Question

What is the "modern" definition of atomic theory?

Answer 1

Answer: The modern atomic theory states that atoms of one element are the same, while atoms of different elements are different. Each element has its own characteristic atomic number. Atoms of the same element can have different numbers of neutrons, however.

Explanation: N/A

Answer 2

the atomic theory states that all matter is composed of atoms.
Atoms themselves are composed of protons, neutrons, and electrons. Each element has its own atomic number, which is equal to the number of protons in its nucleus.