dating

Used to measure the age of artifacts from living organisms

Transuranium elements

The elements following uranium in the periodic table (element 93+)

Einstein’s equation

States that any reaction produces or consumes energy due to a loss of gain in mass

Mass defect

The difference in mass between a nucleus and its nucleons

Nuclear fission

The splitting of a nucleus into fragments

Critical mass

A sample massive enough to sustain a chain reaction

breeder reactors

Reactors able to produce more fuel than they use

Nuclear fusion

The combining of atomic nuclei

thermonuclear reactions

Fusion reactions are also known as

induced transmutation

The bombardment of nuclei with particles in order to create new elements

Ionizing radiation

Radiation energetic enough to ionize matter

Geiger counter

Used to detect and measure radiation levels

Radiotracer

A radioscope emitting non-ionizing radiation to signal substances

Dose of radiation

Refers to the amount of radiation absorbed from a source