Columbia Encyclopedia

Search results

500 results found

thallium

(Encyclopedia)thallium thălˈēəm [key], metallic chemical element; symbol Tl; at. no. 81; interval in which at. wt. ranges 204.382–204.385; m.p. 303.5℃; b.p. about 1,457℃; sp. gr. 11.85 at 20℃; valence +...

tungsten

(Encyclopedia)tungsten tŭngˈstən [key] [Swed.,=heavy stone], metallic chemical element; symbol W; at. no. 74; at. wt. 183.84; m.p. about 3,410℃; b.p. 5,660℃; sp. gr. 19.3 at 20℃; valence +2, +3, +4, +5, or...

Scheele, Karl Wilhelm

(Encyclopedia)Scheele, Karl Wilhelm kärl vĭlˈhĕlm shāˈlə [key], 1742–86, Swedish chemist, b. Stralsund. He is known as the discoverer of many chemical substances. He was a pharmacist in Stockholm, in Uppsa...

Negishi, Ei-ichi

(Encyclopedia)Negishi, Ei-ichi, 1935–2021, Japanese chemist, b. Changchum, China, Univ. of Tokyo (B.Eng., 1958), Univ. of Pennsylvania (Ph.D...

isotope

(Encyclopedia)CE5 Isotopes of hydrogen isotope īˈsətōp [key], in chemistry and physics, one of two or more atoms having the same atomic number but differing in atomic weight and mass number. The concept of ...

germanium

(Encyclopedia)germanium jərmāˈnēəm [key] [from Germany], semimetallic chemical element; symbol Ge; at. no. 32; at. wt. 72.63; m.p. 937.4℃; b.p. 2,830℃; sp. gr. 5.323 at 25℃; valence +2 or +4. Pure german...

Crookes, Sir William

(Encyclopedia)Crookes, Sir William, 1832–1919, English chemist and physicist. After serving at the Radcliffe Observatory, Oxford, and teaching chemistry at Chester Training College, he retired to work in his own ...

lawrencium

(Encyclopedia)lawrencium, artificially produced radioactive chemical element; symbol Lr; at. no. 103; mass number of most stable isotope 262; m.p. about 1,627℃; b.p. and sp. gr. unknown; valence +3. Lawrencium is...

tennessine

(Encyclopedia)tennessine tĕnˈəsēn [key], artificially produced radioactive chemical element; symbol Ts; at. no. 117; mass number of most stable isotope 294; m.p., b.p., sp. gr., and valence unknown. Tennessine ...

titanium

(Encyclopedia)titanium tītāˈnēəm, tĭ– [key] [from Titan], metallic chemical element; symbol Ti; at. no. 22; at. wt. 47.867; m.p. 1,675℃; b.p. 3,260℃; sp. gr. 4.54 at 20℃; valence +2, +3, or +4. Titani...