As - Arsenic

33
As
Arsenic

Arsenic Element Information, Facts, Properties, Trends, Uses, Comparison with other elements

Element 33 of Periodic table is Arsenic with atomic number 33, atomic weight 74.9216. Arsenic, symbol As, has a Simple Trigonal structure and Silver color. Arsenic is a Metalloid element. It is part of group 15 (nitrogen family). Know everything about Arsenic Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.
33 As - Arsenic | SchoolMyKids

Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. Arsenic is a Metalloid.

It belongs to group 15 of the periodic table having trivial name pentels, pnictogens*. You can also download Printable Periodic Table of Elements Flashcards for Arsenic in a PDF format.

Arsenic Facts

Read key information and facts about element Arsenic

NameArsenic
Atomic Number33
Atomic SymbolAs
Atomic Weight74.9216
PhaseSolid
ColorSilver
Appearancemetallic grey
ClassificationMetalloid
Natural OccurancePrimordial
Group in Periodic Table15
Group Namenitrogen family
Period in Periodic Tableperiod 4
Block in Periodic Tablep-block
Electronic Configuration[Ar] 3d10 4s2 4p3
Electronic Shell Structure (Electrons per shell)2, 8, 18, 5
Melting Point1090 K
Boiling Point887 K
CAS NumberCAS7440-38-2
123456789101112131415161718
1
1
H
Hydrogen
1.008

Atomic #

Electronic Shell #

Symbol
Name
Atomic Weight
HGas
HgLiquid
CSolid
Metals
Metalloids
NonMetals
Alkali metals
Alkali earth metals
Lanthanoids
Transition metals
Post-transition metals
Other nonmetals
Halogens
Nobel gas
Actinoids
2
He
Helium
4.003
2
3
Li
Lithium
6.941
4
Be
Beryllium
9.012
5
B
Boron
10.811
6
C
Carbon
12.011
7
N
Nitrogen
14.007
8
O
Oxygen
15.999
9
F
Fluorine
18.998
10
Ne
Neon
20.180
3
11
Na
Sodium
22.990
12
Mg
Magnesium
24.305
13
Al
Aluminium
26.982
14
Si
Silicon
28.085
15
P
Phosphorus
30.974
16
S
Sulfur
32.065
17
Cl
Chlorine
35.453
18
Ar
Argon
39.948
4
19
K
Potassium
39.098
20
Ca
Calcium
40.078
21
Sc
Scandium
44.956
22
Ti
Titanium
47.867
23
V
Vanadium
50.941
24
Cr
Chromium
51.996
25
Mn
Manganese
54.938
26
Fe
Iron
55.845
27
Co
Cobalt
58.933
28
Ni
Nickel
58.693
29
Cu
Copper
63.546
30
Zn
Zinc
65.409
31
Ga
Gallium
69.723
32
Ge
Germanium
72.640
33
As
Arsenic
74.922
34
Se
Selenium
78.960
35
Br
Bromine
79.904
36
Kr
Krypton
83.798
5
37
Rb
Rubidium
85.468
38
Sr
Strontium
87.620
39
Y
Yttrium
88.906
40
Zr
Zirconium
91.224
41
Nb
Niobium
92.906
42
Mo
Molybdenum
95.940
43
Tc
Technetium
98
44
Ru
Ruthenium
101.070
45
Rh
Rhodium
102.906
46
Pd
Palladium
106.420
47
Ag
Silver
107.868
48
Cd
Cadmium
112.411
49
In
Indium
114.818
50
Sn
Tin
118.710
51
Sb
Antimony
121.760
52
Te
Tellurium
127.600
53
I
Iodine
126.904
54
Xe
Xenon
131.293
6
55
Cs
Cesium
132.905
56
Ba
Barium
137.327
57 - 71
La - Lu
Lanthanides
72
Hf
Hafnium
178.490
73
Ta
Tantalum
180.948
74
W
Tungsten
183.840
75
Re
Rhenium
186.207
76
Os
Osmium
190.230
77
Ir
Iridium
192.217
78
Pt
Platinum
195.078
79
Au
Gold
196.967
80
Hg
Mercury
200.590
81
Tl
Thallium
204.383
82
Pb
Lead
207.200
83
Bi
Bismuth
208.980
84
Po
Polonium
209
85
At
Astatine
210
86
Rn
Radon
222
7
87
Fr
Francium
223
88
Ra
Radium
226
89 - 103
Ac - Lr
Actinides
104
Rf
Rutherfordium
261
105
Db
Dubnium
262
106
Sg
Seaborgium
266
107
Bh
Bohrium
264
108
Hs
Hassium
269
109
Mt
Meitnerium
268
110
Ds
Darmstadtium
281
111
Rg
Roentgenium
272
112
Cn
Copernicium
285
113
Nh
Nihonium
284
114
Fl
Flerovium
289
115
Mc
Moscovium
288
116
Lv
Livermorium
292
117
Ts
Tennessine
294
118
Og
Oganesson
294
Lanthanides
57
La
Lanthanum
138.905
58
Ce
Cerium
140.116
59
Pr
Praseodymium
140.908
60
Nd
Neodymium
144.240
61
Pm
Promethium
145
62
Sm
Samarium
150.360
63
Eu
Europium
151.964
64
Gd
Gadolinium
157.250
65
Tb
Terbium
158.925
66
Dy
Dysprosium
162.500
67
Ho
Holmium
164.930
68
Er
Erbium
167.259
69
Tm
Thulium
168.934
70
Yb
Ytterbium
173.040
71
Lu
Lutetium
174.967
Actinides
89
Ac
Actinium
227
90
Th
Thorium
232.038
91
Pa
Protactinium
231.036
92
U
Uranium
238.029
93
Np
Neptunium
237
94
Pu
Plutonium
244
95
Am
Americium
243
96
Cm
Curium
247
97
Bk
Berkelium
247
98
Cf
Californium
251
99
Es
Einsteinium
252
100
Fm
Fermium
257
101
Md
Mendelevium
258
102
No
Nobelium
259
103
Lr
Lawrencium
262

