Who was the first person to come up with the idea of the "atom?"

Democritus

Explanation:

Democritus first introduced the idea of the atom almost 2500 years ago. Democritus was an important philosopher however if your talking about how the atom is today look at first rudimentary   pudding model by JJ Thomson first design then its Neils  Bohr whos model we look at today

b. accuracy of the data matters alot more than its number of digits, organization or amount of detail. quantitative observation is more accepted than the qualitative observation.