It's not quite that simple! While we can say that atoms are the fundamental building blocks of everything we know, there's not just *one* type of atom that makes up everything. There are actually many different types of atoms, called elements.

Here's why:

* Different elements have different properties: Each element is made up of atoms with a unique number of protons in their nucleus. This number, called the atomic number, determines the element's chemical behavior.

* Complexity in the universe: From the simplest hydrogen atom to the complex molecules in your body, everything is built from combinations of different elements. For example, water is made of hydrogen and oxygen, while your body is made up of elements like carbon, hydrogen, oxygen, nitrogen, and many more.

So, instead of one fundamental atom, think of the periodic table as a collection of all the fundamental building blocks that make up everything in the universe. Each element on the periodic table is a different type of atom with unique properties.