The Jin dynasty played an important role in Chinese history.

He likes to save money.

Transition metals play an important role in chemical reactions.

When he opened the door, a metallic sound echoed.

Alkali metals are very reactive chemically.

I learned about valence in chemistry class.

The atomic number of helium is 2.

Database transactions need to ensure their atomicity.

We must not forget the horror of the atomic bomb.

He measures time accurately using an atomic clock.