Dalton proposed that each chemical element is composed of atoms of a single, unique type, and though they cannot be altered or destroyed by chemical means, they can combine to form more complex structures chemical compounds.
A theory that can be too easily adapted to any new evidence has no real scientific value. Were they the smallest particles, or was there something smaller? In fact, some reflected completely backwards and were detected next to the gun from which they were first produced.
Given that all theories are tentative, and may be revised or abandoned, perhaps it is wise not to use scientific ideas to decide what is good or bad, in any moral sense.
This will work anywhere in the solar system. The latter point is one that pretty much still holds true, with the notable exception being isotopes of different elements, which differ in their number of neutrons.
Each electron is equally present in both orbital zones, shown here by color only to highlight the different wave phase. Compounds are a combinations of elements. Among the early experimentalists was Robert Boyle —who studied quantitatively the compression and expansion of air, which led him to the idea that air was composed of particles that he called corpuscleswhich he maintained were in constant motion.
The result, he said, was something like shooting a cannon ball at a piece of tissue paper and having the ball bounce back at you. The purpose of these exercises is to set up the lesson and establish students' level of awareness regarding the basic concepts and the critical early figures that first developed them.
At any rate, the atom gives us a great example of how scientific models can change over time, and shows how new evidence can lead to new models. Explanations that invoke the supernatural or the totally subjective are by definition not scientific, because there is no imaginable experiment that could be done that might provide evidence one way or another for their validity.