posted by sam .
Are these correct for Democritius
Help so confused - I read site and still trying to figure out.
atoms of same element are exactly alike
an atom is mostly empty space with a dense - postiveily chareged nucleus
These are the choices
Democritus was the first to come up with the idea that all elements were composed of atoms (about 400 BC). No one paid any attention to this idea and it was based on philosophical speculation and not experimention. In the late 1700s, scientists began to realize that the concept of atoms provided an explanation for many experimental observations about the nature of matter. By the early 1800s the Law of Conservation of Matter and the Law of Definite Proportions were accepted. John Dalton then put all of this together, with his four point that
1.elements are composed of extremely small particles called atoms.
2.All atoms of a given element are identical and atoms of different elemnts are different.
3.Atoms are not created nor destroyed.
4.Compounds are formed by atoms combining in definite ratios (small whole numbers).
Rutherford advanced the idea that atoms consist of a core (nucleus) that carried a positive charge with the electrons outside the nucleus. The atoms was mostly empty space. Bohr added the idea that the electrons were in definite orbits about the nucleus and that each orbit had a particular energy level.