Developing the Model of the Atom

• What is the earliest model of the atom described?

  Tiny sphere that can't be broken up
• What does the plum pudding model represent?

  A sphere of positive charge with negative electrons
• What is the nuclear model of the atom?

  Positively charged nucleus surrounded by electrons
• How do electrons behave in the Bohr model?

  Electrons orbit the nucleus at certain distances
• What discoveries contributed to the development of the atomic model?

  Electron discovery and alpha scattering experiment
• What did Niels Bohr's theoretical calculations agree with?

  Experimental data
• What was the first positive particle found in the atom?

  Proton
• What did the alpha scattering experiment show about gold foil?

  Most alpha particles passed through
• What does the radius of an atom measure?

  1 x 10⁻¹⁰ m
• Where is most of the mass of an atom concentrated?

  At the center (nucleus)
• What charge does the nucleus of an atom have?

  Positively charged
• Who proved the existence of neutrons?

  James Chadwick
• How much smaller is the nuclear radius compared to the atom's radius?

  About 10,000 times smaller
• What can happen to electrons when they absorb EM radiation?

  They move to higher energy levels
• What occurs when electrons emit EM radiation?

  They move to lower energy levels
• What is the overall electric charge of an atom?

  Zero, number of electrons equals protons
• What are the key models of the atom in history?

  • Tiny sphere model
  • Plum pudding model
  • Nuclear model
  • Bohr model
• What are the main components of the current atomic model?

  • Nucleus (positively charged)
  • Protons (+1 charge)
  • Electrons (-1 charge)
  • Neutrons (neutral charge)
• What are the processes involving electrons in the atom?

  • Absorb EM radiation: move to higher energy levels
  • Emit EM radiation: move to lower energy levels