Thallium

Element 81 of Periodic table is Thallium with atomic number 81, atomic weight 204.3833. Thallium, symbol Tl, has a Simple Hexagonal structure and Silver color. Thallium is a post-transition metal element. Trivial name of Thallium is triels, icosagens. Know everything about Thallium Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.


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Thallium is a chemical element with symbol Tl and atomic number 81. This soft gray post-transition metal is not found free in nature. When isolated, it resembles tin, but discolors when exposed to air.

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Thallium Facts

Read key information and facts about element Thallium

Name Thallium
Atomic Number 81
Atomic Symbol Tl
Atomic Weight 204.3833
Phase Solid
Color Silver
Classification post-transition metal
Group in Periodic Table 13
Group Name boron family
Period in Periodic Table 6
Block in Periodic Table p-block
Electronic Configuration 4f14 5d10 6s2 6p1
Melting Point 304 °C
Boiling Point 1473 °C
Electronic Shell Structure <2, 8, 18, 32, 18, 3>
CAS Number CAS7440-28-0

Neighborhood
48
Cd
49
In
50
Sn
80
Hg
81
Tl
82
Pb
112
Cn
113
Nh
114
Fl
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1
1
H
2
He
2
3
Li
4
Be
5
B
6
C
7
N
8
O
9
F
10
Ne
3
11
Na
12
Mg
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
4
19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
5
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
6
55
Cs
56
Ba
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
7
87
Fr
88
Ra
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
Nh
114
Fl
115
Mc
116
Lv
117
Ts
118
Og
Lanthanides
57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
Actinide
89
Ac
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr

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How to Locate Thallium 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 81 to find Thallium 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 Thallium on periodic table look for cross section of group 13 and period 6 in the modern periodic table.

Explore Interactive Periodic Table to Understand and Learn Cool Trends

Table of Contents


History
Abundance
Physical Properties
Thermal Properties
Crystal Structure
Atomic & Orbital Properties
Chemical Properties
Isotopes
Health and Safety Parameters and Guidelines
Databases
Compare Thallium with other elements

Thallium History

The element Thallium was discovered by William Crookes in year 1861 in United Kingdom . Thallium derived its name from the Greek thallos, "green twig"

Thallium Presence: Abundance in Nature and Around Us

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

Ppb by weight (1ppb =10^-7 %)
Abundance in Universe 5×10-8%
Abundance in Sun 1×10-7%
Abundance in Meteorites 7.8×10-6%
Abundance in Earth"s Crust 5.3e-07
Abundance in Oceans 1×10-10%
Abundance in Humans N/A

Crystal Structure of Thallium

The solid state structure of Thallium is Simple Hexagonal.

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
345.66 345.66 552.48 pm

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

alpha beta gamma
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 Name P63/mmc
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Space Group Number 194
Crystal Structure Simple Hexagonal

Thallium Atomic and Orbital Properties

Thallium atoms have 81 electrons and the electronic shell structure is <2, 8, 18, 32, 18, 3> with Atomic Term Symbol (Quantum Numbers) 2P1/2.


Atomic Number 81
Number of Electrons (with no charge) 81
Number of Protons 81
Mass Number 204
Number of Neutrons 123
Shell structure (Electrons per energy level) <2, 8, 18, 32, 18, 3>
Electron Configuration 4f14 5d10 6s2 6p1
Valence Electrons 6s2 6p1
Oxidation State -5;-2;-1 1;2;3
Atomic Term Symbol (Quantum Numbers) 2P1/2

Shell Structure of Thallium - Electrons per energy level


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Ground State Electronic Configuration of Thallium - neutral Thallium atom

The ground state electronic configuration of Neutral Thallium atom is 4f14 5d10 6s2 6p1. The portion of Thallium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as . 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 4f14 5d10 6s2 6p1, electrons in the outermost shell that determine the chemical properties of the element.

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Unabbreviated electronic configuration of neutral Thallium

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

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p1

Atomic Structure of Thallium

Thallium atomic radius is 156 pm, while it"s covalent radius is 148 pm.

