This phenomenon occurs cyclically.

This is my first question.

Rare earth elements are essential materials for the manufacture of electronic devices.

An isotope refers to elements with the same atomic number but different numbers of neutrons.

Transition elements play an important role in chemical reactions.

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

This cylindrical chart helps to visually understand the basic concepts of physics.

His ostensible attitude is hiding what he is really thinking.

He always tries to maintain the face of things.

That information is listed outside the table.