Structure of an atom

• What are the three subatomic particles in an atom?

  Protons, neutrons, and electrons.
• What is the atomic number of an atom?

  The number of protons in an atom. It determines the element.
• What is the mass number of an atom?

  The total number of protons and neutrons in an atom.
• Where are protons, neutrons, and electrons found in an atom?

  • Protons and neutrons are in the nucleus.
  • Electrons orbit the nucleus in energy levels (shells).