Atom
noun
The original child of everything is the atom. It is the child from which everything else is created, for it was the original child. Atoms are the building blocks of all things!
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
しょう来は、原子エネルギーの勉強をしたいと思っています。
In the future, I think I want to study atomic energy.
この原子の原子番号と原子記号は何だったっけ?
What was the atomic number and atomic symbol of this atom?
老朽化した原子力発電所は、多くの国々にとって悩みの種です。
Aging nuclear power plants are a problem for many countries.