96 Mo; atomic See also:

• WEIGHT

weight See also:

• 96 Mo; atomic weight MOLYBDENUM [symbol (0=16)]

MOLYBDENUM [See also:

• SYMBOL (Gr. o-uµ(3oXov, a sign)

symbol (0=16)]  a metallic chemical See also:

• ELEMENT (Lat. elementum)

element . The name is derived from Gr. poXui36os, See also:

• LEAD
• LEAD (pronounced iced)

lead, and was originally employed to denote many substances containing or resembling lead; ultimately the See also:

• TERM

term was applied to See also:

• GRAPHITE

graphite and to See also:

• MOLYBDENUM [symbol, Mo; atomic weight, 96 (0=16)]

molybdenum sulphide . The difference between these two latter substances was first pointed out by Cronstedt, and in 1778 C . See also:

• SCHEELE, KARL WILHELM (1742-1786)

Scheele prepared molybdic See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid from the sulphide . Molybdenum occurs in nature chiefly as the minerals See also:

• MOLYBDENITE

molybdenite (MoS2) and See also:

• WULFENITE

wulfenite (PbMoO4), and more rarely as molybdic ochre (MoO3) and ilsemannite; it also occurs in many See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron ores . The See also:

• METAL
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

metal may be obtained by See also:

• HEATING

heating the trioxide with See also:

• CARBON (symbol C, atomic weight 12)

carbon in the electric See also:

• FURNACE

furnace (H . See also:

• MOISSAN, HENRI (1852-1907)

Moissan, Comptes rendus, 1893, 116, p . 1225), or by the See also:

• GOLDSCHMIDT, HERMANN (1802-1866)

Goldschmidt method (See also:

• ROSENHEIM

Rosenheim and Braun, Zeit. anorg . Chem., 1905, p . 311) or by dissociating the tetra- and pentachloride in a graphite crucible with an electric current below 1330 (J . N . Pring and W .

See also:

• FIELDING, ANTHONY VANDYKE COPLEY (1787-1855)
• FIELDING, HENRY (1707-1754)
• FIELDING, WILLIAM STEVENS (1848– )

Fielding, Jour . Chem . See also:

• SOC

Soc., 1909, 95, p . 1497) . It forms a See also:

• GREY, CHARLES GREY, 2ND EARL (1764-1845)
• GREY, HENRY GREY, 3RD EARL (1802-1894)
• GREY, LADY JANE (1537-1554)
• GREY, SIR EDWARD
• GREY, SIR GEORGE (1812–1898)

grey coloured See also:

• POWDER (through O. Fr. puldre, modern poudre, from Lat. pulvis, pulveris, dust)

powder of specific gravity 9.oi; it is malleable, and not as hard as See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass . It is rapidly oxidized on heating to a temperature of 5oo°-600° C., and also when fused with See also:

• NITRE

nitre or See also:

• POTASSIUM [symbol K (from kalium), atomic weight 39.114 0=16)]

potassium chlorate . It is soluble in dilute nitric acid, and in concentrated sulphuric acid; in the latter See also:

• CASE
• CASE, JOHN (d. 1600)

case with the formation of a See also:

• BLUE (common in different forms to most European languages)

blue See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution which on heating becomes colourless, molybdenum trioxide being formed with the liberation of See also:

• SULPHUR

sulphur dioxide . Molybdenum combines with See also:

• OXYGEN (symbol 0, atomic weight 16)

oxygen to See also:

• FORM (Lat. forma)

form many oxides, the most important of which are : the monoxide, MoO.n (See also:

• H2O (combined)

H2O), the sesquioxide, Mo203, the dioxide, MoO2, and the trioxide, MOOS• Molybdenum monoxide, MoO.n(H2O), is a See also:

• BLACK
• BLACK, ADAM (1784-1874)
• BLACK, JEREMIAH SULLIVAN (1810–1883)
• BLACK, WILLIAM (1841-1898)

black powder obtained when the dichloride is boiled with concentrated potash solution . According to W . Muthmann and W . Nagel (Ber., 1898, 31, p . 2009), this See also:

• OXIDE

oxide does not exist, the reaction leading to the formation of an hydroxide according to the See also:

• EQUATION (from Lat. aequatio, aequare, to equalize)

equation: Mo3C14(OH)s + 4KHO + 3H2O = 3Mo(OH)3+4KBr{-3H .

