This is my first question.

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

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

Transition elements play an important role in chemical reactions.

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

As if symbolizing the heat of summer, the cicadas started to sing.

I am working using a spreadsheet software.

This ancient document contains many characters not found in the standard character set.

He made an announcement about the new project at the meeting.

Please look at this parts list.