Lecture Notes on Atoms and Ions

Key Concepts

• Atom: Consists of protons, neutrons, and electrons.
• Nucleus: Center of the atom containing protons and neutrons.
• Periodic Table: Tool for reading atomic structure, including atomic number and mass.

Atomic Number vs. Atomic Mass

• Atomic Number: Number of protons in an atom.
• Atomic Mass: Sum of protons and neutrons in an atom.

Isotopes

• Definition: Atoms of the same element with different numbers of neutrons.
• Examples:
  • Carbon Isotopes:
    • Carbon-12
    • Carbon-13 (extra neutron)
    • Carbon-14 (extra 2 neutrons)
• Characteristics: Isotopes have the same number of protons but vary in neutron count.

Practice Problem

• Nitrogen-16 (N-16) and Aluminum-27 (Al-27):
  • Count protons using the periodic table:
    • Nitrogen: 7 protons
    • Aluminum: 13 protons
  • Calculate neutrons:
    • N-16: 16 total - 7 protons = 9 neutrons
    • Al-27: 27 total - 13 protons = 14 neutrons

Neutral Atoms vs. Ions

• Neutral Atom: Protons equal electrons.
  • Example: Lithium with 3 protons and 3 electrons.
• Ions:
  • Occurs when protons do not equal electrons.
  • Types of Ions:
    • Cation: Positively charged ion (fewer electrons than protons).
      • Example: Subtracting electrons from lithium makes it a cation.
      • Remember: "Cats are positive."
    • Anion: Negatively charged ion (more electrons than protons).

Summary

• Change in Protons: Results in a different element.
• Change in Neutrons: Results in different isotopes.
• Change in Electrons: Results in ions (charged particles).

Additional Notes

• Ions: Can be atoms or molecules.
• Charged Particles: Ions can be positive or negative.

Use these notes to review the concepts of atomic structure, isotopes, and the formation of ions. Remember to refer to the periodic table for determining protons and apply simple subtraction to find the number of neutrons.