邯郸有什么大学:锎是什么？价值？作用？

Wikipedia
californium
98 berkelium ← californium → einsteinium
Dy
↑
Cf
↓
(Uqo)
periodic table

General
Name, Symbol, Number californium, Cf, 98
Chemical series actinides
Group, Period, Block n/a, 7, f
Appearance unknown, probably silvery
white or metallic gray
Atomic mass (251) g/mol
Electron configuration [Rn] 5f10 7s2
Electrons per shell 2, 8, 18, 32, 28, 8, 2
Physical properties
Phase solid
Density (near r.t.) 15.1 g/cm³
Melting point 1173 K
(900 °C, 1652 °F)
Atomic properties
Electronegativity 1.3 (Pauling scale)
Ionization energies 1st: 608 kJ/mol
Miscellaneous
CAS registry number 7440-71-3
Notable isotopes
Main article: Isotopes of californium iso NA half-life DM DE (MeV) DP
248Cf syn 333.5 d SF - -
α 6.361 244Cm
249Cf syn 351 y SF - -
α 6.295 245Cm
250Cf syn 13.08 y α 6.128 246Cm
SF - -
251Cf syn 898 y α 6.176 247Cm
252Cf syn 2.645 y α 6.217 248Cm
SF - -
253Cf syn 17.81 d β- 0.285 253Es
α 6.124 249Cm
254Cf syn 60.5 d SF - -
α 5.926 250Cm

References
Californium is a synthetic element in the periodic table that has the symbol Cf and atomic number 98. A radioactive transuranic element, californium has very few uses and was discovered by bombarding curium with alpha particles (helium ions).

Notable characteristics
Weighable amounts of californium make it possible to determine some of its properties using macroscopic quantities.

252Cf (2.6 year half-life) is a very strong neutron emitter and is thus extremely radioactive and harmful (one microgram spontaneously emits 170 million neutrons per minute). The decay of 254Cf (55-day half-life) may have been detected through telescopes in supernovae remnants. 249Cf is formed from the beta decay of 249Bk and most other californium isotopes are made by subjecting berkelium to intense neutron radiation in a nuclear reactor.

The element does have some specialist applications dealing with its radioactivity but otherwise is largely too difficult to produce to have widespread useful significance as a material. Some of its uses are:

neutron startup source for some nuclear reactors, calibrating instrumentation
treatment of certain cervical and brain cancers where other radiation therapy is ineffective
radiography of aircraft to detect metal fatigue
airport neutron-activation detectors of explosives
neutron moisture gauges used to find water and petroleum layers in oil wells
portable neutron source in gold and silver prospecting for on-the-spot analysis
Californium has no biological role and only a few californium compounds have been made and studied. Included among these are: californium oxide (CfO3), californium trichloride (CfCl3) and californium oxychloride (CfOCl). The only californium ion that is stable in aqueous solution is californium (III).

Military use
251Cf is famous for having a very small critical mass, high lethality, and short period of toxic environmental irradiation relative to radioactive elements commonly used for radiation explosive weaponry, creating speculation about possible use in pocket nukes. This urban legend is unfounded since it would be very difficult to make a 251Cf bomb weighing less than 2 kg, and the costs of such a bomb would be prohibitive. Other weaponry uses, such as showering an area with Californium, are not impossible but are seen as inhumane and are subject to inclement weather conditions and porous terrain considerations. Often cited as a consideration is the cost of producing Californium in quantity, but the cost citations are usually due to extra fees that laboratory materials companies insert for sake of caution and market needs. A government need not consider these as prohibitive.

Nuclear fuel cycle
Pertaining to Californium's nuclear fuel cycle, it is important to make sure that the curium concentration in MOX Nuclear fuel is kept low, as neutron irradation of curium will convert some of it to californium. The californium will then cause the used fuel to be more difficult to handle as the californium is a strong neutron emitter (through spontaneous fission). Hence the concentration of curium and californium among the Minor actinides are important.

History
Californium was first synthesized by University of California, Berkeley researchers Stanley Thompson, Kenneth Street, Jr., Albert Ghiorso and Glenn T. Seaborg in 1950. It was the sixth transuranium element to be discovered and the team announced their discovery on March 17, 1950. It was named after the U.S. state of California and for the University of California system.

To produce element 98, the team bombarded a microgram-sized target of 242Cm with 35 MeV alpha particles in the 60-inch Berkeley cyclotron which produced atoms of 245Cf (half-life 44 minutes) and a free neutron.

Isotopes
Nineteen radioisotopes of californium have been characterized, the most stable being 251Cf with a half-life of 898 years, 249Cf with a half-life of 351 years, and 250Cf with a half-life of 13 years. All of the remaining radioactive isotopes have half-lives that are less than 2.7 years, and the majority of these have half-lives shorter than 20 minutes. The isotopes of californium range in atomic weight from 237.062 amu (237Cf) to 256.093 amu (256Cf).

元素名称：锎

元素原子量：[251]

元素类型：金属

发现人：汤普森（S.G.Thompson）、小斯特里特（K.Street Jr.）、乔索（A.Chiorso）和西博格（G 发现年代：1950年

发现过程：

1950年，美国的汤普森（S.G.Thompson）、小斯特里特（K.Street Jr.）、乔索（A.Chiorso）和西博格（G.T.Seaporg）发现。用回旋加速器加速的氦离子轰击242Cm，几乎和锫同时发现。

元素描述：

熔点900℃。金属锎十分容易挥发，在1100~1200℃范围中能蒸馏出来。化学性质活泼，与其他+3价锕系元素相似。有水溶性的硝酸盐、硫酸盐、氯化物和过氯酸盐；它的氟化物、草酸盐、氢氧化物在水溶液中沉淀。利用耙子同位素和轰击粒子的种种组合，已发现了几种锎的同位素：246Cf、249Cf、251Cf、252Cf、254Cf等。251Cf半衰期为900年；249Cf半衰期为360年；252Cf半衰期为2.64年；254Cf半衰期为64天。

元素来源：

锎在地壳中并不存在，因为它的核不稳定。直到1975年，全世界才大约有1克的锎。

元素用途：

可用作高通量的中子源。

元素辅助资料：

接着在锫合成后第二年，也就是1950年，西博格等人用高能量α粒子轰击锔-242获得了98号元素，命名为californium，元素符号定为Cf，以纪念这一元素的发现地——美国的加利福尼亚州（Califorinia）。

西博格和麦克米伦因在合成镎、镅、锔、锫、锎等元素中作出贡献而共同获1951年诺贝尔化学奖，成为发现化学元素而获诺贝尔化学奖的第四和第五人。

锎是世界上最昂贵的金属，是锕系元素，人工合成，利用其衰变释放的中子射流可以有效杀灭癌细胞
它最早是在1950年合成的。

锎的拼音名称是以美国的加利福尼亚州命名。该地是加利福尼亚大学柏克莱分校的所在州份。

由氦同位素轰击锔可得到微量的锎。锎的同位素有244Cf到254Cf。锎-251是最稳定的同位素，它的半衰期有898年。

锎是一种人工合成的放射性化学元素，它的化学符号是Cf，它的原子序数是98，属于锕系元素之一。

它最早是在1950年合成的。

锎的拼音名称是以美国的加利福尼亚州命名。该地是加利福尼亚大学柏克莱分校的所在州份。

由氦同位素轰击锔可得到微量的锎。锎的同位素有244Cf到254Cf。锎-251是最稳定的同位素，它的半衰期有898年。

锎是世界上最昂贵的金属，是锕系元素，人工合成，利用其衰变释放的中子射流可以有效杀灭癌细胞

1g1亿,用于高科技事业,如航空