Gadolinium (Gd) Revision Guide

Gadolinium (Gd) Atomic Model Details

Gadolinium (Gd) is a lanthanide element with atomic number 64. It is part of the f-block elements.

Atomic Number (Z): 64
Protons: 64
Electrons: 64 (in a neutral atom)
Neutrons: The most abundant isotope, ¹⁵⁸Gd (natural abundance ~24.8%), has 158 - 64 = 94 neutrons. The average number of neutrons based on the atomic mass of 157.25 u is approximately 93.
Atomic Mass: 157.25 u
Atomic Radius (Metallic): 179 pm (picometers)
Ionic Radius (Gd³⁺): 107.8 pm

Gadolinium exhibits an unusual electronic configuration due to the stability associated with half-filled (4f⁷) and completely filled (4f¹⁴) orbitals.

Electronic Configuration: [Xe] 4f⁷ 5d¹ 6s²
- The 5d¹ electron contributes to its metallic character and is characteristic of the initial filling of the f-block in the lanthanide series, where the 5d orbital is partially occupied before the 4f orbital is half-filled.
- The stability of the half-filled 4f⁷ configuration is a significant factor.
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): 25 electrons (4s² 4p⁶ 4d¹⁰ 4f⁷)
- O-Shell (n=5): 9 electrons (5s² 5p⁶ 5d¹)
- P-Shell (n=6): 2 electrons (6s²)
- Total Electrons: 2 + 8 + 18 + 25 + 9 + 2 = 64 electrons.

Being a lanthanide, Gadolinium exhibits trends influenced by its position in the periodic table and the lanthanide contraction.

Ionization Enthalpy:
- First Ionization Enthalpy (IE₁): 593.4 kJ/mol. This value is relatively low, reflecting its metallic nature and the ease with which the outermost 6s electrons are removed.
- Second Ionization Enthalpy (IE₂): 1170 kJ/mol.
- Third Ionization Enthalpy (IE₃): 1990 kJ/mol. The formation of Gd³⁺ is highly favorable due to the resulting stable half-filled 4f⁷ configuration.
- Trend: Generally, ionization enthalpies across the lanthanide series show a slight irregular increase due to the poor shielding of 4f electrons (lanthanide contraction), leading to an increased effective nuclear charge.
Electronegativity (Pauling Scale): 1.20. Gadolinium is an electropositive metal, indicating a low tendency to attract electrons.
Electron Gain Enthalpy: Generally positive or negligible for metals. Gadolinium, being an electropositive metal, has a very low tendency to gain electrons, thus its electron gain enthalpy is not significant and often considered positive or close to zero.
Atomic Radius: As mentioned, 179 pm (metallic). There is a general decrease in atomic radius across the lanthanide series (lanthanide contraction), but irregularities exist.

Gadolinium is a typical silvery-white metal with distinct physical characteristics.

Density: 7.90 g/cm³ (at 20°C)
State at Room Temperature: Solid
Color: Silvery-white
Melting Point: 1312 °C (1585 K)
Boiling Point: 3273 °C (3546 K)
Magnetic Properties: Gadolinium is notable for being ferromagnetic at room temperature, a rare property among elements. Its Curie temperature is around 292 K (19 °C).