a series of elements whose atomic weights were known
41Copley Medal — The Copley Medal awarded to Mendeleev in 1905 …
42Chinese mathematics — Mathematics in China emerged independently by the 11th century BC.[1] The Chinese independently developed very large and negative numbers, decimals, a place value decimal system, a binary system, algebra, geometry, and trigonometry. Many[who?]… …
43gas — gasless, adj. /gas/, n., pl. gases, v., gassed, gassing. n. 1. Physics. a substance possessing perfect molecular mobility and the property of indefinite expansion, as opposed to a solid or liquid. 2. any such fluid or mixture of fluids. 3. any… …
44harbours and sea works — Introduction harbour also spelled harbor any part of a body of water and the manmade structures surrounding it that sufficiently shelters a vessel from wind, waves, and currents, enabling safe anchorage or the discharge and loading of… …
45Sapphire & Steel — Sapphire and Steel have been assigned. The final frame of the title sequence. Format Science fiction, drama Created by …
46technology, history of — Introduction the development over time of systematic techniques for making and doing things. The term technology, a combination of the Greek technē, “art, craft,” with logos, “word, speech,” meant in Greece a discourse on the arts, both… …
47History of timekeeping devices — For thousands of years, devices have been used to measure and keep track of time. The current sexagesimal system of time measurement dates to approximately 2000 BC, in Sumer. The Ancient Egyptians divided the day into two 12 hour periods, and… …
48coordination compound — Chem. complex (def. 10). Also called coordination complex. * * * ▪ chemistry Introduction any of a class of substances with chemical structures in which a central metal atom is surrounded by nonmetal atoms or groups of atoms, called ligands… …
49Time in physics — In physics, the treatment of time is a central issue. It has been treated as a question of geometry. One can measure time and treat it as a geometrical dimension, such as length, and perform mathematical operations on it. It is a scalar quantity… …
50European Union — 1. an association of European nations formed in 1993 for the purpose of achieving political and economic integration. Formerly known as the European Economic Community, the European Union s member states are Austria, Belgium, Denmark, Finland,… …
