H. Steffen Peiser
Contributor
LOCATION: Rockville, MD, United States
Consultant. Chief, Office of International Relations, National Bureau of Standards, U.S. Department of Commerce, Washington, D.C., 1969–79. Author of X-Ray Diffraction by Polycrystalline Materials.
Primary Contributions (1)
Atomic weight, ratio of the average mass of a chemical element’s atoms to some standard. Since 1961 the standard unit of atomic mass has been one-twelfth the mass of an atom of the isotope carbon-12. An isotope is one of two or more species of atoms of the same chemical element that have different…
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