AFOQT Practice Test

What do the elements below the main periodic table represent?

1. Alkaline metals

2. Lanthanides and actinides

3. Noble gases

4. Metalloids

The correct answer is: Lanthanides and actinides

The elements located below the main body of the periodic table represent the lanthanides and actinides, which are two series of elements that belong to the f-block of the periodic table. This grouping distinguishes them from the s-block, p-block, and d-block elements that are presented in the main section of the table. The lanthanides consist of the 15 elements from lanthanum (atomic number 57) to lutetium (atomic number 71). They are known for their similar properties and are often characterized by their high magnetic susceptibility and their use in electronics and materials science. The actinides, starting from actinium (atomic number 89) to lawrencium (atomic number 103), include well-known elements such as uranium and plutonium. These elements are primarily recognized for their applications in nuclear energy and weaponry, as well as their radioactive properties. Understanding the positioning of these elements in the periodic table is important because it reflects their electronic configuration, which influences their chemical behavior and physical properties.