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niobium

(Encyclopedia)niobium nīōˈbēəm [key], metallic chemical element; symbol Nb; at. no. 41; at. wt. 92.90638; m.p. about 2,468℃; b.p. 4,742℃; sp. gr. 8.57 at 20℃; valence +2, +3, +4, or +5. Niobium is a rare...

Nobel, Alfred Bernhard

(Encyclopedia)Nobel, Alfred Bernhard älˈfrĕd bĕrnˈhärd nōbĕlˈ [key], 1833–96, Swedish chemist and inventor. Educated in St. Petersburg, Russia, he traveled as a youth and returned to St. Petersburg in 18...

planetary science

(Encyclopedia)planetary science or planetology, study of planets and planetary systems as a whole. Planetary science applies the theories and methods of traditional disciplines such as astronomy, geology, physics, ...

polarography

(Encyclopedia)polarography pōˌlərŏgˈrəfē [key], in chemistry, method for analyzing the composition of a dilute electrolytic solution (see electrolyte). Two electrodes are placed in the solution: One has a fi...

carbonated beverage

(Encyclopedia)carbonated beverage, an effervescent drink that releases carbon dioxide under conditions of normal atmospheric pressure. Carbonation may occur naturally in spring water that has absorbed carbon dioxid...

carbonyl group

(Encyclopedia)carbonyl group kärˈbənĭl [key], in chemistry, functional group that consists of an oxygen atom joined by a double bond to a carbon atom. The carbon atom is joined to the remainder of the molecule ...

Weizmann, Chaim

(Encyclopedia)Weizmann, Chaim khīmˈ vītsˈmän [key], 1874–1952, scientist and Zionist leader, first president (1948–52) of Israel, b. Russia, grad. Univ. of Freiburg, 1899. He lectured in chemistry at the U...

Rush, Benjamin

(Encyclopedia)Rush, Benjamin, 1745?–1813, American physician, signer of the Declaration of Independence, b. Byberry (now part of Philadelphia), Pa., grad. College of New Jersey (now Princeton, 1760), M.D. Univ. o...

biology

(Encyclopedia)biology, the science that deals with living things. It is broadly divided into zoology, the study of animal life, and botany, the study of plant life. Subdivisions of each of these sciences include cy...

zero

(Encyclopedia)zero, that number which, when added to any number, leaves the latter unchanged; its symbol is 0. The introduction of zero into the decimal system was the most significant achievement in the developmen...