Day 21

This class period will be asynchonous. You don't have to join a discussion today. The homework is due at the end of our normal class period: 12:15. It is Class Review Homework Set #2, a quiz on Canvas.

Class Review Homework Set #2

1. Identify each of the following as resulting in either a chemical or a physical change. Justify each answer. (a) Paper is completely burned, (b) salt is dissolved in water, (c) sodium (Na) is placed in water, (d) an orange is peeled.

2. Which elements would you predict to be the most similar: (a) Na and Rb or (b) Mg and S? Write a conditional argument to support your choice.

3. Does the following argument establish the truthfulness of the conclusion? Explain.

P1 If electrons orbit around the nucleus like planets around the sun, then characteristic colors of light are emitted from atoms as electrons fall back to lower energy states after being excited.

P2 Electrons orbit around the nucleus like planets around the sun.

C Characteristic colors of light are emitted from atoms as electrons fall back to lower energy states after being excited.

4. The first atomic particle to be discovered was the electron. With this discovery the first atomic model was created. Describe the first atomic model and tell why it was discarded.

5. Visit the Gold Foil Experiment link found in the pink media box for Day 18 and write a response indicating whether or not it was useful. Did it help you understand the gold foil experiment better?

6. What does the current model of the atom allow you to say about the position of an electron in an atom?

7. Richard Feynman stated he could describe how nature works, but he could not explain why Nature behaves in this peculiar way. Give an example of natures peculiar behavior from our discussion of atomic theory.

8. How could the red color in fireworks be produced? Explain fully.

9. In class we discussed how different colors are emitted by different elements when an electrical potential was applied. Only certain colors were observed and we called this a line spectrum. Why are only certain colors observed?