Final answer:
One mole of a substance contains exactly 6.022×1023 atoms, molecules, or formula units, known as Avogadro's number. This number allows for measurable quantities in grams to be converted to a count of particles, simplifying chemical calculations.
Step-by-step explanation:
What is Notable About the Number of Atoms in One Mole?
When we consider one mole of any substance, we are talking about 6.022×1023 atoms, molecules, or formula units, regardless of the substance. This number is known as Avogadro's number, and it represents a fixed quantity of particles, just like the word 'dozen' represents a fixed quantity of twelve. The concept of the mole is vital in chemistry because it allows us to convert between atoms, molecules, or formula units and measurable quantities in grams, using the molar mass of the substance.
The mole was chosen as a unit because the mass of individual atoms and molecules is incredibly small and inconvenient for practical measurements and chemical reactions. By using molar mass, chemists can relate the mass of a substance to the number of moles and thus to Avogadro's number of particles, greatly simplifying quantitative work in the laboratory.
Example of a Mole in Chemical Formulas
For instance, in 1 mole of water (H2O), there will be exactly 6.022×1023 molecules of water. If we were to break down these molecules into individual atoms, we would have twice as many hydrogen atoms as this number, and the same number of oxygen atoms, because of the 2:1 ratio in the chemical formula for water.