4.2 The Atom Flashcards
1
Q
proton
A
a subatomic particle that has a positive charge and that is found in the nucleus of an atom
2
Q
atomic mass unit
A
a unit of mass that describes the mass of an atom or molecule
3
Q
neutron
A
a subatomic particle that has no charge and that is found in the nucleus of an atom
4
Q
atomic number
A
the number of protons in the nucleus of an atom; the atomic number is the same for all atoms of an element
5
Q
isotope
A
a number 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)
6
Q
mass number
A
the sum of the numbers of protons and neutrons in the nucleus of an atom
7
Q
atomic mass
A
the mass of an atom expressed in atomic mass units
