34
Se
16
週期
4
p
個質子
電子
個中子
34
34
45
一般屬性
原子序數
34
標準原子質量
78.96
品質編號
79
類別
非金屬
顏色
灰色
放射性
From the Greek word Selene, moon
晶體結構
以基中心單核
歷史
Selenium was first observed in about the year 1300 by the alchemist Arnold of Villanova.

Selenium was discovered in 1817 by Jöns Jacob Berzelius and Johan Gottlieb Gahn who noted the similarity of the new element to the previously-known tellurium.

In 1873, Willoughby Smith found that the electrical resistance of grey selenium was dependent on the ambient light.
每個外殼的電子
2, 8, 18, 6
電子排布
[Ar] 3d10 4s2 4p4
Se
Selenium deficiency in animals can lead to slow growth
物理性質
物態
固體
密度
4.809 g/cm3
熔點
494.15 K | 221 °C | 429.8 °F
沸點
958.15 K | 685 °C | 1265 °F
熔化熱
5.4 kJ/mol
汽化熱
26 kJ/mol
比熱容
0.321 J/g·K
地殼豐度
5×10-6%
宇宙豐度
3×10-6%
Ultrapure
圖片來源: Images-of-elements
Ultrapure black, amorphous selenium
CAS 編號
7782-49-2
Pubchem CID 編號
6326970
原子性質
原子半徑
120 pm
共價半徑
120 pm
電負性
2.55 (鲍林标度)
電離電位
9.7524 eV
原子體積
16.45 cm3/mol
熱導率
0.0204 W/cm·K
氧化態
-2, 2, 4, 6
應用
Selenium is used in the glass industry to decolorize glass and to make red-colored glasses and enamels.

It is used as a catalyst in many chemical reactions.

It is also used as a photographic toner, and as an additive to stainless steel.

Selenium sulfide is used in anti-dandruff shampoos.
Many of selenium's compounds, such as selenates and selenites, are highly toxic
同位素
穩定同位素
74Se, 76Se, 77Se, 78Se, 80Se
不穩定同位素
65Se, 66Se, 67Se, 68Se, 69Se, 70Se, 71Se, 72Se, 73Se, 75Se, 79Se, 81Se, 82Se, 83Se, 84Se, 85Se, 86Se, 87Se, 88Se, 89Se, 90Se, 91Se, 92Se, 93Se, 94Se