Symbol
La
  
Tl
  
Group Number
Not Available
  
Period Number
6
  
6
  
Block
f block
  
p block
  
Element Family
Lanthanide
  
Post-Transition
  
Space Group Name
P63/mmc
  
P63/mmc
  
Interesting Facts
- Lanthanum metal is highly malleable, ductile and sectile.
- If exposed to air Lanthanum metal oxidizes rapidly.
  
- Compounds of Thallium metal are highly Toxic.
- Thallium metal is being suspected as a human carcinogen.
  
Sources
Found in Minerals, Mining, Ores of Minerals
  
Found As a By-product, Ores of metals, Ores of Minerals
  
History
  
  
Who Discovered
Carl Gustaf Mosander
  
William Crookes
  
Discovery
In 1838
  
In 1861
  
Abundance
  
  
Abundance In Sun
~0.0000002 %
  
25
~0.0000001 %
  
26
Abundance In Earth's Crust
Uses & Benefits
- It has no commercial uses, but its alloys are in high demand. Lanthanum and Nickel alloy is used for the hydrogen gas storage.
- The best-known use for mischmetal alloy of Lanthanum is; as a ‘flints’ for cigarette lighters.
  
- 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
Electrical Industry, Electronic Industry
  
Chemical Industry
  
Medical Uses
NA
  
Medical Research
  
Other Uses
Alloys, Mirror Manufacturing
  
Alloys
  
Biological Properties
  
  
Toxicity
Low Toxic
  
Highly Toxic
  
Present in Human Body
Yes
  
Yes
  
In Blood
Not Available
  
0.00 Blood/mg dm-3
  
34
In Bone
0.08 p.p.m.
  
24
0.00 p.p.m.
  
33
Boiling Point
3,469.00 °C
  
18
1,457.00 °C
  
99+
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Silvery White
  
Silvery White
  
Luster
NA
  
NA
  
Hardness
  
  
Vickers Hardness
Not Available
  
Speed of Sound
2,475.00 m/s
  
37
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 Formula
La
  
Tl
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Not Available
  
Allred Rochow Electronegativity
Mulliken-Jaffe Electronegativity
Not Available
  
Allen Electronegativity
Not Available
  
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
538.10 kJ/mol
  
99+
589.40 kJ/mol
  
99+
2nd Energy Level
1,067.00 kJ/mol
  
99+
1,971.00 kJ/mol
  
14
3rd Energy Level
1,850.30 kJ/mol
  
99+
2,878.00 kJ/mol
  
32
4th Energy Level
4,819.00 kJ/mol
  
22
Not Available
  
5th Energy Level
5,940.00 kJ/mol
  
25
Not Available
  
Electrochemical Equivalent
1.73 g/amp-hr
  
99+
7.63 g/amp-hr
  
2
Other Chemical Properties
Ionization, Radioactive Isotopes, Solubility
  
Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Electron Configuration
[Xe] 5d2 6s2
  
[Xe] 4f14 5d10 6s2 6p1
  
Crystal Structure
Double Hexagonal Close Packed (DHCP)
  
Hexagonal Close Packed (HCP)
  
Crystal Lattice
DHCP-Crystal-Structure-of-Lanthanum.jpg#100
  
BCC-Crystal-Structure-.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Weight
138.91 amu
  
99+
Atomic Volume
20.73 cm3/mol
  
16
17.20 cm3/mol
  
31
Adjacent Atomic Numbers
  
  
Valence Electron Potential
40.71 (-eV)
  
99+
9.60 (-eV)
  
99+
Lattice Angles
π/2, π/2, 2 π/3
  
π/2, π/2, 2 π/3
  
Density
  
  
Density At Room Temperature
6.16 g/cm3
  
99+
11.85 g/cm3
  
31
Density When Liquid (at m.p.)
5.94 g/cm3
  
99+
11.22 g/cm3
  
13
Tensile Strength
Not Available
  
Not Available
  
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Vapor Pressure at 1000 K
Not Available
  
Vapor Pressure at 2000 K
Not Available
  
Elasticity properties
  
  
Other Mechanical Properties
Ductile
  
Ductile, Sectile
  
Magnetic Characteristics
  
  
Magnetic Ordering
Paramagnetic
  
Diamagnetic
  
Electrical Properties
  
  
Electrical Property
Conductor
  
Conductor
  
Electrical Conductivity
0.01 106/cm Ω
  
99+
0.06 106/cm Ω
  
32
Electron Affinity
48.00 kJ/mol
  
23
19.20 kJ/mol
  
32
Specific Heat
0.19 J/(kg K)
  
32
0.13 J/(kg K)
  
39
Molar Heat Capacity
27.11 J/mol·K
  
21
26.32 J/mol·K
  
29
Thermal Conductivity
13.40 W/m·K
  
99+
46.10 W/m·K
  
33
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
12.10 µm/(m·K)
  
32
29.90 µm/(m·K)
  
12
Enthalpy
  
  
Enthalpy of Vaporization
399.60 kJ/mol
  
17
162.10 kJ/mol
  
99+
Enthalpy of Fusion
6.20 kJ/mol
  
99+
4.27 kJ/mol
  
99+
Enthalpy of Atomization
431.00 kJ/mol
  
16
179.90 kJ/mol
  
99+
Standard Molar Entropy
56.90 J/mol.K
  
23
64.20 J/mol.K
  
19