law of conservation of mass
- the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes
law of definite proportions
the law that states that a chemical compound always contains the same elements in exactly the same proportions by weight or mass.
law of multiple proportions
the law that states that when two elements combine to form two or more compounds, the mass of one element that combines with a given mass of the other is in the ratio of small whole numbers
the interaction that binds protons and neutrons, protons and protons, and neutrons and neutrons together in a nucleus.
the number of protons in the nucleus of an atom; the atomic number is the same for all atoms
an atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and thus a different atomic mass)
atomic mass unit
a unit of mass that describes the mass of an atom or molecule; it is exactly 1/12 of the mass of carbon atom with mass number 12 (abbreviation, amu)
average atomic mass
the weighted average of the masses of all naturally occurring isotopes on an element
the SI base unit used to measure the amount of a substance whose number of particles is the same as the number of atoms of carbon in exactly 12 g of carbon-12