Alkali metals are very reactive chemically.

This rock is radioactive, so care must be taken when handling it.

Francium is a radioactive alkali metal that is hardly present in nature.

His existence enriches my life.

You can feel his presence.

In this chemical reaction, alkali is needed.

Alkaline earth metals are located in Group 2 of the periodic table.

This metal is very hard.

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Radioactive elements are produced in nature and scientific experiments.