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Chemistry Vocab 4
Term | Definition |
---|---|
Atom | The smallest particle of an element that retains its identity in a chemical reaction. |
Dalton's Atomic Theory | The first theory to relate chemical changes to events at the atomic level. |
Electron | A negatively charged subatomic particle. |
Cathode Ray | A stream of electrons produced at the negative electrod (cathode) of a tube containing a gas at low pressure. |
Proton | A positively charged subatomic particle found in the nucleus of an atom. |
Neutron | A subatomic particle with no charge and a mass of 1 am; found in the nucleus of an atom. |
Nucleus | The tiny, dense central portion of an atom, composed of protons and neutrons. |
Atomic Number | The number of protons in the nucleus of an atom of an element. |
Mass Number | The total number of protons and neutrons in the nucleus of an atom. |
Isotope | Atoms of the same element that have the same atomic number but different atomic masses due to a different number of neutrons. |
Atomic Mass Unit (AMU) | A unit of mass equal to 1/2 the mass of a carbon-12 atom. |
Atomic Mass | The weighted average of the masses of the isotopes of an element. |