Symbol
Tl
  
In
  
Period Number
6
  
5
  
Block
p block
  
p block
  
Element Family
Post-Transition
  
Post-Transition
  
Space Group Name
P63/mmc
  
I4/mmm
  
Interesting Facts
- Compounds of Thallium metal are highly Toxic.
- Thallium metal is being suspected as a human carcinogen.
  
- Luster of Indium is bright in nature.
- Reich and richer were looking for thallium in zinc metal and they discovered Indium metal.
  
Sources
Found As a By-product, Ores of metals, Ores of Minerals
  
Mining, Ores of metals
  
History
  
  
Who Discovered
William Crookes
  
Ferdinand Reich and Hieronymous Theodor Richter
  
Discovery
In 1861
  
In 1863
  
Abundance
  
  
Abundance In Sun
~0.0000001 %
  
26
~0.0000004 %
  
23
Abundance In Earth's Crust
Uses & Benefits
- Thallium is a toxic metal and hence it has limited uses. Thallium metal is mostly used for producing photoelectric cells.
- In thermometer’s mercury alloy has 8% of thallium, as it has a melting point lower than 20°C.
  
- It is used to produce indium tin oxide (ITO), it is used in manufacturing touch screens, flat screen TVs and solar panels.
- Its nitride, phosphide and antimonide are used in transistors and microchips.
  
Industrial Uses
Chemical Industry
  
Aerospace Industry, Automobile Industry
  
Medical Uses
Medical Research
  
Medical Research
  
Other Uses
Alloys
  
Alloys, In Nuclear Reactors
  
Biological Properties
  
  
Toxicity
Highly Toxic
  
Non Toxic
  
Present in Human Body
Yes
  
Yes
  
In Blood
0.00 Blood/mg dm-3
  
34
Not Available
  
In Bone
0.00 p.p.m.
  
33
Not Available
  
Boiling Point
1,457.00 °C
  
99+
2,000.00 °C
  
99+
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Silvery White
  
Silvery Gray
  
Luster
NA
  
Lustrous
  
Hardness
  
  
Speed of Sound
818.00 m/s
  
99+
1,215.00 m/s
  
99+
Optical Properties
  
  
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
Tl
  
In
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Allred Rochow Electronegativity
Mulliken-Jaffe Electronegativity
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
589.40 kJ/mol
  
99+
558.30 kJ/mol
  
99+
2nd Energy Level
1,971.00 kJ/mol
  
14
1,820.70 kJ/mol
  
18
3rd Energy Level
2,878.00 kJ/mol
  
32
2,704.00 kJ/mol
  
39
4th Energy Level
Not Available
  
5,210.00 kJ/mol
  
17
Electrochemical Equivalent
7.63 g/amp-hr
  
2
1.43 g/amp-hr
  
99+
Other Chemical Properties
Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Ionization, Radioactive Isotopes, Radioactivity, Solubility
  
Electron Configuration
[Xe] 4f14 5d10 6s2 6p1
  
[Kr] 4d10 5s2 5p1
  
Crystal Structure
Hexagonal Close Packed (HCP)
  
Tetragonal (TETR)
  
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
  
TETR-Crystal-Structure-of-Indium.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Weight
114.82 amu
  
99+
Atomic Volume
17.20 cm3/mol
  
31
15.70 cm3/mol
  
33
Adjacent Atomic Numbers
  
  
Valence Electron Potential
9.60 (-eV)
  
99+
54.00 (-eV)
  
25
Lattice Angles
π/2, π/2, 2 π/3
  
π/2, π/2, π/2
  
Lattice C/A Ratio
Not Available
  
Density
  
  
Density At Room Temperature
11.85 g/cm3
  
31
7.31 g/cm3
  
99+
Density When Liquid (at m.p.)
11.22 g/cm3
  
13
Tensile Strength
Not Available
  
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Elasticity properties
  
  
Shear Modulus
Not Available
  
Bulk Modulus
Not Available
  
Poisson Ratio
Not Available
  
Other Mechanical Properties
Ductile, Sectile
  
Ductile, Malleable
  
Magnetic Characteristics
  
  
Magnetic Ordering
Diamagnetic
  
Diamagnetic
  
Electrical Properties
  
  
Electrical Property
Conductor
  
Conductor
  
Electrical Conductivity
0.06 106/cm Ω
  
32
0.12 106/cm Ω
  
17
Electron Affinity
19.20 kJ/mol
  
32
28.90 kJ/mol
  
31
Specific Heat
0.13 J/(kg K)
  
39
0.23 J/(kg K)
  
27
Molar Heat Capacity
26.32 J/mol·K
  
29
26.74 J/mol·K
  
25
Thermal Conductivity
46.10 W/m·K
  
33
81.80 W/m·K
  
21
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
29.90 µm/(m·K)
  
12
32.10 µm/(m·K)
  
9
Enthalpy
  
  
Enthalpy of Vaporization
162.10 kJ/mol
  
99+
226.40 kJ/mol
  
40
Enthalpy of Fusion
4.27 kJ/mol
  
99+
3.28 kJ/mol
  
99+
Enthalpy of Atomization
179.90 kJ/mol
  
99+
242.70 kJ/mol
  
99+
Standard Molar Entropy
64.20 J/mol.K
  
19
57.80 J/mol.K
  
22