Lead vs Thallium
Periodic Table
Symbol
Pb
Tl
Group Number
14
4
13
5
Period Number
6
6
Block
p block
p block
Element Family
Post-Transition
Post-Transition
CAS Number
7439921
99+
7440280
99+
Space Group Name
Fm_ 3m
P63/mmc
Space Group Number
225.00
2
194.00
5
Facts
Interesting Facts
- Galena mineral contains almost 87% of Lead metal in it, Galena is sulfide mineral.
- The best available source of Lead metal today is by recycling automobile batteries.
- Compounds of Thallium metal are highly Toxic.
- Thallium metal is being suspected as a human carcinogen.
Sources
Earth's crust, Found in Minerals, Mining, Ores of metals, Ores of Minerals
Found As a By-product, Ores of metals, Ores of Minerals
History
Who Discovered
Unknown
William Crookes
Discovery
In Middle Easterns (7000 BCE)
In 1861
Abundance
Abundance In Universe
1 * 10-6 %
16
5 * 10-9 %
32
Abundance In Sun
~0.000001 %
18
~0.0000001 %
26
Abundance In Meteorites
0.00 %
23
0.00 %
99+
Abundance In Earth's Crust
0.00 %
26
0.00 %
99+
Abundance In Oceans
0.00 %
22
0.00 %
34
Abundance In Humans
0.00 %
8
Not Available
Uses
Uses & Benefits
- It is also used in insecticides, hair dyes and as an anti-knocking additive for petrol. But all these are banned by the government as Lead metal is known for detrimental to health.
- 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.
Industrial Uses
Chemical Industry, Electrical Industry, Electronic Industry
Chemical Industry
Medical Uses
Surgical Instruments Manufacturing
Medical Research
Other Uses
Alloys
Alloys
Biological Properties
Toxicity
Toxic
Highly Toxic
Present in Human Body
Yes
Yes
In Blood
0.21 Blood/mg dm-3
11
0.00 Blood/mg dm-3
34
In Bone
30.00 p.p.m.
10
0.00 p.p.m.
33
Physical Properties
Melting Point
327.50 °C
99+
303.50 °C
99+
Boiling Point
1,740.00 °C
99+
1,457.00 °C
99+
Appearance
Physical State
Solid
Solid
Color
Gray
Silvery White
Luster
Metallic
NA
Hardness
Mohs Hardness
1.50
18
1.20
20
Brinell Hardness
38.00 MPa
99+
26.50 MPa
99+
Speed of Sound
1,190.00 m/s
99+
818.00 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 Properties
Chemical Formula
Pb
Tl
Isotopes
Known Isotopes
35
4
32
7
Electronegativity
Pauling Electronegativity
1.87
13
1.62
21
Sanderson Electronegativity
2.29
4
2.25
5
Allred Rochow Electronegativity
1.55
11
1.44
17
Mulliken-Jaffe Electronegativity
2.41
2
1.96
6
Allen Electronegativity
1.85
8
1.79
13
Electropositivity
Pauling Electropositivity
1.67
99+
2.38
33
Ionization Energies
1st Energy Level
715.60 kJ/mol
31
589.40 kJ/mol
99+
2nd Energy Level
1,450.50 kJ/mol
99+
1,971.00 kJ/mol
14
3rd Energy Level
3,081.50 kJ/mol
23
2,878.00 kJ/mol
32
4th Energy Level
4,083.00 kJ/mol
35
Not Available
5th Energy Level
6,640.00 kJ/mol
20
Not Available
Electrochemical Equivalent
3.87 g/amp-hr
9
7.63 g/amp-hr
2
Electron Work Function
4.25 eV
21
3.84 eV
28
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes
Corrosion, Ionization, Radioactive Isotopes, Solubility
Atomic Properties
Atomic Number
82
34
81
35
Electron Configuration
[Xe] 4f14 5d10 6s2 6p2
[Xe] 4f14 5d10 6s2 6p1
Crystal Structure
Face Centered Cubic (FCC)
Hexagonal Close Packed (HCP)
Crystal Lattice
FCC-Crystal-Structure-of-Lead.jpg#100
BCC-Crystal-Structure-.jpg#100
Atom
Number of Protons
82
34
81
35
Number of Neutrons
125
19
123
20
Number of Electrons
82
34
81
35
Radius of an Atom
Atomic Radius
175.00 pm
19
170.00 pm
22
Covalent Radius
146.00 pm
38
145.00 pm
39
Van der Waals Radius
202.00 pm
27
196.00 pm
30
Atomic Weight
207.20 amu
30
204.38 amu
31
Atomic Volume
18.17 cm3/mol
27
17.20 cm3/mol
31
Adjacent Atomic Numbers
Valence Electron Potential
24.20 (-eV)
99+
9.60 (-eV)
99+
Lattice Constant
495.08 pm
16
345.66 pm
99+
Lattice Angles
π/2, π/2, π/2
π/2, π/2, 2 π/3
Lattice C/A Ratio
Not Available
1.60
6
Mechanical Properties
Density
Density At Room Temperature
11.34 g/cm3
33
11.85 g/cm3
31
Density When Liquid (at m.p.)
10.66 g/cm3
15
11.22 g/cm3
13
Tensile Strength
12.00 MPa
20
Not Available
Viscosity
Not Available
Not Available
Vapor Pressure
Vapor Pressure at 1000 K
1.64 (Pa)
7
16.90 (Pa)
5
Elasticity properties
Shear Modulus
5.60 GPa
99+
2.80 GPa
99+
Bulk Modulus
46.00 GPa
24
43.00 GPa
28
Young's Modulus
16.00 GPa
99+
8.00 GPa
99+
Poisson Ratio
0.44
3
0.45
2
Other Mechanical Properties
Ductile, Malleable
Ductile, Sectile
Magnetic Properties
Magnetic Characteristics
Specific Gravity
11.35
25
11.85
22
Magnetic Ordering
Diamagnetic
Diamagnetic
Electrical Properties
Electrical Property
Poor Conductor
Conductor
Resistivity
208.00 nΩ·m
16
0.18 nΩ·m
99+
Electrical Conductivity
0.05 106/cm Ω
36
0.06 106/cm Ω
32
Electron Affinity
35.10 kJ/mol
28
19.20 kJ/mol
32
Thermal Properties
Specific Heat
0.13 J/(kg K)
39
0.13 J/(kg K)
39
Molar Heat Capacity
26.65 J/mol·K
26
26.32 J/mol·K
29
Thermal Conductivity
35.30 W/m·K
38
46.10 W/m·K
33
Critical Temperature
Not Available
Not Available
Thermal Expansion
28.90 µm/(m·K)
13
29.90 µm/(m·K)
12
Enthalpy
Enthalpy of Vaporization
179.40 kJ/mol
99+
162.10 kJ/mol
99+
Enthalpy of Fusion
4.77 kJ/mol
99+
4.27 kJ/mol
99+
Enthalpy of Atomization
194.60 kJ/mol
99+
179.90 kJ/mol
99+
Standard Molar Entropy
64.80 J/mol.K
17
64.20 J/mol.K
19
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