number
[num´ber] a symbol, as a figure or word, expressive of a certain value or a specified quantity determined by count.
atomic number (Z) a number expressive of the number of protons in an atomic nucleus, or the positive charge of the nucleus expressed in terms of the electronic charge.
Avogadro's number (
N) (
NA) the number of molecules in one mole of a substance: 6.023 × 10
23. Called also
Avogadro's constant.
CT number the density assigned to a
voxel in a
CAT scan on an arbitrary scale on which air has a density −1000; water, 0; and compact bone +1000. See also
hounsfield unit.
mass number (A) the number of nucleons (protons plus neutrons) in the atom of a nuclide; generally indicated by a superscript preceding the symbol of a chemical element (e.g., 131I), denoting a specific isotope.
oxidation number a number assigned to each atom in a molecule or ion that represents the number of electrons theoretically gained (positive oxidation numbers) or lost (negative numbers) in converting the atom to the elemental form.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
Z
Symbol for: 1. Atomic number.
2. Aza–a nucleoside substitite.
3. Glutamic acid and glutamine.
4. Impedance.
5. Drug slang A street term for 1 ounce–
28 g. of heroin.
6. Net charge.
7. Proton number.
8. Zone.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.