Holmium

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Holmium is a chemical element with the symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a relatively soft and malleable silvery-white metallic element, which is stable in dry air at room temperature. A rare earth metal, it is found in the minerals monazite and gadolinite.

 

General
Name, Symbol, Number holmium, Ho, 67
Chemical series lanthanides
Group, Period, Block n/a, 6, f
Appearance silvery white
Standard atomic weight 164.93032(2) g·mol-1
Electrons per shell 2, 8, 18, 29, 8, 2
Physical properties
Phase solid
Density (near r.t.) 8.79 g·cm−3
Liquid density at m.p. 8.34 g·cm−3
Melting point 1734K
(1461°C, 2662°F)
Boiling point 2993K
(2720°C, 4928°F)
Heat of fusion 17.0 kJ·mol-1
Heat of vaporization 265 kJ·mol-1
Heat capacity (25°C) 27.15 J·mol-1·K-1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 1432 1584 (1775) (2040) (2410) (2964)
Atomic properties
Crystal structure hexagonal
Oxidation states 3
(basic oxide)
Electronegativity 1.23 (Pauling scale)
Ionization energies
(more)
1st: 581.0 kJ·mol-1
2nd: 1140 kJ·mol-1
3rd: 2204 kJ·mol-1
Atomic radius 175 pm
Miscellaneous
Magnetic ordering paramagnetic
Electrical resistivity (r.t.) (poly) 814 nΩ·m
Thermal conductivity (300K) 16.2 W·m-1·K-1
Thermal expansion (r.t.) (poly)
11.2 µm/(m·K)
Speed of sound (thin rod) (20 °C) 2760 m/s
Young's modulus 64.8 GPa
Shear modulus 26.3 GPa
Bulk modulus 40.2 GPa
Poisson ratio 0.231
Vickers hardness 481 MPa
Brinell hardness 746 MPa
CAS registry number 7440-60-0

 

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