d and f BLOCK ELEMENTS

Why is the term 'lanthanoid contraction' used instead of simply 'atomic size decrease'?

• Because it specifically refers to the cumulative effect across the entire Lanthanoid series
• Because it sounds more scientific
• Because it only applies to ionic radii
• Because it was named after Lanthanum

What is the main implication of the lanthanoid contraction for the chemistry of elements following the Lanthanoid series?

• It causes elements in the sixth period to have properties similar to those in the fifth period
• It makes all elements radioactive
• It eliminates the difference between metals and non-metals
• It makes sixth-period elements less reactive

Which of the following best describes the trend in ionic radii for the entire series of Lanthanoid M³⁺ ions?

• A fairly regular decrease from La³⁺ to Lu³⁺
• A fairly regular increase from La³⁺ to Lu³⁺
• No significant change across the series
• An irregular zig-zag pattern

Based on the general trend 4fⁿ for Ln³⁺ ions, what would be the expected electronic configuration for the tripositive ion of Cerium (Ce)?

• 4f¹
• 4f⁰
• 4f²
• 5d¹

Based on the general trend 4fⁿ for Ln³⁺ ions, what would be the expected electronic configuration for the tripositive ion of Praseodymium (Pr)?

• 4f²
• 4f³
• 4f¹
• 4f⁴