Holmium (Ho)

Atomic Model Details

Holmium (Ho) is a rare earth element, specifically a lanthanide.

Atomic Symbol: Ho
Atomic Number (Z): 67
Atomic Mass (A): 164.93033 u (for the most stable and naturally abundant isotope, ¹⁶⁵Ho)
Number of Protons: 67 (equal to atomic number)
Number of Electrons: 67 (in a neutral atom)
Number of Neutrons: 98 (for ¹⁶⁵Ho: Mass Number - Atomic Number = 165 - 67)
Atomic Radius (Metallic): 177 pm

The electronic configuration dictates the chemical behavior of an element.

Electronic Configuration: [Xe] 4f¹¹ 6s²
- This indicates that Holmium has the electron configuration of Xenon (Xe) followed by 11 electrons in the 4f subshell and 2 electrons in the 6s subshell.
- Expanded Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹¹ 5s² 5p⁶ 6s²
Shell-wise Electron Distribution:
- K-shell (n=1): 2 electrons (1s²)
- L-shell (n=2): 8 electrons (2s² 2p⁶)
- M-shell (n=3): 18 electrons (3s² 3p⁶ 3d¹⁰)
- N-shell (n=4): 29 electrons (4s² 4p⁶ 4d¹⁰ 4f¹¹)
- O-shell (n=5): 8 electrons (5s² 5p⁶)
- P-shell (n=6): 2 electrons (6s²)

Holmium’s position as a lanthanide in the f-block influences its periodic trends.

First Ionization Enthalpy (IE₁): Approximately 581 kJ/mol
Second Ionization Enthalpy (IE₂): Approximately 1140 kJ/mol
Third Ionization Enthalpy (IE₃): Approximately 2161 kJ/mol
Trend: Lanthanides generally have relatively low ionization enthalpies due to the shielding effect of the inner 4f electrons and their relatively large atomic size. IE values generally show a slight increase across the lanthanide series due to the lanthanide contraction, which causes a gradual decrease in atomic radii and a corresponding increase in effective nuclear charge.

Pauling Electronegativity: 1.23
Trend: Holmium is highly electropositive, characteristic of metals, especially those in the lanthanide series. Its electronegativity is low, indicating a strong tendency to lose electrons rather than gain them.

Value: Data not precisely reported for Holmium; however, for most metals, especially electropositive ones like lanthanides, the electron gain enthalpy is either slightly positive or close to zero, meaning they do not readily accept electrons.

Metallic Radius: 177 pm
Trend: As a lanthanide, Holmium exhibits lanthanide contraction. This phenomenon refers to the steady decrease in the atomic and ionic radii of the lanthanide elements with increasing atomic number, due to the poor shielding effect of the 4f electrons. Consequently, Holmium’s atomic radius is slightly smaller than expected if this contraction did not occur, and it is generally smaller than preceding lanthanides.

Holmium is a silvery-white, relatively soft, and malleable metal.