d and f BLOCK ELEMENTS

What is the main factor causing the actinoid contraction?

• Loss of electrons
• Increase in nuclear charge with poor 5f electron shielding
• Decrease in proton number
• Expansion of electron clouds

What type of reaction occurs when actinoids combine with most non-metals?

• Displacement
• Combination
• Precipitation
• Neutralization

Which property of actinoids is NOT described as being similar to lanthanoids, even in the early part of the series?

• Reactivity with non-metals
• Magnetic properties
• Gradual variation in properties
• Similarities among members

What is the primary reason for the lower ionization enthalpies in early actinoids compared to early lanthanoids?

• Smaller atomic size
• Greater shielding of 5f electrons
• Fewer protons in the nucleus
• Higher electronegativity

Why is actinoid contraction greater than lanthanoid contraction from element to element?

• Because 5f electrons provide better shielding than 4f electrons.
• Because 5f electrons provide poorer shielding than 4f electrons.
• Because actinoids have more protons.
• Because actinoids are heavier.