How to Locate Arsenic on Periodic Table

Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 33 to find Arsenic on periodic table.

Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Arsenic on periodic table look for cross section of group 15 and period 4 in the modern periodic table.

Arsenic History

The element Arsenic was discovered by Arabic alchemist in year ca. 800 AD . Arsenic was first isolated by in . Arsenic derived its name English word (Latin arsenicum).

Discovered By Arabic alchemist
Discovery Date ca. 800 AD
First Isolation
Isolated by

First isolated by Jabir ibn Hayyan , an Arabian alchemist. Albertus Magnus was the first European to isolate the element.

Arsenic Uses

This element is used as a doping agent in transistors, majorly with Gallium. Many arsenic compounds are used as insecticides and poisons.

Arsenic Presence: Abundance in Nature and Around Us

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

 ppb by weight (1ppb =10^-7 %)ppb by atoms (1ppb =10^-7 %)
Abundance in Universe80.1
Abundance in Sun--
Abundance in Meteorites1800460
Abundance in Earth's Crust2100580
Abundance in Oceans2.30.19
Abundance in Humans504

Crystal Structure of Arsenic

The solid state structure of Arsenic is Simple Trigonal.

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)

abc
375.98 pm375.98 pm1054.75 pm

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

alphabetagamma
π/2 π/2 2 π/3

The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) 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.

Space Group NameR_ 3m
Space Group Number166
Crystal StructureSimple Trigonal
Number of atoms per unit cell
33 As Arsenic - Crystal Structure | SchoolMyKids

The number of atoms per unit cell in a simple cubic, face-centered cubic and body-centred cubic are 1,4,2 respectively.

Arsenic Atomic and Orbital Properties

Arsenic atoms have 33 electrons and the electronic shell structure is [2, 8, 18, 5] with Atomic Term Symbol (Quantum Numbers) 4S3/2.

Atomic Number33
Number of Electrons (with no charge)33
Number of Protons33
Mass Number75
Number of Neutrons42
Shell structure (Electrons per energy level)2, 8, 18, 5
Electron Configuration[Ar] 3d10 4s2 4p3
Valence Electrons4s2 4p3
Valence (Valency)5
Main Oxidation States-3, 3, 5
Oxidation States-3, -2, -1, 0, 1, 2, 3, 4, 5
Atomic Term Symbol (Quantum Numbers)4S3/2

Bohr Atomic Model of Arsenic - Electrons per energy level

33 As Arsenic Electron Shell Structure | SchoolMyKids
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Ground State Electronic Configuration of Arsenic - neutral Arsenic atom

Abbreviated electronic configuration of Arsenic

The ground state abbreviated electronic configuration of Neutral Arsenic atom is [Ar] 3d10 4s2 4p3. The portion of Arsenic 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 4s2 4p3, electrons in the outermost shell that determine the chemical properties of the element.

