Carbon-13 has an atomic mass of 13 amu. Atomic weight, unlike the weight of an object, has nothing to do with the pull of gravity. It is a unitless value that is a ratio of the atomic masses of Atomic mass is the mass of an individual atom, whereas atomic weight is the average (weighted) of the atomic masses of an atom's naturally occurring isotopes. Click the card to flip 👆 1 / 56 Hydrogen Atomic number = 1 Atomic mass = 1 # of Protons = 1 # of Neutrons = 0 Deuterium (Hydrogen Isotope) Atomic number = 1 Atomic MASS = 2 # of Protons = 1 # of NEUTRONS = 1 REMEMBER The Atomic Number DOES NOT CHANGE The # of PROTONS DOES NOT CHANGE The ATOMIC MASS and the # of NEUTRONS DOES CHANGE!!! 2 days ago · Hint: Atomic mass of any element is the number of protons and neutrons in that atom. Atomic mass is measured and expressed in atomic mass units, amu. While, the expression of this mass in grams is called gram atomic mass. Gram atomic mass of an atom is equal to Avogadro number, $6.022\times {{10}^{23}}$ of atoms. 1 amu = $1.66\times {{10}^{-24}}g$. Aluminum (Al) - Relative atomic mass (A) of aluminum is 27. Aluminum is a soft, silvery-white, ductile metal in the boron group. Learn more about properties, density and melting point of aluminium along with atomic mass of aluminium. The relative atomic mass is the same as the molar mass (except molar mass is in g/mol). The molar mass of sodium is 22.99 g/mol. Now, you know the atomic number of sodium is 11, so you may wonder why the molar mass is not exactly 22 (11 protons and 11 neutrons). Finding molar mass starts with units of grams per mole (g/mol). When calculating molecular weight of a chemical compound, it tells us how many grams are in one mole of that substance. The formula weight is simply the weight in atomic mass units of all the atoms in a given formula. If the formula used in calculating molar mass is the molecular Atomic Weight (uncertainty) [u] Reference. Year. 2009 . Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA) 7 Information Sources. The mass number (symbol A, from the German word Atomgewicht [atomic weight]),1 also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is a mass and has units. The answers discuss this in detail, and discuss binding energy and how the carbon 12 isotope gets defined as having an integer mass. But all other atomic masses are not integers, they have mass units and weighted atomic weight averages have nothing to do with mass numbers. $\endgroup$ – 76ertC.