Columbia Encyclopedia

(Encyclopedia) xenon zēˈnŏn [key] [Gr.,=strange], gaseous chemical element; symbol Xe; at. no. 54; at. wt. 131.293; m.p. −111.9℃; b.p. −107.1℃; density 5.86 grams per liter at STP; valence usually 0. Xeno...

(Encyclopedia) actinium ăktĭnˈēəm [key] [Gr.,=like a ray], radioactive chemical element; symbol Ac; at. no. 89; mass number of most stable isotope 227; m.p. about 1,050℃; b.p. 3,200℃±300℃; sp. gr. 10.07;...

(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...

(Encyclopedia)  West, Kanye Omari, 1977- , African American rapper, b. Atlanta (some sources give Douglasville), Al. West’s father, Ray, was a Black Panther who ...

(Encyclopedia) dark energy, repulsive force that opposes the self-attraction of matter (see gravitation) and causes the expansion of the universe to accelerate. The search for dark energy was triggered by the discov...

(Encyclopedia) Jones, Quincy (Quincy Delight Jones, Jr.), 1933–, African-American musician, composer, bandleader, and music executive, b. Chicago. Jones played trumpet and sang gospel growing up, and studied brief...

(Encyclopedia) Teller, Edward, 1908–2003, American physicist, b. Budapest, Hungary, Ph.D. Univ. of Leipzig, 1930, where he studied under Werner Heisenberg. Fleeing the Nazis, he came to the United States in 1935 a...

(Encyclopedia) Geiger counter or Geiger-Müller (G-M) counter gīˈgər-mŭlˈər, –myo͞oˈlər [key], instrument for the detection and quantitative determination of ionizing radiation such as the alpha and beta ...

(Encyclopedia) black hole, in astronomy, celestial object of such extremely intense gravity that it attracts everything near it and in some instances prevents everything, including light, from escaping. The term was...

(Encyclopedia) muckrakers, name applied to American journalists, novelists, and critics who in the first decade of the 20th cent. attempted to expose the abuses of business and the corruption in politics. The term d...