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gadolinium

(Encyclopedia)gadolinium gădəlĭnˈēəm [key], metallic chemical element; symbol Gd; at. no. 64; at. wt. 157.25; m.p. 1,312℃; b.p. 3,233℃; sp. gr. 7.898 at 25℃; valence +3. Gadolinium is a malleable, ducti...

neodymium

(Encyclopedia)neodymium nēˌōdĭmˈēəm [key], metallic chemical element; symbol Nd; at. no. 60; at. wt. 144.242; m.p. about 1,021℃; b.p. about 3,068℃; sp. gr. 7.004 at 20℃; valence +3. Neodymium is a lust...

praseodymium

(Encyclopedia)praseodymium prāˌzēōdĭmˈēəm, –sēō– [key] [Gr., =green twin], metallic chemical element; symbol Pr; at. no. 59; at. wt. 140.90765; m.p. 931℃; b.p. 3,512℃; sp. gr. about 6.8; valence +...

protactinium

(Encyclopedia)protactinium prōˌtăktĭnˈēəm [key], radioactive chemical element; symbol Pa; at. no. 91; mass number of most stable isotope 231; m.p. greater than 1,600℃; b.p. 4,026℃; sp. gr. 15.37 (calcula...

organic chemistry

(Encyclopedia)organic chemistry, branch of chemistry dealing with the compounds of carbon. While it is only the fourteenth most common element on earth, carbon forms by far the greatest number of different compound...

Plücker, Julius

(Encyclopedia)Plücker, Julius yo͞oˈlyo͝os plüˈkər [key], 1801–68, German mathematician and physicist. He became professor of mathematics (1836) and of physics (1847) at the Univ. of Bonn. He is known for h...

nickel

(Encyclopedia)nickel, metallic chemical element; symbol Ni; at. no. 28; at. wt. 58.6934; m.p. about 1,453℃; b.p. about 2,732℃; sp. gr. 8.902 at 25℃; valence 0, +1, +2, +3, or +4. Nickel is a hard, malleable, ...

valence, in chemistry

(Encyclopedia)valence, combining capacity of an atom expressed as the number of single bonds the atom can form or the number of electrons an element gives up or accepts when reacting to form a compound. Atoms are c...

sodium chloride

(Encyclopedia)sodium chloride, NaCl, common salt. Salt is important in many ways. It is an essential part of the diet of both humans and animals and is a part of most animal fluids, such as blood, sweat, and te...