The model of the atom has changed over time in light of new knowledge and discoveries. Which option correctly describes one such change? a. In 420 B. C., John Dalton developed the idea that small atoms combined to form molecules.

b. About 1900, Neils Bohr developed an atomic model where positively charged particles orbit a negatively charged nucleus.

c. About 1900, J. J. Thomson discovered electrons were negatively charged particles.

d. About 1915, J. J. Thomson developed an atomic model where negatively charged particles orbit a positively charged nucleus.