Why did the model of the atom change? A. New materials became available to build better models.
B. The structure of atoms changed over time.
C. Scientists did not like the original model.
D. Experiments provided new evidence about the atom.

A.

Los modelos atómicos cambian de acuerdo a nuevas investigaciones y nuevos descubrimientos, que nos ayudan a acercarnos a la forma real de un átomo y como este está compuesto.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.