d and f BLOCK ELEMENTS

What is a characteristic shared by both early actinoids and lanthanoids?

• Having identical atomic radii.
• Showing large differences in chemical properties.
• Showing close similarities with each other and gradual property variation.
• Exhibiting only +3 oxidation state.

When do actinoids start to exhibit behavior similar to lanthanoids?

• From the very first element.
• In the first quarter of the series.
• In the second half of the actinoid series.
• Only in the last element.

What is a consequence of the outer electrons being less firmly held in actinoids?

• They are less reactive.
• They are more stable.
• They are less available for bonding.
• They are more available for bonding.

Why are the 5f electrons in actinoids more effectively shielded than 4f electrons in lanthanoids?

• Because 5f orbitals are larger.
• Because 5f orbitals penetrate less into the inner core.
• Because 5f electrons are farther from the nucleus.
• Because 5f electrons are lighter.

Based on the information about ionization enthalpies, how are the outer electrons held in early actinoids compared to early lanthanoids?

• More firmly
• Equally firmly
• Less firmly
• Sometimes more, sometimes less firmly