Yes, something can be made of only one type of atom. In fact, the vast majority of matter around us consists of single types of atoms or molecules composed of those atoms. These individual atoms can combine to form various substances and materials.
Atoms are the basic building blocks of matter and are composed of protons, neutrons, and electrons. Each element on the periodic table corresponds to a specific type of atom with a unique number of protons in its nucleus. For example, all atoms with six protons are carbon atoms, and all atoms with one proton are hydrogen atoms.
Elements can exist in different isotopes, which have the same number of protons but different numbers of neutrons. However, isotopes of the same element are still considered the same type of atom because they have the same chemical properties.
On the subatomic level, there are fundamental particles like electrons, protons, and neutrons. However, in everyday matter, these particles are typically combined in different configurations to form atoms. So, while matter can be made of different particles, atoms are the most common constituents, and they consist of only one type of atom.