Uranium

铀

Symbol

符号

Atomic number

原子序数

Atomic mass

原子质量

238.029

Thermal conductivity

热导率

0.276

Atomic radius

原子半径

...

Covalent radius

共价半径

1.42

Density

密度

18.7

Atomic volume

原子体积

12.59

Melting point

熔点

1405

Oxidation states

氧化态

6,5,4,3

Boiling point

沸点

4091

Stable isotopes

稳定同位素

Heat of vapor.

汽化热

477.0

Electronegativity

电负性

1.38

Heat of fusion

熔化热

8.52

First ionization

第一电离能

6.05

Specific heat

比热容

0.12

Electrical conduct.

电导率

...

Electron configuration

电子排布

Uranium

铀

Uranium is the rarest metal of the chromium group. It was not valued until the discovery in 1942 that it was capable of nuclear fission, yielding an enormous amount of energy. For energy use, uranium is usually purified in the form of uranium oxide U₃O₈, commonly called yellowcake. This image of uranium oxide is from Wikipedia.

铀是铬族中最稀有的金属。直到1942年发现它能够发生核裂变，释放出巨大的能量，它才被重视。用于能源用途时，铀通常以氧化铀（U₃O₈）的形式进行提纯，这种物质通常称为黄饼。这张铀氧化物的图片来自维基百科。

Another oxide of uranium is UO₂, found in the mineral uraninite. Uranium is usually found in the ores pitchblende (U₃O₈) and carnotite (K₂U₂V₂O₁₂.3H2O). It is also found in the minerals Becquerelite, euxenite and Boltwoodite. Uranium appears in the phosphate minerals meta-autunite , metatorbernite and sabugalite. Uranium appears with lead in curite and kasolite, both of which exhibit orange coloration which might be the source of color in radioactive orange fiestaware dishes. It appears with vanadium and lead in Francevillite. It appears with cerium and yttrium in samarskite.

另一种铀的氧化物是UO₂，存在于矿物铀矿石（uraninite）中。铀通常存在于矿石pitchblende（U₃O₈）和carnotite（K₂U₂V₂O₁₂·3H₂O）中。它也存在于矿物Becquerelite、euxenite和Boltwoodite中。铀出现在磷酸盐矿物meta-autunite、metatorbernite和sabugalite中。铀与铅共存于curite和kasolite中，这两种矿物都呈现橙色，可能是放射性橙色餐盘染色的来源。它还与vanadium和lead共存于Francevillite中。它还与cerium和yttrium共存于samarskite中。

Uranium Nuclear Data

铀核数据

Z	A	Atomic Mass (u) 原子质量（u）	Nuclear Mass(GeV/c2 核质量（GeV/c²）	Binding Energy(MeV) 结合能（MeV）	Spin 自旋	Natural Abund. 天然丰度	Half-life 半衰期	Decay 衰变	Q MeV Q值（MeV）
92	226	226.029170	210.4995	1725.0	0	...	0.5s	a	7.56
92	231	231.036270	215.1636	1758.7	5/2	...	4.2d	EC 电子俘获（EC）	0.36
92	232	232.037130	216.0959	1766.0	0	...	68.9d	a	5.41
92	233	233.039628	217.0298	1771.8	5/2	...	0.159My 0.159My（专名或术语）	a	4.91
92	234	234.040947	217.9625	1778.6	0	5.5x10^-5	0.245My 0.245My（专名或术语）	a	4.86
92	235	235.043924	218.8968	1783.9	7/2	0.0072	0.704Gy 0.704戈瑞	a	4.68
92	236	236.045563	219.8298	1790.4	0	...	23.4My 23.4My（专名或术语）	a	4.57
92	238	238.050785	221.6977	1801.7	0	0.99275	4.46Gy 4.46Gy（专名或术语）	a	4.27
92	239	239.054290	222.6324	1806.5	5/2	...	23.54m	b-	1.26

Uranium plays a major role in the natural radioactive series on the earth. ²³⁵U is the progenitor of the uranium-235 series, ²³⁸U the progenitor of the uranium-238 series, and ²³³U is a member of the neptunium-237 series. Uranium-235 is the most important isotope for nuclear fission.

铀在地球上的天然放射系中起着重要作用。235U是铀-235系的起源元素，238U是铀-238系的起源元素，而233U是镎-237系的成员。铀-235是核裂变最重要的同位素。

From Evans: "²³⁸U does show a half-period of about 10¹⁶ years for spontaneous fission, or about 25 fissions per hour in 1 gram of ²³⁸U. The probability of a decay is about 10⁷ times as great." The half-life for spontaneous fission for ²³⁵U is about 1.8 x 10¹⁷ years compared to its a half-life of 7 x 10⁸ years.

从Evans处得知：238铀的自发裂变半衰期约为10¹⁶年，即1克238铀每小时约发生25次裂变。衰变的概率大约是10⁷倍。235铀的自发裂变半衰期约为1.8×10¹⁷年，相比之下，其α衰变的半衰期为7×10⁸年。

Uranium is a key to the uranium-lead dating processes in geology, where the ratio found in rock from the Earth, moon and meteorites is ²³⁸U/²³⁵U =137.88 (Dalrymple, Ch. 3). This ratio is use for developing the equations for Pb-Pb isochrons.

铀是地质学中铀-铅定年法的关键，其中在地球、月球和陨石中的岩石中测得的238U/235U比值为137.88（Dalrymple，第3章）。这个比值用于建立Pb-Pb等时线方程。