Final answer:
One mole of any substance contains 6.022\u00d71023 atoms, molecules, or formula units, known as Avogadro's number. Knowing the molecular formula is essential for determining the number of specific atoms in a mole of molecules. The molar mass is used to convert between the mass of a substance and the number of moles.
Step-by-step explanation:
Understanding the Mole Concept in Chemistry
One mole of a substance contains 6.022\u00d71023 atoms, molecules, or formula units. This number is known as Avogadro's number, and it applies regardless of the substance being an element or a compound. Therefore, there are exactly 6.022\u00d71023 atoms in 1 mole of an element, 6.022\u00d71023 molecules in 1 mole of a molecular compound, and 6.022\u00d71023 formula units in 1 mole of an ionic compound.
For instance, to calculate the number of moles of a specific atom within a molecule, the molecular formula of the substance must be known. Considering 5.6\u00d71022 molecules of MgF2, one molecule of magnesium fluoride (MgF2) contains 1 atom of magnesium (Mg) and 2 atoms of fluorine (F). Hence, the total number of atoms of fluorine in 5.6\u00d71022 molecules of MgF2 would be twice the number of molecules, which is 1.12\u00d71023 atoms of fluorine.
In stoichiometric calculations, knowing molar mass is crucial as it links the mass of a substance (that can be measured on an analytical balance) to the amount of substance in moles. By using the formula of a compound and its molar mass, we can convert between grams and moles, and through Avogadro's number, relate moles to the number of atoms or molecules.