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 Atomic No. Order:
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 Alphabetic Order:
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 Periodic Table

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  2, 8, 18,  

  6  

 

 

  O
 8 		  S
16 		  Se 
34 		Te
52 		Po
84 		  Uuh
116 		Uhh
166 		Buh
216

Selenium

Symbol Se
Atomic Number 34
Relative Atomic Mass
12C = 12.0000 		78.96  (±3) [Since 1999]
Atomic Radius pm 117
First Ionisation Energy
kJ mol -1 		940.9
Ionisation Energy  (eV) 9.7524
Electronegativity 2.55
Density
kg m -3 		4790 (grey) [293 K]
3987 [l., m.p.]
Molar Volume   cm 3 16.48
Thermal Conductivity
W m -1 K -1 		2.04 [300 K]
Melting Point   K 490
Boiling Point   K 958.1
Number of Isotopes 26
Isotope Atomic mass/u Mole fraction 74Se 73.922 4767(16) 0.0089(4)
76Se 75.919 2143(16) 0.0937(29)
77Se 76.919 9148(16) 0.0763(16)
78Se 77.917 3097(16) 0.2377(28)
80Se 79.916 5221(20) 0.4961(41)
82Se 81.916 7003(22) 0.0873(22)
 
Inner + outer Shells
  3   +   1    = 4
Inner + outer Orbitals
  28   +   6    = 34
Filling Orbital
  4p 4   
Ground State Electron
Configuration
[Ar]  3d 10    4s 2    4p 4   
Ground State Electron
Configuration with
free Orbitals (n=2)

 

  0, 0, 0, 2  

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Ground State Electron
Configuration with
compressed Orbitals (n=24)

 

  0, 0, 0, 24  

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Singularity
60 =  28 + 6 + 2 + 24
 
 
s
p
d
 f
g
h
i
j
1
2
             
2
2
6
           
3
2
6
10
         
4
2
4
2 10

14

       
5
               
6
               
7
               
  
Term Symbol 3P 2
Discovery It was discovered by the Swedish chemist Jöns Jacob Berzelius (Stockholm, Sweden) in 1817, while trying to isolate tellurium in an impure sample.
 
Name Derived From The name derives from the Greek Selene, who was the Greek goddess of the Moon because the element is chemically found with tellurium (Tellus-the Roman goddess of the earth).
 

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