Crash Course Chemistry with Hank Green

Introduction to Chemistry

• Chemistry is the science of matter and the interactions of tiny particles: protons, neutrons, and electrons.
• It's a bridge between abstract particle physics and tangible biology.
• Chemistry explains life formation, cancer cures, technology, and environmental sustainability.

Key Concepts in Chemistry

• Atomic Theory: The idea that matter is made from atoms, tiny particles that form everything.
  • Initially a controversial theory, confirmed by Einstein in 1905.
  • Atoms' existence proved through Brownian motion.

Structure of Atoms

• Atoms consist of three subatomic particles:
  • Proton: Positively charged, heavy.
  • Neutron: No charge, similar mass to protons.
  • Electron: Negatively charged, negligible mass compared to protons/neutrons.
• Protons and neutrons form the nucleus; electrons orbit the nucleus.

Importance of the Nucleus

• The number of protons (atomic number) determines the element.
  • Example: 79 protons = gold, 47 protons = silver.
• Atomic number is a defining trait and remains stable; very difficult to change.
• Nuclei: Generally stable and boring as they change very little over time.

Isotopes and Atomic Mass

• Isotopes: Same element, different number of neutrons, same chemical properties.
  • Example: Silver has isotopes with mass numbers 107 and 109.
• Relative Atomic Mass: Average mass of all isotopes of an element on Earth.
• Mass number: Total number of protons and neutrons.

Chemistry Nomenclature

• Chemical symbols derived historically (e.g., silver is 'Ag' from 'argentum').
• Writing elements: Atomic number, mass number, and charge notation.

Conclusion

• Nucleus vs. Electrons:
  • Nucleus: Stable, few changes, where the atomic number is defined.
  • Electrons: Involved in chemical reactions and interactions.
• Understanding atoms equips one with knowledge not available in 1900.

Additional Resources

• Crash Course Chemistry team credits.
• Encouragement to engage with the material and ask questions.