Question

Are the elements lanthanum and actinium considered to be in the d block or the f block of the periodic table?

A) Both lanthanum and actinium are in the d block.

B) Both lanthanum and actinium are in the f block.

C) Lanthanum is in the d block, while actinium is in the f block.

D) Lanthanum is in the f block, while actinium is in the d block.

E) Neither lanthanum nor actinium is part of either the d block or the f block.

Answer 1

Lanthanum and actinium are transitional metals typically placed in the d block of the periodic table, but due to their chemical behavior, they are associated with the f block series, making the correct answer (C) Lanthanum is in the d block, while actinium is in the f block.

Step-by-step explanation:

The question concerns whether lanthanum and actinium are considered to be in the d block or the f block of the periodic table. Both of these elements are typically situated in the d block of the periodic table.

However, due to their chemical behavior and similarities to f block elements, lanthanum is often associated with the lanthanide series and actinium with the actinide series. Lanthanum and actinium, because of their similarities to the other members of the respective series, are included and used to name these series, even though they are transition metals with no f electrons.

To answer the question directly, the correct choice would be (C) Lanthanum is in the d block, while actinium is in the f block. This takes into account not only their position in the periodic table but also their chemical properties and similarities to other elements in the f block series.