CHEM 1151 Lecture Notes - Lecture 5: Weighted Arithmetic Mean, Unified Atomic Mass Unit
Document Summary
For a neutral atom, it will also be the number of electrons. It is always a whole number: mass number, mn: the number of protons plus the number of neutrons. The mass number determines the type of isotope. Isotopes: two atoms of the same element with different numbers of neutrons (different mass numbers) Ions: an atom or group of atoms that has a net charge, or a different number of protons and electrons. It is not the same thing as the mass number. Calculating the atomic weight: (%/100) x (mass number) for each isotope. Round the mass number to 2 places past the decimal.
