Ground State Electron Configuration for the Selenium Atom

Selenium History

The element Selenium was discovered by Jöns Jakob Berzelius in year 1817 in Sweden . Selenium derived its name from the Greek selene, meaning 'moon'

Selenium Presence: Abundance in Nature and Around Us

The table below shows the abundance of Selenium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.

	Ppb by weight (1ppb =10^-7 %)
Abundance in Universe	3×10-6%
Abundance in Sun	N/A
Abundance in Meteorites	1.3e-05
Abundance in Earth's Crust	5×10-6%
Abundance in Oceans	4.5×10-8%
Abundance in Humans	5×10-6%

Crystal Structure of Selenium

The solid state structure of Selenium is Simple Monoclinic.

The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.

Unit Cell Parameters

The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)

a	b	c
905.4	908.3	1160.1 pm

and the angles between them Lattice Angles (alpha, beta and gamma).

alpha	beta	gamma
π/2	1.58493	π/2

The positions of the atoms inside the unit cell are described by the set of atomic positions ( x_i, y_i, z_i) measured from a reference lattice point.

The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.

Selenium Atomic and Orbital Properties

Selenium atoms have 34 electrons and the electronic shell structure is [2, 8, 18, 6] with Atomic Term Symbol (Quantum Numbers) ³P₂.

Shell Structure of Selenium - Electrons per energy level

n		s	p	d	f
1	K	2
2	L	2	6
3	M	2	6	10
4	N	2	4

Ground State Electronic Configuration of Selenium - neutral Selenium atom

The ground state electronic configuration of Neutral Selenium atom is [Ar] 3d10 4s2 4p4. The portion of Selenium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Ar]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used.This is important as it is the Valence electrons 3d10 4s2 4p4, electrons in the outermost shell that determine the chemical properties of the element.

Unabbreviated electronic configuration of neutral Selenium

Complete ground state electronic configuration for the Selenium atom, Unabbreviated electronic configuration

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p4

Atomic Structure of Selenium

Selenium atomic radius is 103 pm, while it's covalent radius is 116 pm.

Atomic Spectrum of Selenium

Selenium Chemical Properties: Selenium Ionization Energies and electron affinity

The electron affinity of Selenium is 195 kJ/mol

Ionization Energy of Selenium

Refer to table below for Ionization energies of Selenium

Ionization energy number	Enthalpy - kJ/mol
1	941
2	2045
3	2973.7
4	4144
5	6590
6	7880
7	14990

Selenium Physical Properties

Refer to below table for Selenium Physical Properties

Density	4.819 g/cm3
Molar Volume	16.3851421457 cm3

Elastic Properties

Hardness of Selenium - Tests to Measure of Hardness of Element

Selenium Electrical Properties

Selenium is N/A of electricity. Refer to table below for the Electrical properties of Selenium

Selenium Heat and Conduction Properties

Selenium Magnetic Properties

Optical Properties of Selenium

Acoustic Properties of Selenium

Selenium Thermal Properties - Enthalpies and thermodynamics

Refer to table below for Thermal properties of Selenium

Enthalpies of Selenium

Selenium Isotopes - Nuclear Properties of Selenium

Isotopes of rhodium. Naturally occurring Selenium has 5 stable isotope - 74Se, 76Se, 77Se, 78Se, 80Se.

Isotope	Isotope Mass	% Abundance	T half	Decay Mode
65Se
66Se
67Se
68Se
69Se
70Se
71Se
72Se
73Se
74Se		0.89%	Stable	N/A
75Se
76Se		9.37%	Stable	N/A
77Se		7.63%	Stable	N/A
78Se		23.77%	Stable	N/A
79Se
80Se		49.61%	Stable	N/A
81Se
82Se		8.73%
83Se
84Se
85Se
86Se
87Se
88Se
89Se
90Se
91Se
92Se
93Se
94Se

Regulatory and Health - Health and Safety Parameters and Guidelines

CAS Number	CAS7782-49-2
RTECS Number	{N/A, RTECSVS7700000, N/A}
DOT Hazard Class	{N/A, 6.1, N/A}
DOT Numbers	"N/A", {2658}, "N/A"
EU Number	{N/A, N/A, N/A}
NFPA Fire Rating	{N/A, 0, N/A}
NFPA Hazards	N/ A, N/ A, N/ A
NFPA Health Rating	{N/A, 2, N/A}
NFPA Reactivity Rating	{N/A, 0, N/A}

Database Search

List of unique identifiers to search the element in various chemical registry databases

Database	Identifier number
CAS Number - Chemical Abstracts Service (CAS)	CAS7782-49-2
CID Number	{CID6326970, CID6326970, CID139346}
Gmelin Number	{N/A, N/A, N/A}
NSC Number	{N/A, N/A, N/A}
RTECS Number	{N/A, RTECSVS7700000, N/A}

Ground State Electron Configuration for the Selenium Atom

Source: https://www.schoolmykids.com/learn/interactive-periodic-table/se-selenium#:~:text=The%20ground%20state%20electronic%20configuration,%5BAr%5D%203d10%204s2%204p4.

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