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Chapter 11
Introduction to Atoms
Term | Definition |
---|---|
Atom | The smallest unit of an element that maintains the properties of that element. |
Electron | A subatomic particle that has a negative charge. |
Nucleus | In physical science, an atom's central region, which is made up of protons and neutrons (the center of the atom). |
Electron cloud | A region around the nucleus of an atom where electrons are likely to be found (the area outside of the nucleus that contains electrons). |
Proton | A subatomic particle that has a positive charge and that is found in the nucleus of an atom. |
Atomic mass unit | A unit of mass that describes the mass of an atom or molecule. |
Neutron | A subatomic particle that has no charge (it's neutral) and is found in the nucleus of an atom. |
Atomic number | The number on the periodic table that tells an individual atom's number of protons. |
Isotope | An atom that has the same number of protons but a different number of neutrons. This means it has a different atomic mass from other atoms with the same number of protons. |
Mass number | The sum of the protons and neutrons in the atom. |
Atomic mass | The mass of an atom expressed in atomic mass units. (The weighted average of the masses of all the naturally occurring isotopes of that element). |