Symbol
Tl
Cs
Group Number
131
0
17
👆🏻
Period Number
66
2
7
👆🏻
Block
p block
s block
Element Family
Post-Transition
Alkali
CAS Number
74402807440462
7429905
54386242
👆🏻
Space Group Name
P63/mmc
Im_ 3m
Space Group Number
194.00229.00
11
276
👆🏻
Interesting Facts
- Compounds of Thallium metal are highly Toxic.
- Thallium metal is being suspected as a human carcinogen.
Cesium is the most alkaline metal and is used in atomic clocks.
Sources
Found As a By-product, Ores of metals, Ores of Minerals
Earth's crust, Found in Minerals, Mining, Ores of Minerals
History
Who Discovered
William Crookes
Robert Bunsen and Gustav Kirchhoff
Discovery
In 1861
In 1860
Abundance
Abundance In Universe
0.00 %0.00 %
0
0.11
👆🏻
Abundance In Sun
0.00 %0.00 %
0
0.1
👆🏻
Abundance In Meteorites
0.00 %0.00 %
0
22
👆🏻
Abundance In Earth's Crust
0.00 %0.00 %
1E-37
8.1
👆🏻
Abundance In Oceans
0.00 %0.00 %
0
1.1
👆🏻
Abundance In Humans
0.00 %0.00 %
0
1.4
👆🏻
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.
- The most common use of cesium metal is as a drilling fluid. It is also used in optical glass manufacturing.
-
In vacuum tubes and radiation monitor equipment this metal is used as a catalyst promoter.
Industrial Uses
Chemical Industry
Aerospace Industry, Automobile Industry, Electrical Industry, Electronic Industry
Medical Uses
Medical Research
-
Other Uses
Alloys
Alloys
Biological Properties
Toxicity
Highly Toxic
Mildly Toxic
Present in Human Body
✔
✘
✔
✘
In Blood
0.00 Blood/mg dm-30.00 Blood/mg dm-3
0
1970
👆🏻
In Bone
0.00 p.p.m.0.05 p.p.m.
0
170000
👆🏻
Melting Point
303.50 °C28.50 °C
-38.83
3410
👆🏻
Boiling Point
1,457.00 °C678.40 °C
0
5660
👆🏻
Appearance
Physical State
Solid
Solid
Color
Silvery White
Silvery Gold
Luster
-
-
Hardness
Mohs Hardness
1.200.20
0.2
8.5
👆🏻
Brinell Hardness
26.50 MPa0.14 MPa
0.14
3490
👆🏻
Vickers Hardness
120.00 MPa0.14 MPa
0
3920
👆🏻
Speed of Sound
818.00 m/s1,630.00 m/s
818
16200
👆🏻
Optical Properties
Refractive Index
1.901.93
0.155
3.41
👆🏻
Reflectivity
8.00 %35.00 %
5
97
👆🏻
Allotropes
✔
✘
✔
✘
α Allotropes
-
-
β Allotropes
-
-
γ Allotropes
-
-
Chemical Formula
Tl
Cs
Isotopes
Known Isotopes
3236
0
38
👆🏻
Electronegativity
Pauling Electronegativity
1.620.79
0
2.6
👆🏻
Sanderson Electronegativity
2.250.22
0.22
2.56
👆🏻
Allred Rochow Electronegativity
1.440.86
0.86
1.9
👆🏻
Mulliken-Jaffe Electronegativity
1.960.62
0.62
2.48
👆🏻
Allen Electronegativity
1.790.66
0.659
2.7
👆🏻
Electropositivity
Pauling Electropositivity
2.383.21
1.46
3.3
👆🏻
Ionization Energies
1st Energy Level
589.40 kJ/mol375.70 kJ/mol
375.7
26130
👆🏻
2nd Energy Level
1,971.00 kJ/mol2,234.30 kJ/mol
392.8
28750
👆🏻
3rd Energy Level
2,878.00 kJ/mol3,400.00 kJ/mol
392.8
34230
👆🏻
4th Energy Level
5,890.00 kJ/mol375.70 kJ/mol
375.7
37066
👆🏻
5th Energy Level
5,890.00 kJ/mol3,750.00 kJ/mol
392
97510
👆🏻
6th Energy Level
5,890.00 kJ/mol3,750.00 kJ/mol
1007
105800
👆🏻
7th Energy level
5,890.00 kJ/mol3,750.00 kJ/mol
1007
114300
👆🏻
8th Energy Level
5,890.00 kJ/mol3,760.00 kJ/mol
730
125300
👆🏻
9th Energy Level
5,890.00 kJ/mol3,750.00 kJ/mol
1007
134700
👆🏻
10th Energy Level
5,890.00 kJ/mol3,757.00 kJ/mol
392
144300
👆🏻
11th Energy Level
5,890.00 kJ/mol3,757.00 kJ/mol
392
169988
👆🏻
12th Energy Level
5,890.00 kJ/mol3,750.00 kJ/mol
0
189368
👆🏻
13th Energy Level
5,890.00 kJ/mol3,750.00 kJ/mol
1007
76015
👆🏻
14th Energy Level
5,890.00 kJ/mol3,750.00 kJ/mol
380
86450
👆🏻
15th Energy Level
58,900.00 kJ/mol37,500.00 kJ/mol
33000
100700
👆🏻
16th Energy Level
58,900.00 kJ/mol375.70 kJ/mol
