Cov Khoom Ntawm Molybdenum
| Atomic naj npawb | 42 |
| CAS nr | 7439-98-7 ib |
| Atomic loj | 95.94 ib |
| Melting point | 2620 ° C |
| Boiling point | 5560 ° C |
| Atomic ntim | 0,015 3 nm3 |
| Qhov ceev ntawm 20 ° C | 10.2g / cm³ |
| Crystal qauv | lub cev-center cubic |
| Lattice tas li | 0.3147 [nm] |
| Kev nplua nuj nyob rau hauv lub ntiaj teb crust | 1.2 [g/t] |
| Ceev lub suab | 5400 m / s (ntawm rt) (thin rod) |
| Thermal expansion | 4.8 µm / (m·K) (ntawm 25 ° C) |
| Thermal conductivity | 138 W / (m·K) |
| Hluav taws xob resistivity | 53.4 nΩ·m (ntawm 20 ° C) |
| Mohs hardness | 5.5 |
| Vickers hardness | 1400-2740 Mpa |
| Brinell hardness | 1370-2500 Mpa |
Molybdenum yog ib yam khoom siv nrog lub cim Mo thiab atomic tooj 42. Lub npe yog los ntawm Neo-Latin molybdaenum, los ntawm Ancient Greek Μόλυβδος molybdos, lub ntsiab lus txhuas, vim nws cov ores tsis meej pem nrog cov hlau lead. Molybdenum minerals tau paub thoob plaws hauv keeb kwm, tab sis lub ntsiab lus tau pom (hauv kev nkag siab ntawm kev sib txawv nws yog ib qho chaw tshiab los ntawm cov ntxhia ntsev ntawm lwm cov hlau) hauv xyoo 1778 los ntawm Carl Wilhelm Scheele. Cov hlau yog thawj zaug nyob rau hauv 1781 los ntawm Peter Jacob Hjelm.
Molybdenum tsis tshwm sim ib yam li cov hlau dawb hauv ntiaj teb; Nws tsuas pom muaj nyob hauv ntau lub xeev oxidation hauv cov zaub mov. Cov khoom dawb, cov hlau silvery nrog grey cam khwb cia, muaj qhov thib rau-siab tshaj plaws melting point ntawm txhua lub caij. Nws nkag tau yooj yim, ruaj khov carbides nyob rau hauv alloys, thiab vim li no feem ntau ntawm lub ntiaj teb no zus tau tej cov khoom (kwv yees li 80%) yog siv nyob rau hauv steel alloys, nrog rau high-zog alloys thiab superalloys.
Feem ntau cov molybdenum tebchaw muaj tsawg solubility nyob rau hauv dej, tab sis thaum molybdenum bearing minerals hu rau oxygen thiab dej, lub resulting molybdate ion MoO2-4 yog soluble heev. Kev lag luam, molybdenum tebchaw (kwv yees li 14% ntawm lub ntiaj teb tsim cov khoom) yog siv nyob rau hauv high-pressure thiab high-temperature daim ntaub ntawv raws li pigments thiab catalysts.
Molybdenum-cov kabmob enzymes yog nyob deb ntawm cov kab mob uas muaj ntau tshaj plaws rau kev rhuav tshem cov tshuaj lom neeg hauv atmospheric molecular nitrogen nyob rau hauv cov txheej txheem ntawm lom nitrogen fixation. Tsawg kawg yog 50 molybdenum enzymes tam sim no paub hauv cov kab mob, nroj tsuag, thiab tsiaj txhu, txawm hais tias tsuas yog cov kab mob thiab cyanobacterial enzymes koom nrog hauv kev kho nitrogen. Cov nitrogenases muaj molybdenum nyob rau hauv ib daim ntawv sib txawv ntawm lwm cov molybdenum enzymes, uas tag nrho cov muaj tag nrho oxidized molybdenum nyob rau hauv ib tug molybdenum cofactor. Cov ntau yam molybdenum cofactor enzymes no tseem ceeb heev rau cov kab mob, thiab molybdenum yog ib qho tseem ceeb rau lub neej nyob rau hauv tag nrho cov kab mob siab dua eukaryote, tab sis tsis nyob rau hauv tag nrho cov kab mob.
Lub cev muaj zog
Nyob rau hauv nws cov ntshiab daim ntawv, molybdenum yog ib tug silvery-grey hlau nrog ib tug Mohs hardness ntawm 5.5, thiab tus qauv atomic hnyav ntawm 95.95 g / mol. Nws muaj qhov melting point ntawm 2,623 ° C (4,753 ° F); Ntawm cov khoom tshwm sim, tsuas yog tantalum, osmium, rhenium, tungsten, thiab carbon muaj cov ntsiab lus melting ntau dua. Nws muaj ib qho qis tshaj coefficients ntawm thermal expansion ntawm cov khoom siv hlau. Lub zog tensile ntawm cov xov hlau molybdenum nce txog 3 zaug, los ntawm 10 mus rau 30 GPa, thaum lawv txoj kab uas hla poob ntawm ~ 50-100 nm mus rau 10 nm.
Cov khoom siv tshuaj
Molybdenum yog cov hlau hloov pauv nrog electronegativity ntawm 2.16 ntawm Pauling nplai. Nws tsis pom pom tshwm sim nrog oxygen lossis dej ntawm chav tsev kub. Tsis muaj zog oxidation ntawm molybdenum pib ntawm 300 ° C (572 ° F); oxidation ntau tshwm sim ntawm qhov kub siab tshaj 600 ° C, ua rau molybdenum trioxide. Zoo li ntau cov hlau hloov pauv hnyav dua, molybdenum qhia me ntsis inclination los tsim ib qho cation hauv cov kua dej, txawm hais tias Mo3 + cation paub nyob rau hauv kev tswj xyuas kom zoo.
Cov khoom kub ntawm Molybdenum
