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secret police

(Encyclopedia)secret police, policing organization operating in secrecy for the political purposes of its government, often with terroristic procedures. Many states, including Chile, Iran, Iraq, Israel, Romania,...

biography

(Encyclopedia)biography, reconstruction in print or on film, of the lives of real men and women. Together with autobiography—an individual's interpretation of his own life—it shares a venerable tradition, meeti...

atom

(Encyclopedia)CE5 Bohr-Rutherford atom CE5 Probability distribution of the electron in the hydrogen atom: A. Ground state B. Highly excited state atom [Gr.,=uncuttable (indivisible)], basic unit of matte...

chemistry

(Encyclopedia)chemistry, branch of science concerned with the properties, composition, and structure of substances and the changes they undergo when they combine or react under specified conditions. Organic chemi...

electricity

(Encyclopedia)CE5 Electrical and radio symbols electricity, class of phenomena arising from the existence of charge. The basic unit of charge is that on the proton or electron—the proton's charge is designate...

Nobel Prizes (table)

(Encyclopedia)Nobel Prizes

element

(Encyclopedia)CE5 element, in chemistry, a substance that cannot be decomposed into simpler substances by chemical means. A substance such as a compound can be decomposed into its constituent elements by means o...

Sierra Leone

(Encyclopedia)CE5 Sierra Leone sēĕrˈə lēōˈnē, lēōnˈ; sērˈə lēōn [key], officially Republic of Sierra Leone, republic (2015 est. pop. 5,879,000), 27,699 sq mi (71,740 sq km), W Africa. It is borde...

elementary particles

(Encyclopedia)CE5 elementary particles, the most basic physical constituents of the universe. The first subatomic particle to be discovered was the electron, identified in 1897 by J. J. Thomson. After the...

history

(Encyclopedia)history, in its broadest sense, is the story of humanity's past. It also refers to the recording of that past. The diverse sources of history include books, newspapers, printed documents, personal pap...