375.7
109480
👆🏻
17th Energy Level
589.40 kJ/mol375.70 kJ/mol
375.7
122200
👆🏻
18th Energy Level
5,890.00 kJ/mol3,757.00 kJ/mol
0
134810
👆🏻
19th Energy Level
589.40 kJ/mol375.70 kJ/mol
375.7
148700
👆🏻
20th Energy Level
589.00 kJ/mol375.00 kJ/mol
0
171200
👆🏻
21st Energy Level
589.40 kJ/mol375.70 kJ/mol
375.7
179100
👆🏻
22nd Energy Level
589.00 kJ/mol375.00 kJ/mol
330
184900
👆🏻
23rd Energy Level
589.40 kJ/mol375.70 kJ/mol
357.6
198800
👆🏻
24th Energy Level
589.40 kJ/mol375.70 kJ/mol
297.3
195200
👆🏻
25th Energy Level
589.40 kJ/mol375.70 kJ/mol
0
121900
👆🏻
26th Energy Level
589.40 kJ/mol375.70 kJ/mol
357.6
127700
👆🏻
27th Energy Level
589.40 kJ/mol375.70 kJ/mol
0
133800
👆🏻
28th Energy Level
589.40 kJ/mol375.70 kJ/mol
297.3
139800
👆🏻
29th Energy Level
589.40 kJ/mol375.70 kJ/mol
0
148100
👆🏻
30th Energy Level
589.40 kJ/mol375.70 kJ/mol
0
154500
👆🏻
Electrochemical Equivalent
7.63 g/amp-hr4.96 g/amp-hr
0.16812
8.3209
👆🏻
Electron Work Function
3.84 eV2.14 eV
2.14
6
👆🏻
Other Chemical Properties
Corrosion, Ionization, Radioactive Isotopes, Solubility
Chemical Stability, Corrosion, Ionization, Radioactive Isotopes, Solubility
Atomic Number
8155
3
117
👆🏻
Electron Configuration
[Xe] 4f14 5d10 6s2 6p1
[Xe] 6s1
Crystal Structure
Hexagonal Close Packed (HCP)
Body Centered Cubic (BCC)
Crystal Lattice
Atom
Number of Protons
8155
3
117
👆🏻
Number of Neutrons
12378
4
285
👆🏻
Number of Electrons
8155
3
117
👆🏻
Radius of an Atom
Atomic Radius
170.00 pm265.00 pm
0
348
👆🏻
Covalent Radius
145.00 pm244.00 pm
0
260
👆🏻
Van der Waals Radius
196.00 pm343.00 pm
0
348
👆🏻
Atomic Weight
204.38 amu132.91 amu
6.94
294
👆🏻
Atomic Volume
17.20 cm3/mol71.07 cm3/mol
1.39
71.07
👆🏻
Adjacent Atomic Numbers
Previous Element
Next Element
Valence Electron Potential
9.60 (-eV)8.62 (-eV)
0
392.42
👆🏻
Lattice Constant
345.66 pm614.10 pm
0
891.25
👆🏻
Lattice Angles
π/2, π/2, 2 π/3
π/2, π/2, π/2
Lattice C/A Ratio
1.601.87
0.423
1.9
👆🏻
Density
Density At Room Temperature
11.85 g/cm31.93 g/cm3
0.534
40.7
👆🏻
Density When Liquid (at m.p.)
11.22 g/cm31.84 g/cm3
0.512
41
👆🏻
Tensile Strength
47.00 MPa15.00 MPa
0.1
11000
👆🏻
Viscosity
0.000.00
1.5E-05
0.0035
👆🏻
Vapor Pressure
Vapor Pressure at 1000 K
16.90 (Pa)0.00 (Pa)
0
121
👆🏻
Vapor Pressure at 2000 K
0.00 (Pa)0.00 (Pa)
0
774
👆🏻
Elasticity properties
Shear Modulus
2.80 GPa30.00 GPa
1.3
222
👆🏻
Bulk Modulus
43.00 GPa1.60 GPa
0
462
👆🏻
Young's Modulus
8.00 GPa1.70 GPa
0
528
👆🏻
Poisson Ratio
0.450.35
0.032
0.47
👆🏻
Other Mechanical Properties
Ductile, Sectile
Ductile
Magnetic Characteristics
Specific Gravity
11.851.87
0.53
4500
👆🏻
Magnetic Ordering
Diamagnetic
Paramagnetic
Permeability
0.00 H/m0.00 H/m
1.25643E-06
0.0063
👆🏻
Susceptibility
0.000.00
-0.000166
200000
👆🏻
Electrical Properties
Electrical Property
Conductor
Semiconductor
Resistivity
0.18 nΩ·m205.00 nΩ·m
0.1
961
👆🏻
Electrical Conductivity
0.06 106/cm Ω0.05 106/cm Ω
0
0.63
👆🏻
Electron Affinity
19.20 kJ/mol45.50 kJ/mol
0
222.8
👆🏻
Specific Heat
0.13 J/(kg K)0.24 J/(kg K)
0.1
3.6
👆🏻
Molar Heat Capacity
26.32 J/mol·K32.21 J/mol·K
13.1
62.7
👆🏻
Thermal Conductivity
46.10 W/m·K35.90 W/m·K
0
429
👆🏻
Critical Temperature
577.00 K1,938.00 K
26.3
3695
👆🏻
Thermal Expansion
29.90 µm/(m·K)97.00 µm/(m·K)
4.5
97
👆🏻
Enthalpy
Enthalpy of Vaporization
162.10 kJ/mol65.90 kJ/mol
7.32
799.1
👆🏻
Enthalpy of Fusion
4.27 kJ/mol2.10 kJ/mol
2.1
35.23
👆🏻
Enthalpy of Atomization
179.90 kJ/mol78.20 kJ/mol
61.5
837
👆🏻
Standard Molar Entropy
64.20 J/mol.K85.20 J/mol.K
9.5
198.1
👆🏻