Thallium

Thallium
Thallium block | Image: Learnool

Thallium (Tl) is a chemical element of the periodic table, located in the group 13 and the period 6, and has the atomic number 81. It is a soft, malleable, lustrous, silvery-grey post transition metal, whose name comes from the Greek word “thallos”, which means green twig. It is highly toxic and is not available freely in nature. It is a member of the boron group.

On periodic table

group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
period
1 1
H
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Hydrogen
2
He
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Helium
2 3
Li
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Lithium
4
Be
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Beryllium
5
B
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Boron
6
C
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Carbon
7
N
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Nitrogen
8
O
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Oxygen
9
F
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Fluorine
10
Ne
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Neon
3 11
Na
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Sodium
12
Mg
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Magnesium
13
Al
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Aluminium
14
Si
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Silicon
15
P
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Phosphorus
16
S
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Sulfur
17
Cl
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Chlorine
18
Ar
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Argon
4 19
K
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Potassium
20
Ca
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Calcium
21
Sc
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Scandium
22
Ti
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Titanium
23
V
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Vanadium
24
Cr
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Chromium
25
Mn
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Manganese
26
Fe
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Iron
27
Co
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Cobalt
28
Ni
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Nickel
29
Cu
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Copper
30
Zn
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Zinc
31
Ga
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Gallium
32
Ge
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Germanium
33
As
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Arsenic
34
Se
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Selenium
35
Br
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Bromine
36
Kr
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Krypton
5 37
Rb
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Rubidium
38
Sr
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Strontium
39
Y
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Yttrium
40
Zr
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Zirconium
41
Nb
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Niobium
42
Mo
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Molybdenum
43
Tc
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Technetium
44
Ru
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Ruthenium
45
Rh
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Rhodium
46
Pd
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Palladium
47
Ag
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Silver
48
Cd
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Cadmium
49
In
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Indium
50
Sn
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Tin
51
Sb
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Antimony
52
Te
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Tellurium
53
I
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Iodine
54
Xe
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Xenon
6 55
Cs
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Caesium
56
Ba
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Barium
72
Hf
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Hafnium
73
Ta
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Tantalum
74
W
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Tungsten
75
Re
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Rhenium
76
Os
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Osmium
77
Ir
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Iridium
78
Pt
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Platinum
79
Au
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Gold
80
Hg
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Mercury
81
Tl
Thallium
82
Pb
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Lead
83
Bi
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Bismuth
84
Po
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Polonium
85
At
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Astatine
86
Rn
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Radon
7 87
Fr
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Francium
88
Ra
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Radium
104
Rf
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Rutherfordium
105
Db
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Dubnium
106
Sg
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Seaborgium
107
Bh
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Bohrium
108
Hs
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Hassium
109
Mt
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Meitnerium
110
Ds
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Darmstadtium
111
Rg
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Roentgenium
112
Cn
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Copernicium
113
Nh
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Nihonium
114
Fl
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Flerovium
115
Mc
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Moscovium
116
Lv
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Livermorium
117
Ts
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Tennessine
118
Og
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Oganesson
57
La
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Lanthanum
58
Ce
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Cerium
59
Pr
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Praseodymium
60
Nd
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Neodymium
61
Pm
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Promethium
62
Sm
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Samarium
63
Eu
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Europium
64
Gd
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Gadolinium
65
Tb
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Terbium
66
Dy
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Dysprosium
67
Ho
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Holmium
68
Er
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Erbium
69
Tm
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Thulium
70
Yb
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Ytterbium
71
Lu
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Lutetium
89
Ac
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Actinium
90
Th
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Thorium
91
Pa
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Protactinium
92
U
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Uranium
93
Np
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Neptunium
94
Pu
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Plutonium
95
Am
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Americium
96
Cm
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Curium
97
Bk
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Berkelium
98
Cf
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Californium
99
Es
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Einsteinium
100
Fm
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Fermium
101
Md
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Mendelevium
102
No
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Nobelium
103
Lr
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Lawrencium
– p block

Thallium is a p-block element, situated in the thirteenth column (boron group) of the periodic table, below indium (In), and is denoted by the atomic number 81 and chemical symbol Tl.

Element information

Thallium Element
Thallium appearance | Image: Wikipedia
Thallium Periodic Table
Thallium location on periodic table | Image: Learnool
Thallium is found in the sixth row of the periodic table below the indium element.
Origin of name Greek word “thallos” (which means green twig)
Symbol Tl
Atomic number (Z) 81
Atomic mass 204.3833 u
Block p-block
Group 13 (boron group)
Period 6
Classification Post-transition metal
Atomic radius 170 pm
Covalent radius 145±7 pm
Van der Waals radius 196 pm
Melting point 304 ℃, 579 ℉, 577 K
Boiling point 1473 ℃, 2683 ℉, 1746 K
Electron configuration [Xe] 4f14 5d10 6s2 6p1
Electrons per shell 2, 8, 18, 32, 18, 3
Learn how to draw: Thallium Bohr model
Crystal structure Hexagonal close-packed (hcp)
Phase at r.t Solid
Density near r.t 11.85 g/cm3
Main isotopes Thallium-203, Thallium-205
Natural occurrence Primordial
Oxidation state +1, +3
Electronegativity (Pauling scale) 1.62
Protons
Neutrons
Electrons
81
123
81
Learn how to find: Thallium protons neutrons electrons
Valence electrons 3
Learn how to find: Thallium valence electrons
CAS number 7440-28-0
Discovered by William Crookes in 1861

History

William Crookes | Image: Chemistry World

Thallium was discovered in 1861 by Sir William Crookes, an English chemist, while he was attempting to extract selenium from the byproducts of sulfuric acid production. Thallium was named after the Greek word “thallos,” which means “a green shoot or twig,” due to the green line in its atomic spectrum.

