Lecture on Ionic Bonds

Presented by Michele Glass

• Topic: Ionic Bond
• Previous Topic: Chemical behavior of an atom

Key Concepts

Chemical Bond Reactivity

• Atoms with incomplete valence shells or unpaired electrons are reactive.
• Reactive atoms can form chemical bonds:
  • Ionic Bonds (current topic)
  • Covalent Bonds (next lecture)

Definition of Ions

• Ions: Charged atoms
• Types of Ions:
  • Cations: Positively charged ions (loss of electrons)
    • Memory aid: 't' in cation looks like a '+'.
  • Anions: Negatively charged ions (gain of electrons)

Formation of Ions

• Electrons: Only subatomic particles exchanged in ion formation.
• Changing protons changes the element.

Ionic Bond Formation

• Memory device: "transfer of electrons"
• One atom loses electrons (becomes cation), and the other gains electrons (becomes anion).
• Key Feature: Attraction between opposite charges (cation and anion).

Example: Sodium and Chlorine

• Sodium (Na)

  • Atomic Number: 11
  • Protons: 11
  • Neutrons: 11
  • Electrons: 11 (2 in the first shell, 8 in the second, 1 in the valence shell)
  • Loses 1 electron becoming a cation (Na+)

• Chlorine (Cl)

  • Atomic Number: 17
  • Protons: 17
  • Neutrons: 17
  • Electrons: 17 (fills valence shell to become stable)
  • Gains 1 electron becoming an anion (Cl-)

• Sodium Chloride (NaCl)

  • Formation: Na+ donates an electron to Cl-
  • Notation: Na+Cl-
  • Naming: Anions get "-ide" endings — Chlorine becomes Chloride

Ionic Bond Characteristics

• Fully charged atoms
• Cation listed first in chemical formula, anion second.
• Held together by electrostatic attraction.

Additional Resources

• Comics and mnemonic devices to aid memory.

Next Steps

• Stay tuned for the next lecture on Covalent Bonds.
• Reminder to take care of yourselves and each other.