On the periodic table, where are the majority of radioactive elements located?

• A. In the first two columns, among the alkali and alkaline earth metals
• B. In the center block, among the transition metals
• C. In the upper right corner, among the noble gases
• D. In the bottom rows, particularly among the actinides and some lanthanides

Answer: (D)

Verified step by step guidance

1. Understand that radioactive elements are those that exhibit radioactivity due to unstable nuclei, which often occurs in heavy elements with large atomic numbers.
2. Recall the layout of the periodic table: the main groups (alkali metals, alkaline earth metals, transition metals, noble gases) are arranged in columns, while the lanthanides and actinides are placed separately at the bottom.
3. Recognize that the majority of naturally radioactive elements are found in the bottom two rows of the periodic table, known as the lanthanide and actinide series.
4. Note that the actinides, in particular, contain many radioactive elements such as uranium and thorium, which are well-known for their radioactivity.
5. Conclude that the correct location for the majority of radioactive elements is in the bottom rows of the periodic table, especially among the actinides and some lanthanides.