Atomic Radius

156 pm (1.56 Å)

Atomic Volume 17.247535865 cm3
Covalent Radius 148 pm (1.48 Å)
Van der Waals Radius 196 pm
Neutron Cross Section 3.4 σa/barns

Atomic Spectrum of Thallium

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Thallium Chemical Properties: Thallium Ionization Energies and electron affinity

The electron affinity of Thallium is 19.2 kJ/mol

Valence 3
Electronegativity 1.62
ElectronAffinity 19.2 kJ/mol

Ionization Energy of Thallium

Refer to table below for Ionization energies of Thallium

Ionization energy number Enthalpy - kJ/mol
1 589.4
2 1971
3 2878

Thallium Physical Properties

Refer to below table for Thallium Physical Properties

Density 11.85 g/cm3
Molar Volume 17.247535865 cm3

Elastic Properties

Young Modulus 8 GPa
Shear Modulus 2.8 GPa
Bulk Modulus 43 GPa
Poisson Ratio 0.45

Hardness of Thallium - Tests to Measure of Hardness of Element

Mohs Hardness 1.2 MPa
Vickers Hardness N/A
Brinell Hardness 26.4 MPa

Thallium Electrical Properties

Thallium is Conductor of electricity. Refer to table below for the Electrical properties of Thallium

Electrical Conductivity 6.7×106 S/m
Resistivity 1.5×10-7 m Ω
Superconducting Point 2.38

Thallium Heat and Conduction Properties

Thermal Conductivity 46 W/(m K)
Thermal Expansion 0.0000299 K-1

Thallium Magnetic Properties

Magnetic Type Diamagnetic
Curie Point N/A
Mass Magnetic Susceptibility -3×10-9
Molar Magnetic Susceptibility -6.13×10-10
Volume Magnetic Susceptibility -3.56e-05

Optical Properties of Thallium

Refractive Index N/A

Acoustic Properties of Thallium

Speed of Sound 818 m/s

Thallium Thermal Properties - Enthalpies and thermodynamics

Refer to table below for Thermal properties of Thallium

Melting Point 577 K (304 °C)
Boiling Point 1746 K (1473 °C)
Critical Temperature N/A
Superconducting Point 2.38

Enthalpies of Thallium

Heat of Fusion 4.2 kJ/mol
Heat of Vaporization 165 kJ/mol
Heat of Combustion N/A

Thallium Isotopes - Nuclear Properties of Thallium

Isotopes of rhodium. Naturally occurring Thallium has 2 stable isotope - 203Tl, 205Tl.


Isotope Isotope Mass % Abundance T half Decay Mode
176Tl
177Tl
178Tl
179Tl
180Tl
181Tl
182Tl
183Tl
184Tl
185Tl
186Tl
187Tl
188Tl
189Tl
190Tl
191Tl
192Tl
193Tl
194Tl
195Tl
196Tl
197Tl
198Tl
199Tl
200Tl
201Tl
202Tl
203Tl 29.524% Stable N/A
204Tl
205Tl 70.476% Stable N/A
206Tl
207Tl
208Tl
209Tl
210Tl
211Tl
212Tl

Regulatory and Health - Health and Safety Parameters and Guidelines

CAS Number CAS7440-28-0
RTECS Number RTECSXG3425000
DOT Hazard Class N/A
DOT Numbers 1707
EU Number N/A
NFPA Fire Rating N/A
NFPA Hazards N/A
NFPA Health Rating N/A
NFPA Reactivity Rating N/A
Autoignition Point N/A
Flashpoint 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) CAS7440-28-0
CID Number CID5359464
Gmelin Number N/A
NSC Number N/A
RTECS Number RTECSXG3425000

Compare Thallium with all Group 13 elements

Thallium vs Boron Thallium vs Aluminium Thallium vs Gallium Thallium vs Indium Thallium vs Nihonium

Compare Thallium with all post-transition metal elements

Thallium vs Aluminium Thallium vs Gallium Thallium vs Indium Thallium vs Tin Thallium vs Lead Thallium vs Bismuth Thallium vs Nihonium Thallium vs Flerovium Thallium vs Moscovium Thallium vs Livermorium