Avogadro's number

(noun)

The number of atoms present in 12 g of carbon-12, which is $6.022\times10^{23}$ and the number of elementary entities (atoms or molecules) comprising one mole of a given substance.

Related Terms

Examples of Avogadro's number in the following topics:

  • Avogadro's Number and the Mole

    • The mole is represented by Avogadro's number, which is 6.02×1023 mol-1.
    • Avogadro's number is a proportion that relates molar mass on an atomic scale to physical mass on a human scale.
    • Avogadro's number is defined as the number of elementary particles (molecules, atoms, compounds, etc.) per mole of a substance.
    • Avogadro's number is a similar concept to that of a dozen or a gross.
    • Avogadro's number is 6.022×1023 molecules.

  • Converting between Moles and Atoms

    • By understanding the relationship between moles and Avogadro's number, scientists can convert between number of moles and number of atoms.
    • The bridge between atoms and moles is Avogadro's number, 6.022×1023.
    • This form shows the role of Avogadro's number as a conversion factor between the number of entities and the number of moles.
    • Given a known number of moles (x), one can find the number of atoms (y) in this molar quantity by multiplying it by Avogadro's number:
    • This can be written without a fraction in the denominator by multiplying the number of atoms by the reciprocal of Avogadro's number:

  • Avogadro's Law: Volume and Amount

    • Avogadro's Law states that at the same temperature and pressure, equal volumes of different gases contain an equal number of particles.
    • Avogadro's Law (sometimes referred to as Avogadro's hypothesis or Avogadro's principle) is a gas law; it states that under the same pressure and temperature conditions, equal volumes of all gases contain the same number of molecules.
    • The law is named after Amedeo Avogadro who, in 1811, hypothesized that two given samples of an ideal gas—of the same volume and at the same temperature and pressure—contain the same number of molecules; thus, the number of molecules or atoms in a specific volume of ideal gas is independent of their size or the molar mass of the gas.
    • By Avogadro's Law, this meant that hydrogen and oxygen were combining in a 2:1 ratio.
    • Using Avogadro's Law, this experiment confirmed that 2 hydrogen and 1 oxygen form 1 water molecule.

  • The Effect of the Finite Volume

    • where NA is Avogadro's number and r is the radius of the molecule.

  • Converting between Mass and Number of Moles

    • One mole (abbreviated mol) is equal to 6.022×1023 molecular entities (Avogadro's number), and each element has a different molar mass depending on the weight of 6.022×1023 of its atoms (1 mole).
    • By recognizing the relationship between the molar mass (g/mol), moles (mol), and particles, scientists can use dimensional analysis convert between mass, number of moles and number of atoms very easily.
    • To determine the number of atoms, convert the moles of Ni to atoms using Avogadro's number:
    • Given a sample's mass and number of moles in that sample, it is also possible to calculate the sample's molecular mass by dividing the mass by the number of moles to calculate g/mol.
    • Convert between the mass and the number of moles, and the number of atoms, in a given sample of compound

  • Scientific Notation

    • Scientific notation is a more convenient way of writing very small or very large numbers.
    • To express a number in scientific notation, you move the decimal place to the right if the number is less than zero or to the left if the number is greater than zero.For example, in 456000, the decimal is after the last zero, so to express this in scientific notation, you would need to move the decimal to in between the 4 and 5.
    • The number of times you move the decimal place becomes the integer "b."
    • Therefore, our number in scientific notation would be: $4.56 \times 10^5$.
    • Learn to convert numbers into and out of scientific notation.

  • Molar Mass of Compounds

    • Chemists can measure a quantity of matter using mass, but in chemical reactions it is often important to consider the number of atoms of each element present in each sample.
    • One mole (abbreviated mol) is equal to the number of atoms in 12 grams of carbon-12; this number is referred to as Avogadro's number and has been measured as approximately 6.022 x 1023.

  • Molar Mass of Gas

    • The molar mass of a particular gas is therefore equal to the mass of a single particle of that gas multiplied by Avogadro's number (6.02 x 1023 ).

  • Converting from One Unit to Another

    • Algebraically, we know that any number multiplied by one will be unchanged.
    • If, however, the number has units, and we multiply it by a ratio containing units, the units in the number will multiply and divide by the units of the ratio, giving the original number (remember you are multiplying by one) but with different units.
    • The given number is a numerical quantity (with its units).
    • For example, say you were trying to convert 3.41 grams of He to a number of atoms of He.
    • Avogadro's number, 6.022 x 1023 atoms = 1 mole, will also help you in this problem.

  • Lattice Energy

    • In this equation, NA is Avogadro's constant; M is the Madelung constant, which depends on the crystal geometry; z+ is the charge number of the cation; z- is the charge number of the anion; e is the elementary charge of the electron; n is the Born exponent, a characteristic of the compressibility of the solid; $\epsilon _o$ is the permittivity of free space; and r0 is the distance to the closest ion.