The mass of one oxygen atom is calculated by dividing the atomic mass of oxygen by Avogadro's number.
Understanding the Calculation
Atomic Mass of Oxygen
The atomic mass of oxygen is approximately 16.00 grams per mole. This value represents the average mass of oxygen atoms, taking into account the different isotopes and their relative abundances.
Avogadro's Number
Avogadro's number is a fundamental constant in chemistry, representing the number of atoms or molecules in one mole of a substance. Its value is approximately $6.022 \times 10^{23}$.
Calculation Steps
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Start with the atomic mass of oxygen: 16.00 grams/mole.
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Divide by Avogadro's number:
Calculation Value Atomic mass of oxygen 16.00 grams/mole Avogadro's number $6.022 \times 10^{23}$ Mass of one oxygen atom (grams) $2.66 \times 10^{-23}$ This calculation gives you the mass of a single oxygen atom in grams.
Example
To find the mass of one oxygen atom:
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Divide the atomic mass of oxygen (16.00 g/mol) by Avogadro's number ($6.022 \times 10^{23}$).
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Mass of one oxygen atom = $\frac{16.00 \text{ g/mol}}{6.022 \times 10^{23} \text{ atoms/mol}} = 2.66 \times 10^{-23}$ grams
Practical Insights
- Units: It is essential to keep track of units during the calculation. The units of grams per mole (g/mol) for atomic mass and atoms per mole (atoms/mol) for Avogadro's number ensure that the final answer is in grams, representing the mass of a single atom.
- Approximation: The atomic mass used (16.00 g/mol) is an approximation. The precise atomic mass may vary slightly depending on the isotopic composition of the oxygen sample.
