Final answer:
Atoms were not able to be seen until the 1800s using microscopes.
Step-by-step explanation:
In the 1800s, advancements in microscopy technology allowed scientists to finally see atoms. Prior to this, the existence of atoms was supported by indirect evidence and theories proposed by ancient philosophers like the Greeks. However, it wasn't until the early 20th century that scientists were able to directly observe atoms using more advanced microscopes.