1. Scientists and Their Experiments
By Tina August

2. Name the Scientist
This scientist said it was impossible to know both the position and momentum of electrons in a particular instant.

3. Answer
Werner Heisenberg

4. Name the Scientist
This scientist fired alpha particles at gold foil and observed how they were scattered.

5. Answer
Ernest Rutherford

6. Name the Scientist
This scientist proposed the arrangement of the elements on the period table based on the trends of known elements

7. Answer
Dmitri Mendeleev

8. Name the Scientist
This scientist watched the deflection of charges in a cathode ray tube and put forth the idea that atoms are composed of positive and negative charges.

9. Answer
J.J. Thomson

10. Name the Experiment
Robert Millikan

11. Answer
Millikan calculated the charge on an electron by examining the behavior of charged oil drops in an electric field.

12. Name the Theory
Max Planck

13. Answer
Planck developed the Quantum Theory by figuring out that electromagnetic energy is quantized. This means for a given frequency of radiation, all possible energies are multiples of a certain unit of energy called a quantum. Energy changes occur in small steps. E = hv is the constant.

14. Name the Theory
John Dalton

15. Answer
Dalton was the first to present some basic ideas about atoms: There are many different kinds of atoms called elements, which combine to form compounds that contain the same ratio of elements.

16. What is the Significance?
The de Broglie Hypothesis

17. Answer
Louis de Broglie said that all matter has wave characteristics, meaning that sometimes the behavior of electrons is better described in terms of waves than particles.

18. What is the Significance?
The Heisenberg Uncertainty Principle

19. Answer
Werner Heisenberg’s principle meant, in terms of atomic structure, that electron orbitals do not represent specific orbits like those of planets. An orbital is a probability function describing the possibility of finding an electron in that space.

20. What is the Significance?
The Bohr Model

21. Answer
Neil Bohr used the quantum theory to predict that electrons orbit the nucleus at specific, fixed radii. This works for atoms and ions with only one electron, not more complex ones.