Se-74, selenium 74 (Russia origin)

الوصف

Selenium is a chemical element with symbol Se and atomic number *4. It is a nonmetal with properties that are intermediate between those of its periodic table column-adjacent chalcogen elements sulfur and tellurium. It rarely occurs in its elemental state in nature, or as pure ore compounds.
Selenium (Se) has six naturally occurring isotopes, five of which are stable:*4Se,*6Se,*7Se,*8Se, and*0Se. The last three also occur as fission products, along with*9Se which has a half-life of **7,**0 years and*2Se which has a very long half-life (~***0 years, decaying via double beta decay to*2Kr) and for practical purposes can be considered to be stable. *3 other unstable isotopes have been characterized. Standard atomic mass: *8.*6(3) u