Anatomy & Physiology - Chapter 2 | 93 Questions with 100 % correct Answers | Verified

elements - substance composed of only one type of atom that cannot be broken into simpler constituents by chemical means compounds - chemical combination of two or more elements atoms - smallest particle of a chemical element that retains the properties of that element; particles that combine to form molecules subatomic particles - particles that make up atoms; neutrons, protons, electrons nucleus - dense, central core of an atom protons - positively charged subatomic particle neutrons - neutral subatomic particle electrons - small, negatively charged subatomic particle atomic number - number of protons in an atom of an element mass number (atomic mass) - number of protons plus the number of neutrons in an atom of an element energy level - limited region surrounding the nucleus of an atom at a certain distance containing electrons; shell