Radioactive elements are produced in nature and scientific experiments.

The atomic number of helium is 2.

Oxygen, which is one of the chemical elements, is necessary for us to breathe.

Database transactions need to ensure their atomicity.

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

The room is hot, so please turn on the AC.

Actinium is a radioactive chemical element with the symbol Ac and atomic number 89.

Hydrogen is the most abundant element in the universe.

Education about sex is very important.

He is majoring in chemistry at university.