Unabbreviated electronic configuration of neutral Arsenic

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

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p3

Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.

As per the Aufbau principle the electrons will occupy the orbitals having lower energies before occupying higher energy orbitals. According to this principle, electrons are filled in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…

The Pauli exclusion principle states that a maximum of two electrons, each having opposite spins, can fit in an orbital.

Hund's rule states that every orbital in a given subshell is singly occupied by electrons before a second electron is filled in an orbital.

Electron configuration of Arsenic

Atomic Structure of Arsenic

Arsenic atomic radius is 114 pm, while it's covalent radius is 119 pm.

Atomic Radius Calculated114 pm(1.14 Å)
Atomic Radius Empirical115 pm (1.15 Å)
Atomic Volume12.95 cm3/mol
Covalent Radius119 pm (1.19 Å)
Van der Waals Radius185 pm
Neutron Cross Section4.3
Neutron Mass Absorption 0.002

Spectral Lines of Arsenic - Atomic Spectrum of Arsenic

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules.

Spectral lines are the result of interaction between a quantum system and a single photon. A spectral line may be observed either as an emission line or an absorption line.

Spectral lines are highly atom-specific, and can be used to identify the chemical composition of any medium. Several elements, including helium, thallium, and caesium, were discovered by spectroscopic means. They are widely used to determine the physical conditions of stars and other celestial bodies that cannot be analyzed by other means.

Emission spectrum of Arsenic

Emission Spectrum of Arsenic | SchoolMyKids

Absorption spectrum of Arsenic

Absorption Spectrum of Arsenic | SchoolMyKids

Arsenic Chemical Properties: Arsenic Ionization Energies and electron affinity

The electron affinity of Arsenic is 78 kJ/mol.

Valence5
Electronegativity2.18
ElectronAffinity78 kJ/mol

Ionization Energy of Arsenic

Ionization energy is the amount of energy required to remove an electron from an atom or molecule.in chemistry, this energy is expresed in kilocalories per mole (kcal/mol) or kilojoules per mole (kJ/mol).

Refer to table below for Ionization energies of Arsenic

Ionization energy numberEnthalpy - kJ/mol
1st947
2nd1798
3rd2735
4th4837
5th6043
6th12310

Arsenic Physical Properties

Refer to below table for Arsenic Physical Properties

Density5.727 g/cm3(when liquid at m.p density is $5.22 g/cm3)
Molar Volume12.95 cm3/mol

Elastic Properties

Young Modulus8
Shear Modulus-
Bulk Modulus 22 GPa
Poisson Ratio-

Hardness of Arsenic - Tests to Measure of Hardness of Element

Mohs Hardness3.5 MPa
Vickers Hardness-
Brinell Hardness1440 MPa

Arsenic Electrical Properties

Electrical resistivity measures element's electrical resistance or how strongly it resists electric current.The SI unit of electrical resistivity is the ohm-metre (Ω⋅m). While Electrical conductivity is the reciprocal of electrical resistivity. It represents a element's ability to conduct electric current. The SI unit of electrical conductivity is siemens per metre (S/m).

Arsenic is a conductor of electricity. Refer to table below for the Electrical properties of Arsenic

Electrical conductors Conductor
Electrical Conductivity3300000 S/m
Resistivity3e-7 m Ω
Superconducting Point-

Arsenic Heat and Conduction Properties

Thermal Conductivity50 W/(m K)
Thermal Expansion-

Arsenic Magnetic Properties

Magnetic TypeDiamagnetic
Curie Point-
Mass Magnetic Susceptibility-3.9e-9 m3/kg
Molar Magnetic Susceptibility-2.92e-10 m3/mol
Volume Magnetic Susceptibility-0.0000223

Optical Properties of Arsenic

Refractive Index1.001552

Acoustic Properties of Arsenic

Speed of Sound-

Arsenic Thermal Properties - Enthalpies and thermodynamics

Refer to table below for Thermal properties of Arsenic

Melting Point1090 K(816.85 °C, 1502.330 °F)
Boiling Point887 K(613.85 °C, 1136.930 °F)
Critical Temperature-
Superconducting Point-

Enthalpies of Arsenic

Heat of Fusion27.7 kJ/mol
Heat of Vaporization32.4 kJ/mol
Heat of Combustion-

Arsenic Isotopes - Nuclear Properties of Arsenic

Arsenic has 33 isotopes, with between 60 and 92 nucleons. Arsenic has 1 stable naturally occuring isotopes.