In the early 20th century, thallium was used as a rodenticide and insecticide. However, it was later discovered to be highly toxic to humans and was banned for these uses. Today, thallium has a few specialized uses in industry, including in the production of optical lenses and as a radiation source in portable X-ray devices.

Occurrence and production

Thallium is a relatively rare element in the Earth’s crust, occurring at an estimated concentration of 0.7 milligrams per kilogram. The primary source of thallium is the minerals crookesite, lorándite and hutchinsonite, although it is also found in small quantities in other sulfide and selenide minerals. Thallium can also be found in some soils, sediments, and waters as a result of human activities such as coal burning, metal smelting, and waste disposal.

Thallium is typically produced as a byproduct of zinc, copper, and lead refining processes, with the majority of production taking place in China. It can also be obtained through the electrolytic deposition of thallium sulfate, or by treating thallium-containing minerals with sulfuric acid. Another method involves the reaction of thallium oxide with hydrogen gas at high temperatures.

The production of thallium is relatively small compared to other metals, with an estimated global production of around 30-40 tonnes per year. However, due to its toxicity, thallium is highly regulated and controlled in many countries, and its use is limited to specific applications such as electronics, pharmaceuticals, and research.

Properties

Thallium is a soft, silvery-white metal that tarnishes quickly when exposed to air.

It has a low melting point of 304 ℃ and a boiling point of 1473 ℃.

Thallium is a highly toxic element that can cause serious health problems even at low exposure levels.

It is a relatively dense element with a density of 11.85 g/cm3.

Thallium is a good conductor of electricity and is used in some electrical devices.

It has two stable isotopes and several radioactive isotopes.

Thallium has some unusual properties, such as its ability to form stable complexes with organic molecules and its tendency to form anions in solution.

Thallium has a unique spectral signature that can be used to identify it in astronomical observations.

Applications

Thallium is a highly toxic element that is not widely used in commercial applications due to its toxicity. However, it has some limited uses in certain fields.

Thallium compounds have been used in medicine as radioisotopes for diagnostic imaging of the heart, lungs, and brain. They are also used in cancer radiation therapy.

Thallium oxide is used as a material for producing glass with a high index of refraction, which is used in lenses for cameras and other optical instruments. Thallium is also used in photocells and as a dopant in semiconductors.

Thallium is used in the production of specialized crystals for use in infrared optics, as well as in the production of specialized glass for use in fiber optics.

Despite its toxicity, thallium has been used as an insecticide and rodenticide. However, its use in these applications has been largely discontinued due to safety concerns.

Thallium is used in the production of certain types of alloys and in the production of high-temperature superconductors. It is also used as a catalyst in certain chemical reactions.

Interesting facts

The name thallium is derived from the Greek word “thallos” which means “a green shoot or twig”.

Thallium has the lowest melting point of any metal.

Thallium is extremely toxic, and its use in rat poison has been banned in many countries.

Thallium can be used in the treatment of ringworm, a fungal infection, and as a contrast agent in medical imaging.

Thallium has been used in the past for homicide and suicide due to its high toxicity and tastelessness.

Thallium is used in the manufacture of high-refractive-index glass for camera lenses, prisms, and spectacles.

Thallium sulfate was once used as a reagent in the detection of potassium ions in biological samples.

Related

More elements

s block
p block
d block
f block
Barium Aluminium Bohrium Actinium
Beryllium Antimony Cadmium Americium
Caesium Argon Chromium Berkelium
Calcium Arsenic Cobalt Californium
Francium Astatine Copernicium Cerium
Helium Bismuth Copper Curium
Hydrogen Boron Darmstadtium Dysprosium
Lithium Bromine Dubnium Einsteinium
Magnesium Carbon Gold Erbium
Potassium Chlorine Hafnium Europium
Radium Flerovium Hassium Fermium
Rubidium Fluorine Iridium Gadolinium
Sodium Gallium Iron Holmium
Strontium Germanium Lawrencium Lanthanum
Indium Lutetium Mendelevium
Iodine Manganese Neodymium
Krypton Meitnerium Neptunium
Lead Mercury Nobelium
Livermorium Molybdenum Plutonium
Moscovium Nickel Praseodymium
Neon Niobium Promethium
Nihonium Osmium Protactinium
Nitrogen Palladium Samarium
Oganesson Platinum Terbium
Oxygen Rhenium Thorium
Phosphorus Rhodium Thulium
Polonium Roentgenium Uranium
Radon Ruthenium Ytterbium
Selenium Rutherfordium
Silicon Scandium
Sulfur Seaborgium
Tellurium Silver
Tennessine Tantalum
Thallium Technetium
Tin Titanium
Xenon Tungsten
Vanadium
Yttrium
Zinc
Zirconium

External links

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Learnool.com was founded by Deep Rana, who is a mechanical engineer by profession and a blogger by passion. He has a good conceptual knowledge on different educational topics and he provides the same on this website. He loves to learn something new everyday and believes that the best utilization of free time is developing a new skill.

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