Chemistry Lecture: Understanding the Atom

Overview

• Review of atomic structure and isotopes
• Electron energy levels and movements

Atomic Structure

• Nucleus: Center of the atom containing:
  • Protons: Positively charged (+1), relative mass of 1
  • Neutrons: Neutral charge, relative mass of 1
• Electrons: Orbit nucleus in shells, negatively charged (-1), approximately 2000 times smaller than protons/neutrons

Periodic Table and Elemental Information

• Nucleus Symbol: Each box represents a specific element
• Elemental Symbol (e.g., Li for Lithium): Located in the box
• Atomic Number (bottom left of box): Indicates number of protons, defines the element
  • Example: Lithium has 3 protons
• Mass Number (top left of box): Total number of protons and neutrons
  • Example: Lithium's mass number is 7 (3 protons + 4 neutrons)
• Electron Count: Equals number of protons in a neutral atom

Isotopes

• Atoms with the same number of protons but different numbers of neutrons
• Examples of Lithium:
  • Lithium-7: 3 protons, 4 neutrons
  • Lithium-6: 3 protons, 3 neutrons
  • Lithium-8: 3 protons, 5 neutrons
• Stability: Generally, only 1 or 2 isotopes are stable
• Radioactive Decay: Unstable isotopes emit radiation (alpha, beta, gamma) or neutrons

Electron Energy Levels

• Electrons arranged in shells, each with increasing energy levels further from the nucleus
• Excited Electrons:
  • Can jump to a higher energy level when absorbing electromagnetic radiation
  • Returns to a lower energy level, re-emitting energy as electromagnetic radiation

Ionization

• Outer electrons can absorb energy and leave the atom, leading to ionization
• Results in a positive ion (more protons than electrons)
• Ionizing Radiation: Radiation that can knock electrons off atoms, causing ionization

Conclusion

• Summary of atomic structure, isotopes, and electron behavior
• Encouragement to like and subscribe for more content