Science / Chemistry / Nuclide: An atom or ion with a specified mass number and atomic number. For example, uranium-235 and carbon-14 are nuclides.

Nuclide Symbol

Science / Chemistry / Nuclide Symbol: A symbol for an nuclide that contains the mass number as a leading superscript and the atomic number as a leading subscript. For ions, the ionic charge is given as a trailing superscript. For example, MORE


Health / Disease / Radionuclide: Any radioactive isotope (form) of any element. MORE

Atomic Weight

Science / Biology / Atomic Weight: The sum of the weights of an atoms protons and neutrons, the atomic weight differs between isotopes of the same element. MORE

Public Health Hazard

Health / Disease / Public Health Hazard: A category used in ATSDR's public health assessments for sites that pose a public health hazard because of long-term exposures (greater than 1 year) to sufficiently high levels of hazardous substances MORE


Science / Chemistry / Isobar: 1. A contour line that corresponds to values measured at identical pressures. For example, curves on a plot of gas volumes measured at different temperatures in an open container are isobars. 2. Nucli MORE

Mass Number

Science / Chemistry / Mass Number: The total number of protons and neutrons in an atom or ion. In nuclide symbols the mass number is given as a leading superscript. In isotope names (e. G. Carbon-14, sodium-23) the mass number is the n MORE