where R is the ideal gas constant, about 8.31446 J⋅K ⋅mol (which is the product of the Boltzmann constant k B and the Avogadro constant). And, indeed, the experimental values of c V,m for the noble gases helium, neon, argon, krypton, and xenon (at 1 atm and 25 °C) are all 12.5 J⋅K ⋅mol, which is ⁠ 3 / 2 ⁠ R ; even though their atomic weights range from 4 to 131.