development of the model of the atom

• What is the main topic of the video?

  The history of the atom
• What does atomic theory propose about matter?

  Everything is made of tiny particles
• Who originally proposed atomic theory?

  Democritus
• When did Democritus live?

  Around 500 BC
• What did John Dalton describe atoms as?

  Solid spheres
• What did Dalton suggest about different types of spheres?

  They make up different elements
• What model did J.J. Thompson propose in 1897?

  The plum pudding model
• What did Thompson's experiments show about atoms?

  Atoms contain negatively charged particles
• What did Thompson propose about the structure of the atom?

  It has a positive charge with electrons
• What significant experiment did Ernest Rutherford conduct in 1909?

  Fired alpha particles at gold foil
• What did Rutherford expect to happen in his gold foil experiment?

  Alpha particles should pass through
• What was the actual result of Rutherford's gold foil experiment?

  Some alpha particles were deflected
• What did Rutherford conclude from his experiment?

  Atoms have a compact nucleus
• What did Rutherford suggest about the negative charge in atoms?

  It exists in a cloud around the nucleus
• What flaw did Rutherford's model have?

  Electrons should collapse into the nucleus
• What solution did Niels Bohr propose in 1913?

  Electrons orbit the nucleus in shells
• Why is Bohr's idea important?

  It prevents the atom from collapsing
• What did further experiments by Rutherford discover about the nucleus?

  Nucleus contains protons
• Who provided evidence for neutrons in the nucleus?

  James Chadwick
• What are the three main particles in an atom?

  Protons, neutrons, and electrons
• What is the historical progression of atomic theory?

  • Democritus proposed atomic theory (500 BC)
  • John Dalton described atoms as solid spheres
  • J.J. Thompson introduced the plum pudding model
  • Ernest Rutherford discovered the nucleus
  • Niels Bohr suggested electron shells
  • James Chadwick identified neutrons
• What are the key models of the atom in history?

  1. Atomic theory by Democritus
  2. Solid sphere model by Dalton
  3. Plum pudding model by Thompson
  4. Nuclear model by Rutherford
  5. Planetary model by Bohr
• What are the roles of protons, neutrons, and electrons in an atom?

  • Protons: Positive charge, in nucleus
  • Neutrons: Neutral charge, in nucleus
  • Electrons: Negative charge, orbiting nucleus