Who first used the word "atomos" to describe the smallest unit of a substance? thomson democritus bohr schrödinger?

The correct answer is Democritus.

Explanation:

Democritus was a Greek philosopher and is still remembered for his contribution towards the atomic structure of the universe. He first described the smallest unit of a substance and named it as "atomos".

Thomson gave plum pudding model describing that electrons are surrounded by a soup of positive charge and to balance this positive charge,  negatively charged electrons are present, as there are plums in pudding.

Bohr gave the planetary motion of an atom where electrons are the planets that revolve around the nucleus considered as Sun.

Schrodinger gave the quantum mechanical model of an atom.

Hence, the correct answer is Democritus.

first one is the correct answer