Elements that are made in particle accelerators and not found in nature are called transuranic elements.

Here's why:

* Transuranic means "beyond uranium". Uranium is the heaviest naturally occurring element (atomic number 92).

* Particle accelerators are machines that accelerate charged particles to extremely high speeds and energies. By smashing these particles together, scientists can create new elements.

These elements are unstable and tend to decay radioactively, which is why they aren't found naturally on Earth. However, they are important for scientific research and have applications in medicine and other fields.