Webquest: Atomic Theories and ModelsVersion 3

Answer these questions on your own sheet of paper, USING COMPLETE SENTENCES, where appropriate (most of the questions, except tables and drawings).

Atom Basics

Go to the website and read the section “Smaller Than Atoms?” Use the information there to answer the following questions:

  1. What makes each element unique?
  2. How are neutrons, protons, and electrons described in the illustration?
  3. Which atomic particles are found inside the nucleus of an atom?
  4. Compare the masses of each subatomic particle to one another.

Early Ideas About Atoms

Go to and read the section on “Early Greek Ideas” in order to answer the following questions:

  1. What was the “basic idea” about matter that Leucippus and Democritus proposed?
  2. How did they use atoms to explain different physical properties?

John Dalton’s Atomic Theory

Go to and use the information found there to answer the following questions:

  1. When did Dalton develop his atomic theory?
  2. What did Dalton say is the reason an element is pure?
  3. How did Dalton explain differences between elements?
  4. What support did Dalton have for his theory that compounds have a constant composition? (2 important parts.)
  5. What is the difference between a theory of atoms, and a model of atoms?

J.J. Thomson and the Electron

Go to use the information there to answer the following questions:

  1. What is the year in which J.J. Thomson discovered the electron?
  2. What was the evidence for “bodies much smaller than atoms”?
  3. What was his model of the atom?

Rutherford and Bohr Break the “Plum Pudding” Model

Go to the website and use the information there to answer the following questions:

  1. What are the differences between Thomson’s “plum pudding” model and the sketch of Rutherford’s atom?
  2. What was the experiment, and its results, that led Rutherford to discard Thomson’s model?

And then visit and answer these questions:

  1. What was the problem with Rutherford’s model that led Bohr to develop his model?

Chadwick (and Rutherford) and the Neutron

Go to and use the information found there to answer the following questions:

  1. What makes up the atomic number?
  2. What makes up the atomic mass?
  3. What observation led Chadwick (and Rutherford) to conclude there must be something besides just the proton in the nucleus of atoms?
  4. What is the something-besides-just-the proton called?