How were atomic models developed when no one has seen an atom?

Experiments

Explanation:

Models of the atom are developed by experiments in which evidences that support various models are obtained via ingenious means. For instance, in Rutherford's experiments, he made use of a thin gold foil. The foil contains gold atoms though they cannot be seen with naked eyes. The inferences deduced from the experiments can be generalized to all atoms since atoms of all elements posses essentially the same structure even though the energy levels are different for each atom.

the pseudoscience are like beliefs, theories, or like practices that are considered scientific