Crash Course Chemistry with Hank Green

Introduction

• Objective: To convince the audience that chemistry is fascinating and enjoyable.
• Understanding the world through chemistry enhances the ability to enjoy and interact with it.
• Chemistry helps explain the formation of life, medical advancements, technology, and sustainability.
• Chemistry deals with the interactions of subatomic particles: protons, neutrons, and electrons.

The Basics of Chemistry

Atomic Theory

• Matter is made up of atoms, which was a revolutionary idea when first proposed.
• Scientific Theory: A well-tested set of ideas that explains many observations.
• Einstein's contribution in 1905 mathematically proved the existence of atoms and molecules via Brownian motion, settled the debate.
• Brownian motion: The random movement of particles, explained by collisions with smaller atomic particles.

Composition of Atoms

• Atoms are made up of three subatomic particles:
  • Proton: Positively charged, heavy, defines the element.
  • Neutron: Neutral charge, about the same mass as a proton, stabilizes the nucleus.
  • Electron: Negatively charged, very light, involved in chemical reactions.

The Nucleus

• Composed of protons and neutrons.
• The atomic number is the number of protons and defines the element (e.g., Silver: 47 protons).
• The chemical symbol might not match the English name due to historical reasons (e.g., Silver - Ag from Latin 'argentum').
• Nuclei are stable and define the element, though they can change in mass if neutrons vary.

Isotopes and Atomic Mass

• Isotopes: Variants of an element with different numbers of neutrons but the same number of protons.
• Example: Silver has isotopes with 60 and 62 neutrons, affecting its relative atomic mass.
• Relative atomic mass: Average mass based on the natural abundance of isotopes, not a whole number.
• Mass number: Total number of protons and neutrons in a single atom; differs from atomic mass.

Pronunciation Note

• Preferred pronunciation of nucleus is 'nucleus', although 'nuculus' is also accepted.

Conclusion

• Key takeaways:
  • Einstein confirmed the existence of atoms through Brownian motion.
  • Elements are defined by the number of protons.
  • Neutrons stabilize the nucleus.
  • Isotopes cause variations in relative atomic mass.
  • Chemical reactions involve electrons, not the nucleus.

Crash Course Chemistry: Produced by Nick Jenkins, Chemistry consultant Dr. Heiko Langner, sound design by Michael Aranda, graphics by Thought Bubble. Questions and feedback are welcomed in the comments.