ACS Organic Chemistry Practice Test

Avogadro's number defines how many elementary entities are in one mole of any substance. It is the fixed count that lets you convert between amount in moles and the actual number of particles: N = n × N_A. The value is 6.022×10^23 particles per mole, and it is universal for atoms, molecules, ions, and other small units. It is not the number of moles in a mole (that would be 1), nor the mass of a single particle in grams (that mass comes from the molar mass divided by N_A), nor the volume per mole at STP (that volume is about 22.4 L for an ideal gas, not a count of particles).