Molybdenum sesquioxide, Mo203i a black See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

mass insoluble in acids, is formed by heating the corresponding hydroxide in vacuo, or by digesting the trioxide with See also:

• ZINC

zinc and hydrochloric acid . Molybdenum dioxide, MoO2, is formed by heating See also:

• SODIUM [symbol Na, from Lat. natrium; atomic weight 23.00 (0=16)]

sodium trimolybdate, Na2Mo3Ols, to redness in a current of See also:

• HYDROGEN [symbol H, atomic weight x-oo8 (0=16)]

hydrogen (L . Svanberg and H . See also:

• STRUVE, FRIEDRICH GEORG WILHELM (1793-1864)

Struve, Jour. prak . Chem., 1848, 44, p . 301), or by See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long See also:

• FUSION

fusion of a mixture of ammonium molybdate, potassium carbonate, and See also:

• BORON (symbol B, atomic weight I I)

boron trioxide (W . Muthmann, See also:

• ANN

Ann., 1887, 238, p . 114) . It forms quadratic prisms, having a See also:

• VIOLET

violet reflex and insoluble in boiling hydrochloric acid . Molybdenum trioxide, MoO3, is prepared by oxidizing the metal or the sulphide by heating them in See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air, or with nitric acid . It, is a See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white powder, which turns See also:

• PALE (through Fr. pal, from Lat. palms, a stake, for paglus, from the stem pag- of pangere, to fix; " pole " is from the same original source)

pale yellow on heating, and melts at a red See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat . It sublimes in small rhombic tables or needles, and is slightly soluble in See also:

• COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold See also:

• WATER

water, the solution possessing an acid reaction .

Several hydrated forms of the oxide are known, and a colloidal variety may be obtained by the See also:

• DIALYSIS (from the Gr. &0., through, Anew, to loosen)

dialysis of a strong hydrochloric acid solution of sodium molybdate . Molybdenum trioxide, like See also:

• CHROMIUM (symbol Cr. atomic weight 52.1)

chromium trioxide, is an acidic oxide, and forms salts known as molybdates . The normal molybdates show a tendency to pass into polymolybdates . The molybdates are also capable of combining with other oxides (such as See also:

• PHOSPHORUS (Gr. 4ws, light, sPEpety, to bear)

phosphorus and See also:

• ARSENIC (symbol As, atomic weight 75.0)

arsenic pentoxides) yielding very complex salts . The See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary ammonium molybdate, used as a test reagent for See also:

• PHOSPHATES

phosphates, is a See also:

• SALT (a common Teutonic word, cf. Dutch zout, Ger. Salz, Scand. salt; cognate with Gr. &Xs, Lat. sal)
• SALT, SIR TITUS, BART

salt of See also:

• COMPOSITION
• COMPOSITION (Lat. compositio, from componere, to put together)

composition (NH4)10MO12041; it has been examined physicochemically by J . See also:

• SAND
• SAND, GEORGE (1804-1876)

Sand and F . Eisenlohr (Abst . J.C.S., 1907, 1i. pp . 178, 179) . The molybdates may be recognized by the fact that they give a white precipitate on the addition of hydrochloric or nitric acids to their solutions, and that with reducing agents (zinc and sulphuric acid) they give generally a blue coloration which turns to a See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

green and finally to a See also:

• BROWN
• BROWN, CHARLES BROCKDEN (1771-181o)
• BROWN, FORD MADOX (1821-1893)
• BROWN, FRANCIS (1849- )
• BROWN, GEORGE (1818-188o)
• BROWN, HENRY KIRKE (1814-1886)
• BROWN, JACOB (1775–1828)
• BROWN, JOHN (1715–1766)
• BROWN, JOHN (1722-1787)
• BROWN, JOHN (1735–1788)
• BROWN, JOHN (1784–1858)
• BROWN, JOHN (1800-1859)
• BROWN, JOHN (1810—1882)
• BROWN, JOHN GEORGE (1831— )
• BROWN, ROBERT (1773-1858)
• BROWN, SAMUEL MORISON (1817—1856)
• BROWN, SIR GEORGE (1790-1865)
• BROWN, SIR JOHN (1816-1896)
• BROWN, SIR WILLIAM, BART
• BROWN, THOMAS (1663-1704)
• BROWN, THOMAS (1778-1820)
• BROWN, THOMAS EDWARD (1830-1897)
• BROWN, WILLIAM LAURENCE (1755–1830)

brown See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour . . Molybdenum combines with the halogen elements in varying See also:

• PRO

pro-portions, forming with See also:

• CHLORINE (symbol Cl, atomic weight 35`46 (0=16)

chlorine a di-, tr1-, tetra- and penta-chloride, and similar compounds with See also:

• BROMINE (symbol Br, atomic weight 79-96)

bromine and See also:

• IODINE (symbol I, atomic weight '26.92)

iodine . Molybdenum dichloride (MoC12)3 or C14Mo3C12 (chlormolybdenum chloride), is prepared (together with some tetrachloride) by heating the trichlonde in a stream of carbon dioxide (C .

W . Blomstrand, Jour. f. prak.Chem.,1857, 71, p . 449 ; 1861, 82, p . 433) . It is a yellow amorphous powder which is soluble in dilute alkalis, the solution on acidification giving an hydroxide, C14Mo3(OH)2, which is soluble in nitric acid, and does not give a reaction with See also:

• SILVER

silver nitrate . The molecular See also:

• WEIGHT

weight determinations of W . Muthmann and W . Nagel (Ber., 1898, 31, p . 2009) show the salt to possess the composition Mo3C16 . Molybdenum trichioride, MoC13, is obtained when the pentachloride is heated to a temperature of about 250° C. in a current of hydrogen . It forms red crusts, is insoluble in cold water, but is decomposed by boiling water . It is easily soluble in hot nitric acid .

