Effects of Lanthanoid Contraction

The lanthanoid contraction has several important consequences:

• Similarities in Chemistry: The post-lanthanoid elements (like Hafnium) have similar atomic and ionic sizes to their 3d and 4d counterparts (like Zirconium), leading to similarities in their chemical properties.
• Separation Difficulty: The lanthanoids show very little variation in their chemical properties and ionic radii, making their separation from one another quite challenging.
• Increased Density: The decrease in size without a substantial decrease in mass results in higher densities for the elements that follow the lanthanoids.