Looks like no one added any tags here yet for you.
Mass number
Total number of protons and neutrons in an atom.
Atomic number
The number of protons in an atom, found as the larger number on the periodic table.
Atomic mass
The average of the relative amounts of each isotope of an element.
Electrons
Negatively charged particles found outside of the nucleus of an atom.
Protons
Positively charged particles found in the nucleus of an atom.
Neutrons
Uncharged particles found in the nucleus of an atom.
Neutral atoms
Atoms that have the same number of electrons and protons.
Isotopes
Atoms of the same element with the same number of protons but a differing number of neutrons.
Ions
Atoms that have an unequal number of protons and electrons, resulting in a charge.
Positive ion
Formed when an atom has more protons than electrons.
Negative ion
Formed when an atom has more electrons than protons.
Fractional abundance
The percentage of a particular isotope in a total sample of atoms, expressed as a decimal.
Calculating average atomic mass (AAM) formula
(atomic mass of isotope #1) x (fractional abundance of isotope #1) + (atomic mass of isotope #2) x (fractional abundance of isotope #2).
Significant figures rule for multiplication/division
Round to the least number of significant figures in the calculation.
Significant figures rule for addition/subtraction
Align decimal points; round to the smallest number of decimal places.