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2.3 Atomic Number and Mass Number

Part of Atomic Structure in Chemistry: Basic. Read the opening section, then create a free account for the full interactive lesson, practice, and progress tracking.

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What Is the Atomic Number?

The atomic number of an atom is the number of protons it has in its nucleus. This number is unique for each element and defines the element's identity. For example, hydrogen has an atomic number of 1 because it has one proton, while carbon has an atomic number of 6 because it has six protons. The atomic number also determines an atom's position on the periodic table, making it an essential property in chemistry.

In this unit

8 lessons

  1. 2.1Introduction to AtomsPreview lesson
  2. 2.2Subatomic ParticlesPreview lesson
  3. 2.3Atomic Number and Mass NumberThis lesson
  4. 2.4IsotopesPreview lesson
  5. 2.5Overview of the Periodic TablePreview lesson
  6. 2.6Introduction to Electron ArrangementPreview lesson
  7. 2.7Atomic Structure Diagrams & The Bohr ModelPreview lesson
  8. 2.8Ions and ChargesPreview lesson

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