4.2 The Atom Flashcards
a subatomic particle that has a positive charge and that is found in the nucleus of an atom
protons
a unit of mass that describes the mass of an atom or molecule
atomic mass unit
a subatomic particle that has no charge and that is found in the nucleus of an atom
neutron
the number of protons in the nucleus of an atom; the atomic number is the same for all atoms of an element
atomic number
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)
isotope
the sum of the numbers of protons and neutrons in the nucleus of an atom
mass number
the mass of an atom expressed in atomic mass units
atomic mass