Isotopes of Arsenic - Naturally occurring stable Isotopes: 75As.

IsotopeZNIsotope Mass% AbundanceT halfDecay Mode
60As332760Synthetic
61As332861Synthetic
62As332962Synthetic
63As333063Synthetic
64As333164Synthetic
65As333265Synthetic
66As333366Synthetic
67As333467Synthetic
68As333568Synthetic
69As333669Synthetic
70As333770Synthetic
71As333871Synthetic
72As333972Synthetic
73As334073Synthetic
74As334174Synthetic
75As334275100%Stable
76As334376Synthetic
77As334477Synthetic
78As334578Synthetic
79As334679Synthetic
80As334780Synthetic
81As334881Synthetic
82As334982Synthetic
83As335083Synthetic
84As335184Synthetic
85As335285Synthetic
86As335386Synthetic
87As335487Synthetic
88As335588Synthetic
89As335689Synthetic
90As335790Synthetic
91As335891Synthetic
92As335992Synthetic

Regulatory and Health - Health and Safety Parameters and Guidelines

The United States Department of Transportation (DOT) identifies hazard class of all dangerous elements/goods/commodities either by its class (or division) number or name. The DOT has divided these materials into nine different categories, known as Hazard Classes.

Toxic substances

NFPA 704 is a Standard System for the Identification of the Hazards of Materials for Emergency Response. NFPA is a standard maintained by the US based National Fire Protection Association.

The health (blue), flammability (red), and reactivity (yellow) rating all use a numbering scale ranging from 0 to 4. A value of zero means that the element poses no hazard; a rating of four indicates extreme danger.

NFPA Fire Rating2Flash Points Above 37.8°C (100°F) not exceeding 93.3°C (200°F)
NFPA Health Rating3 Flash Points below 37.8°C (100°F)
NFPA Reactivity Rating
NFPA Hazards
Autoignition Point-
Flashpoint-

Database Search

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

DatabaseIdentifier number
CAS Number - Chemical Abstracts Service (CAS)CAS7440-38-2
RTECS Number{N/A, RTECSCG0525000, N/A}
CID Number {CID5359596, CID5359596, CID139279}
Gmelin Number-
NSC Number-

Frequently Asked Questions (FAQ)

Find the answers to the most frequently asked questions about Arsenic

The electronic configuration of Arsenic is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p3.

The abbreviated electronic configuration of Arsenic is [Ar] 3d10 4s2 4p3. To form abbreviated notation of electronic configuration, the completely filled subshells are replaced by the noble gas of the preceding period in square brackets.

Symbol of Arsenic is As. Arsenic is a chemical element with symbol As and atomic number 33.

Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic is the 33 element on the periodic table. It is located in group 15 and period 4 in the modern periodic table.

The atomic number of Arsenic is 33.

Arsenic is of Silver color.

The element Arsenic was discovered by Arabic alchemist in year ca. 800 AD . Arsenic was first isolated by in .

Arsenic has 5 valence electrons. Arsenic has 33 electrons out of which 5 valence electrons are present in the 4s2 4p3 outer orbitals of atom.

Melting Point of Arsenic is 1090 K.

Boiling Point of Arsenic is 887 K.

Melting Point of Arsenic in Kelvin is 1090 K.

Boiling Point of Arsenic in Kelvin is 887 K.

Melting Point of Arsenic in Celsius is 816.85 °C.

Boiling Point of Arsenic in Celsius is 613.85 °C.

Melting Point of Arsenic in Fahrenheit is 1502.33 °F.

Boiling Point of Arsenic in Fahrenheit is 1136.93 °F.

The electronic configuration of Arsenic will be 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p3.

The electronic configuration of Arsenic will be 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p3.