The atomic mass of sodium is calculated by adding the number of protons and neutrons in its nucleus.
Understanding Atomic Mass
Atomic mass, sometimes called atomic weight, represents the total mass of protons and neutrons within an atom's nucleus. Electrons are very light and contribute negligibly to the overall mass. The atomic mass is typically expressed in atomic mass units (amu) or daltons (Da).
Sodium's Atomic Mass
Based on the provided reference:
- Sodium has an atomic number of 11, which means it has 11 protons.
- The number of neutrons in a common sodium isotope is 12.
- Therefore, sodium's atomic mass is calculated as: 11 (protons) + 12 (neutrons) = 23 amu.
Why is Atomic Mass Important?
Understanding the atomic mass of an element is essential for various reasons:
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Stoichiometry: Atomic mass is crucial in chemical calculations, allowing us to determine the mole concept.
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Molar Mass: Sodium has an atomic mass of 23 amu. In grams, this translates to 23 grams per mole (g/mol), which is its molar mass. A mole of any substance contains 6.022 × 1023 particles (Avogadro's number). Knowing this relationship enables the accurate conversion between mass and quantity of substances.
- For instance, 1 mole of sodium equals 23 grams.
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Predicting Properties: The atomic mass, in combination with the arrangement of electrons, determines the chemical properties of a substance.
Summary Table: Sodium
| Property | Value |
|---|---|
| Atomic Number | 11 |
| Number of Protons | 11 |
| Number of Neutrons | 12 |
| Atomic Mass | 23 |
| Molar Mass | 23 g/mol |
The atomic mass of sodium is 23 amu, which is numerically equal to the molar mass of sodium being 23 g/mol. This means that a mole of sodium weighs 23 grams.
