Selenium 34

Atomic No. Order:

Alphabetic Order:

Periodic Table

2, 8, 18,

O
8

S
16

Se
34

Te
52

Po
84

Uuh
116

Uhh
166

Buh
216

Selenium

Symbol

Atomic Number

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 cm³

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

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

Inner + outer Orbitals

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

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

0, 0, 0, 24

Singularity

	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

³P₂

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).

APSIDIUM ©	Created:		2002-06-01		034.pdf
	Page update:		2004-06-20		034.pdf