Селен

34
Se
Група
16
Периода
4
блок
p
Protons
Electrons
Neutrons
34
34
45
Општи Својства
Атомски број
34
Атомска тежина
78,96
Mass Number
79
Category
Неметали
Color
Gray
Radioactive
Не
From the Greek word Selene, moon
Кристална структура
Simple Monoclinic
History
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.
Electrons per shell
2, 8, 18, 6
Електронска конфигурација
[Ar] 3d10 4s2 4p4
Se
Selenium deficiency in animals can lead to slow growth
Физички Својства
Фаза
Solid
Густина
4,809 g/cm3
Точка на топење
494,15 K | 221 °C | 429,8 °F
Точка на вриење
958,15 K | 685 °C | 1265 °F
Топлина на топење
5,4 kJ/mol
Топлина на испарување
26 kJ/mol
Specific Heat Capacity
0,321 J/g·K
Abundance in Earth's crust
5×10-6%
Abundance in Universe
3×10-6%
Ultrapure
Кредити на слика: Images-of-elements
Ultrapure black, amorphous selenium
CAS Number
7782-49-2
PubChem CID Number
6326970
Атомски Својства
Атомски полупречник
120 pm
Ковалентен полупречник
120 pm
Електронегативност
2,55 (Полингова скала)
Ionization Potential
9,7524 eV
Atomic Volume
16,45 cm3/mol
Thermal Conductivity
0,0204 W/cm·K
Oxidation States
-2, 2, 4, 6
Applications
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
Isotopes
Stable Isotopes
74Se, 76Se, 77Se, 78Se, 80Se
Unstable Isotopes
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