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atomic clock

(Encyclopedia)atomic clock, electric or electronic timekeeping device that is controlled by atomic or molecular oscillations. A timekeeping device must contain or be connected to some apparatus that oscillates at a...

atomic energy

(Encyclopedia)atomic energy: see nuclear energy. ...

concentration

(Encyclopedia)concentration, in chemistry, measure of the relative proportions of two or more quantities in a mixture. The concentration of a solute is very important in studying chemical reactions because it deter...

periodic law

(Encyclopedia)periodic law, statement of a periodic recurrence of chemical and physical properties of the elements when the elements are arranged in order of increasing atomic number. Such an arrangement in the for...

Atomic Energy Commission

(Encyclopedia)Atomic Energy Commission (AEC), former U.S. government commission created by the Atomic Energy Act of 1946 and charged with the development and control of the U.S. atomic energy program following Worl...

atomic force microscope

(Encyclopedia)atomic force microscope (AFM), device that uses a spring-mounted probe to image individual atoms on the surface of a material, first developed by Gerd Binnig in 1986. Unlike the scanning tunneling mic...

atomic mass unit

(Encyclopedia)atomic mass unit or amu, in chemistry and physics, unit defined as exactly 1⁄12 the mass of an atom of carbon-12, the isotope of carbon with six protons and six neutrons in its nucleus. One amu is e...

Periodic Table of the Elements: Actinium

(Encyclopedia)Periodic Table of the Elements: Actinium ...

Periodic Table of the Elements: Aluminum

(Encyclopedia)Periodic Table of the Elements: Aluminum ...

Periodic Table of the Elements: Americium

(Encyclopedia)Periodic Table of the Elements: Americium ...