Selenium

Properties
Atomic symbol |  Se
Atomic number |  34
Classification |  Non-metal
Atomic mass |  79.0 amu
Other Information
Date of discovery |  1817
Name of discoverer |  Jöns Berzelius
Name origin |  From the Greek word Selênê (Moon)
Uses |  Photoelectric cells, TV cameras
Obtained from |  Refining of lead, copper, nickel

Periodic Table of the Elements

1  | 2  | 3  | 4  | 5  | 6  | 7  | 8  | 9  | 10  | 11  | 12  | 13  | 14  | 15  | 16  | 17  | 18

1.008

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

4.003

6.939

9.0122

|  |  |  |  |  |  |  |  |  |  |

10.811

12.011

14.007

15.999

18.998

10.183

22.99

24.312

|  |  |  |  |  |  |  |  |  |  |

26.982

28.086

30.974

32.064

35.453

39.948

39.102

40.08

44.956

47.9

50.942

51.996

54.938

55.847

58.933

58.71

63.546

65.37

69.72

72.59

74.922

78.96

79.904

83.8

85.47

87.62

88.905

91.22

92.906

95.94

[97]

101.07

102.91

106.4

107.87

112.4

114.82

118.69

121.75

127.6

126.9

131.3

132.91

137.34

57*

138.91

178.49

180.95

183.85

186.2

190.2

192.2

195.09

196.97

200.59

204.37

207.19

208.98

210

210

222

215

226.03

89**

227.03

104

[261]

105

[262]

106

[266]

107

[264]

108

[265]

109

[268]

110

[271]

111

[272]

112

[277]

113

[284]

114

[289]

115

[288]

116

[292]

117

[293]

118

[294]

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
*Lanthanides  |

140.12

140.91

144.24

145

150.35

151.96

157.25

158.92

162.5

164.93

167.26

168.93

173.04

174.97

|  |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
**Actinides  |

232.04

231

238.03

237.05

239.05

241.06

244.06

249.08

252.08

252.08

100

257.1

101

258.1

102

259.1

103

262.11

|  |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Selenium (si-LEE-nee-em) is a conductive non-metal. It is primarily useful in electronic devices, especially in light-sensitive devices.

## Contents

* 1 History
* 2 Additional Properties
* 3 Uses
* 4 References
* 5 External links

## History[edit]

Selenium was discovered by a Swedish chemist named Jöns Jacob Berzelius, in 1817.[1]

## Additional Properties[edit]

Melting Point: 428.9 °F (220.5 °C or 493.65 K)

Boiling Point: 1265 °F (685 °C or 958 K)

Density: 4.809 grams per cubic centimeter

State of Matter at Room Temperature: Solid[2]

Color: gray[3]

## Uses[edit]

Selenium's electrical resistance is greatly affected by the amount of light shining on it. Bright light causes it to conduct better, while darkness reduces conductivity. This special property has made selenium useful in devices that respond to the intensity of light, such as electric eyes, photo cells, light meters for cameras and copiers. It is also is able to generate energy in direct sunlight. For this reason, it is a vital ingredient of solar cells.[4] Selenium is also useful in converting alternating current to direct current, which is why it is used in rectifiers.

## References[edit]

1. ↑ http://education.jlab.org/itselemental/ele034.html
2. ↑ http://education.jlab.org/itselemental/ele034.html
3. ↑ http://www.chemicalelements.com/elements/se.html
4. ↑ http://education.jlab.org/itselemental/ele034.html

## External links[edit]

* https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional
* http://www.chemicalelements.com/elements/se.html