NOBELIUM

Inleiding

atoomgetal: 102
groep: Geen
atoomgewig: 259
tydperk: 7
CAS nommer: 10028-14-5

klassifikasie

Metal
metaal
metaalagtige
alkalimetaal
Alkali aard metaal
oorgangsmetaal
Chalcogen
halogeen
edelgas
Lanthanoid
Actinoid
Rare Earth Element
Platinumgroepmetaalverwante
transuraan
Geen stabiele isotope
Solied
Liquid
gas
Solied (voorspel)

beskrywing • Gebruike / Function

Nobelium was unambiguously discovered and identified in April 1958 at Berkeley by A. Ghiorso, T. Sikkeland, J. R. Walton, and G. T. Seaborg, who used a new double-recoil technique. A heavy-ion linear accelerator (HILAC) was used to bombard a thin target of curium (95% curium-244 and 4.5% curium-246) with carbon-12 ions to produce Element 102-254 according to the curium-246 (carbon-12, 4 neutrons) reaction. Earlier in 1957 workers of the U.S., Britain, and Sweden announced the discovery of an isotope of Element 102 with a 10-min half-life at 8.5 MeV, as a result of bombarding curium-244 with carbon-13 nuclei. On the basis of this experiment the name nobelium was assigned and accepted by the Commission on Atomic Weights of the International Union of Pure and Applied Chemistry. The acceptance of the name was premature, for both Russian and American efforts now completely rule out the possibility of any isotope of Element 102 having a half-life of 10 min in the vicinity of 8.5 MeV. Early work in 1957 on the search for this element, in Russia at the Kurchatov Institute, was marred by the assignment of 8.9 ± 0.4 MeV alpha radiation with a half-life of 2 to 40 sec, which was too indefinite to support claim to discovery. Confirmatory experiments at Berkeley in 1966 have shown the existence of Element 102-254 with a 55-s half-life, Element 102-252 with a 2.3-s half-life, and Element 102-257 with a 25-s half-life. Twelve isotopes are now recognized, one of which — Element 102-255 has a half-life of 3.1 min. In view of the discover’s traditional right to name an element, the Berkeley group, in 1967, suggested that the hastily given name nobelium, along with the symbol No, be retained. 1

Fisiese eienskappe

Smeltpunt:2*  827 °C = 1100.15 K = 1520.6 °F
Kookpunt:2
sublimasie Point:2 
Drie Point:2 
kritieke punt:2 
digtheid:   g/cm3

* - at 1 atm

elektronkonfigurasie

elektronkonfigurasie:  *[Rn] 7s2 5f14
Blok: f
Hoogste Besig energievlak: 7
valenselektrone: 2

kwantumgetalle:

n = 5
ℓ = 3
m = 3
ms = -½

binding

ionisasiepotensiaal   eV 3  kJ/mol  
ionisasiepotensiaal   eV 3  kJ/mol  
ionisasiepotensiaal   eV 3  kJ/mol  
1 6.65    641.6

termochemie

Spesifieke hitte: 
Termiese geleidingsvermoë: 10 (W/m)/K, 27°C 4
Verhit van Fusion: 
Hitte van verdamping: 
Toestand van materie Entalpie van vorming (ΔHf°)5 entropie (S°)5 Gibbs vrye energie (ΔGf°)5
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(g) 21.57 90.24888 50.347 210.651848 20.69 86.56696

isotope

nuklied Mis 6 Halflewe 6 kern Spin 6 bindingsenergie
248No 248.08660(32)# <2 μs 0+ 1,847.36 MeV
249No 249.08783(37)# 57(12) μs [54(+15-10) μs] 5/2+# 1,855.44 MeV
250No 250.08751(22)# 5.7(8) μs 0+ 1,863.51 MeV
251No 251.08901(19)# 0.78(2) s 7/2+# 1,871.58 MeV
252No 252.088977(14) 2.27(14) s 0+ 1,879.65 MeV
253No 253.09068(11)# 1.62(15) min (9/2-)# 1,878.41 MeV
254No 254.090955(19) 51(10) s 0+ 1,886.48 MeV
255No 255.093241(11) 3.1(2) min (1/2+) 1,894.55 MeV
256No 256.094283(8) 2.91(5) s 0+ 1,902.62 MeV
257No 257.096877(23) 25(2) s (7/2+) 1,910.69 MeV
258No 258.09821(22)# 1.2(2) ms 0+ 1,918.76 MeV
259No 259.10103(11)# 58(5) min (9/2+)# 1,917.52 MeV
260No 260.10264(22)# 106(8) ms 0+ 1,925.59 MeV
261No 261.10575(32)# 3# h 3/2+# 1,933.66 MeV
262No 262.10730(48)# ~5 ms 0+ 1,941.73 MeV
263No 263.11055(53)# 20# min 1,940.49 MeV
264No 264.11235(69)# 1# min 0+ 1,948.56 MeV
Waardes gemerk # is nie suiwer afgelei van eksperimentele data, maar ten minste gedeeltelik uit sistematiese tendense. Draai met 'n swak werkstuk argumente is ingesluit in hakies. 6

reaksies

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Bronne

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(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
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