MENDELEVIO

introduzione

Numero atomico: 101
Gruppo: Nessuna
Peso atomico: 258
Periodo: 7
Numero CAS: 7440-11-1

Classificazione

Metallo
Metalloide
simile a metallo
metallo alcalino
Alkali terroso
Metallo di transizione
calcogeno
alogena
Gas nobile
Lanthanoid
Actinoid
Terre rare
Platinum Metal Group
transuranici
Non ci sono isotopi stabili
Solido
Liquido
Gas
Solido (previsto)

Descrizione • Usi / Funzione

Mendelevium, the ninth transuranium element of the actinide series to be discovered, was first identified by Ghiorso, Harvey, Choppin, Thompson, and Seaborg early in 1955 as a result of the bombardment of the isotope einsteinium-253 with helium ions in the Berkeley 60-inch cyclotron. The isotope produced was mendelevium-256, which has a half-life of 78 min. This first identification was notable in that mendelevium-256 was synthesized on a one-atom-at-a-time basis. Sixteen isotopes and isomers are now recognized. mendelevium-258 has a half-life of 51.5 days. This isotope has been produced by the bombardment of an isotope of einsteinium with ions of helium. It now appears possible that eventually enough mendelevium-258 can be made so that some of its physical properties can be determined. Mendelevium-256 has been used to elucidate some of the chemical properties of mendelevium in aqueous solution. Experiments seem to show that the element possesses a moderately stable dipositive (II) oxidation state in addition to the tripositive (III) oxidation state,which is characteristic of actinide elements. 1

Proprietà fisiche

Punto di fusione:2*  827 °C = 1100.15 K = 1520.6 °F
Punto di ebollizione:2
sublimazione Point:2 
Triple Point:2 
Punto critico:2 
Densità:   g/cm3

* - at 1 atm

configurazione elettronica

configurazione elettronica:  *[Rn] 7s2 5f13
Bloccare: f
Più alto livello di energia Occupato: 7
Elettroni di valenza: 2

numeri quantici:

n = 5
ℓ = 3
m = 2
ms = -½

bonding

potenziale di ionizzazione   eV 3  kJ/mol  
potenziale di ionizzazione   eV 3  kJ/mol  
potenziale di ionizzazione   eV 3  kJ/mol  
1 6.58    634.9

isotopi

nuclide Massa 4 Metà vita 4 spin nucleare 4 Energia di legame
245Md 245.08083(35)# 0.90(25) ms (1/2-)# 1,823.93 MeV
246Md 246.08189(35)# 1.0(4) s 1,832.00 MeV
247Md 247.08164(35)# 1.12(22) s 1/2-# 1,840.08 MeV
248Md 248.08282(26)# 7(3) s 1,848.15 MeV
249Md 249.08301(24)# 24(4) s (7/2-) 1,856.22 MeV
250Md 250.08442(32)# 52(6) s 1,864.29 MeV
251Md 251.08484(22)# 4.0(5) min 7/2-# 1,872.36 MeV
252Md 252.08656(21)# 2.3(8) min 1,880.43 MeV
253Md 253.08728(22)# 12(8) min [6(+12-3) min] 7/2-# 1,888.50 MeV
254Md 254.08966(11)# 10(3) min (0-) 1,896.58 MeV
255Md 255.091083(7) 27(2) min (7/2-) 1,895.33 MeV
256Md 256.09406(6) 77(2) min (1-) 1,903.40 MeV
257Md 257.095541(3) 5.52(5) h (7/2-) 1,911.47 MeV
258Md 258.098431(5) 51.5(3) d (8-)# 1,919.55 MeV
259Md 259.10051(22)# 1.60(6) h 7/2-# 1,918.30 MeV
260Md 260.10365(34)# 27.8(8) d 1,926.37 MeV
261Md 261.10572(70)# 40# min 7/2-# 1,934.44 MeV
262Md 262.10887(63)# 3# min 1,942.52 MeV
I valori assegnati # non sono puramente derivati ​​da dati sperimentali, ma almeno parzialmente da tendenze sistematiche. Gira con argomenti di assegnazione deboli sono racchiusi tra parentesi. 4

Abbondanza

Informazioni sulla sicurezza


Scheda di sicurezza - ACI Alloys, Inc.

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Link esterno:

fonti

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:19.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(7) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).