History of the Atom

• What experiment did Rutherford conduct to suggest a new model for the atom?

  The alpha particle scattering experiment
• What did Rutherford's evidence lead him to propose about the structure of the atom?

  A new model called the nuclear model
• What are the key features of the nuclear model of the atom?

  • The mass of an atom is concentrated at its center, the nucleus
  • The nucleus is positively charged
• Who discovered the electron nearly 100 years after Rutherford's experiment?

  JJ Thomson
• What model did JJ Thomson propose after discovering the electron?

  The plum pudding model of the atom
• What is the plum pudding model of the atom?

  • The atom is a ball of positive charge
  • Negative electrons are embedded in it, like currants in a Christmas pudding
• In what year did Ernest Rutherford design his experiment to test the plum pudding model?

  1909
• What was the purpose of Rutherford's experiment with alpha particles and gold foil?

  To test the plum pudding model of the atom
• What were the results of Rutherford's experiment with alpha particles fired at gold foil?

  • Most alpha particles went straight through the foil
  • A few were scattered in different directions
• Who created the plum pudding model?

  J.J Thomson
• Who discovered neutrons?

  James Chadwick
• Who created The Nuclear Model?

  Ernest Rutherford
• What are the columns and rows called in the periodic table?

  Groups and Periods
• How are elements ordered in thr periodic table?

  Order of atomic number
• Differences between the plum pudding model and the nuclear model.

  The plum pudding model was a ball of positive charge whereas the Nuclear model only the nucleus is positive.

  
  

  Electrons in the plum pudding model are just embedded in the model whereas the nuclear model they are arranged in shells.

  
  

  In the nuclear model the mass is concentrated in the nucleus whereas the plum pudding model it's spread out.
• What did Neil Bohr change about the nuclear model?

  The electrons orbitted the nucleus in shells.

  They electrons were at specific distances from the nucleus.
• What do atoms consist of?

  An atom consists of a nucleus containing protons and neutrons, surrounded by electrons in shells.
• What are the early ideas about atoms according to John Dalton?

  • All matter is made of tiny particles called atoms.
  • Atoms are indivisible spheres.
  • Dalton published his ideas in 1803.
• Who discovered the electron and when?

  J J Thomson discovered the electron in 1897.
• What is the plum pudding model of the atom?

  The plum pudding model suggests that an atom is a ball of positive charge with negative electrons embedded in it.
• What experiment did Ernest Rutherford design to test the plum pudding model?

  Rutherford designed an experiment where positively charged alpha particles were fired at thin gold foil.
• What were the results of Rutherford's alpha particle scattering experiment?

  Most alpha particles went straight through the foil, but a few were scattered in different directions.
• What model did Rutherford propose based on his experiment?

  Rutherford proposed the nuclear model of the atom.
• What are the key features of the nuclear model of the atom?

  • The mass of an atom is concentrated at its center (the nucleus).
  • The nucleus contains protons and neutrons.
  • The nucleus is positively charged.
• What is the charge of the nucleus?

  The nucleus is positively charged.