Molybdenum pentachloride, MoCl5,. is obtained when molybdenum is gently heated in dry chlorine (L . P . Liechti and B . See also:

• KEMPE, JOHN (c. 1380-1454)

Kempe, Ann., 1873, 169, p . 345) . It is a dark-coloured crystalline solid which melts at 194° C. and boils at 268° C . It fumes in moist air and deliquesces gradually . It is occasionally used as a chlorine See also:

• CARRIER
• CARRIER, JEAN BAPTISTE (1956-1794)

carrier . It is soluble in See also:

• ABSOLUTE (Lat. absolvere, to loose, set free)

absolute See also:

• ALCOHOL

alcohol and in See also:

• ETHER, (C2H5)2O

ether . Molybdenum disulphide, MoS2, is found as the See also:

• MINERAL

mineral molybdenite, and may be prepared by heating the trioxide with sulphur or sulphuretted hydrogen . It is a black crystalline powder, resembling graphite in See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance . It is readily oxidized by nitric acid, and when strohgly heated in a current of hydrogen is reduced to the metallic See also:

• CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition .

Molybdenum trisulphide, MoS,, is obtained by saturating a solution of an alkaline molybdate with sulphuretted hydrogen and adding a mineral acid . It is a brown powder which on heating in air loses sulphur and leaves a See also:

• RESIDUE (through the French, from the Lat. residuum, a remainder, from residere, to remain)

residue of the disulphide . A tetrasulphide, MoS4, has also been described . Many varying values have been given for the atomic weight of molybdenum . J . J . See also:

• BERZELIUS, JONS JAKOB (1779-1848)

Berzelius (Pogg . Ann., 1826, 8, p . 23), by converting lead molybdate into lead nitrate, obtained the value 95.2 ;while J . B . A . See also:

• DUMAS, ALEXANDRE
• DUMAS, ALEXANDRE [" DUMAS FILS"] (1824-1895)
• DUMAS, GUILLAUME MATHIEU, COUNT (1753-1837)
• DUMAS, JEAN BAPTISTE ANDRE (1800-1884)

Dumas (Ann., 186o, 113, p .

32), by converting the trioxide Into the metal, obtained the value 95.65 . K . Seubert and W . See also:

• POLLARD, EDWARD ALBERT (1828–1872)

Pollard (Zeit. anorg . Chem., 1895, 8, p . 434) using this u cond method obtained the value 96.28; whilst E . F . See also:

• SMITH
• SMITH, ADAM (1723–1790)
• SMITH, ALEXANDER (183o-1867)
• SMITH, ANDREW JACKSON (1815-1897)
• SMITH, CHARLES EMORY (1842–1908)
• SMITH, CHARLES FERGUSON (1807–1862)
• SMITH, CHARLOTTE (1749-1806)
• SMITH, COLVIN (1795—1875)
• SMITH, EDMUND KIRBY (1824-1893)
• SMITH, G
• SMITH, GEORGE (1789-1846)
• SMITH, GEORGE (184o-1876)
• SMITH, GEORGE ADAM (1856- )
• SMITH, GERRIT (1797–1874)
• SMITH, GOLDWIN (1823-191o)
• SMITH, HENRY BOYNTON (1815-1877)
• SMITH, HENRY JOHN STEPHEN (1826-1883)
• SMITH, HENRY PRESERVED (1847– )
• SMITH, JAMES (1775–1839)
• SMITH, JOHN (1579-1631)
• SMITH, JOHN RAPHAEL (1752–1812)
• SMITH, JOSEPH, JR
• SMITH, MORGAN LEWIS (1822–1874)
• SMITH, RICHARD BAIRD (1818-1861)
• SMITH, ROBERT (1689-1768)
• SMITH, SIR HENRY GEORGE WAKELYN
• SMITH, SIR THOMAS (1513-1577)
• SMITH, SIR WILLIAM (1813-1893)
• SMITH, SIR WILLIAM SIDNEY (1764-1840)
• SMITH, SYDNEY (1771-1845)
• SMITH, THOMAS SOUTHWOOD (1788-1861)
• SMITH, WILLIAM (1769-1839)
• SMITH, WILLIAM (c. 1730-1819)
• SMITH, WILLIAM (fl. 1596)
• SMITH, WILLIAM FARRAR (1824—1903)
• SMITH, WILLIAM HENRY (1808—1872)
• SMITH, WILLIAM HENRY (1825—1891)
• SMITH, WILLIAM ROBERTSON (1846-'894)

Smith and P . See also:

• MAAS, JOSEPH (1847-1886)

Maas (Zeit. anorg . Chem., 1894, 5, p . 280), by heating pure sodium molybdate in hydrochloric acid and estimating the amount of sodium chloride formed, obtained the value 96.087 .