卵裂8c是什么意思？核言碎语143

卵裂8c是什么意思？核言碎语143Uranium is a naturally-occurring chemical element with atomic number 92 which means there are 92 protons and 92 electrons in the atomic structure. The chemical symbol for uranium is U. Uranium is commonly found at low levels (a few ppm – parts per million) in all rocks soil water plants and animals (including humans). Uranium occurs also in seawater and can be recovered from the ocean water.

111 核素

Nuclides

（https://www.nuclear-power.com/）

核素

Examples of Nuclides

核素示例

Uranium

铀

Uranium is a naturally-occurring chemical element with atomic number 92 which means there are 92 protons and 92 electrons in the atomic structure. The chemical symbol for uranium is U. Uranium is commonly found at low levels (a few ppm – parts per million) in all rocks soil water plants and animals (including humans). Uranium occurs also in seawater and can be recovered from the ocean water. Significant concentrations of uranium occur in some substances such as uraninite (the most common uranium ore) phosphate rock deposits and other minerals.

铀是一种天然存在的化学元素，原子序数为92，这意味着原子结构中有92个质子和92个电子。铀的化学符号是U。铀通常在所有的岩石、土壤、水、植物和动物（包括人类）中含量很低（几ppm-百万分之几）。铀也存在于海水中，并可以从海水中回收。铀在某些物质，如沥青铀矿（最常见的铀矿石）、磷矿床和其他矿物中浓度很高。

Natural uranium consists primarily of isotope 238U (99.28%) therefore the atomic mass of uranium element is close to the atomic mass of 238U isotope (238.03u). Natural uranium also consists of two other isotopes: 235U (0.71%) and 234U (0.0054%). The abundance of isotopes in the nature is caused by difference in the half-lifes. All three naturally-occurring isotopes of uranium (238U 235U and 234U) are unstable. On the other hand these isotopes (except 234U) belong to primordial nuclides because their half-life is comparable to the age of the Earth (~4.5×109 years for 238U).

天然铀主要由238U（99.28%）同位素组成，因此铀元素的原子质量接近238U同位素（238.03u）的原子质量。天然铀还含有另外两种同位素: 235U（0.71%）和234U（0.0054%）。自然界中同位素的丰度是由其半衰期的差异造成的。铀的三种天然同位素（238U、235U和234U）都不稳定。另一方面，这些同位素（234U除外）属于原始核素，因为它们的半衰期与地球的年龄相当（238U为~4.5×10^9年）。

In nuclear reactors we have to consider three artificial isotopes 236U 233U and 232U. These are produced by transmutation in nuclear reactors from 235U and 232Th.

在核反应堆中，我们必须考虑三种人工同位素，236U 233U和232U。它们是由235U和232Th的核反应堆的嬗变产生的。

（待续）