1) How can a radioactive tracer be used to follow atoms?

2) fill the blank

Electrons of an atom are known to have their own potential energy.

The ______ charged electrons are attracted to the _________ charged nucleus. To move to an electron shell farther from the nucleus, an electron must _________ energy; energy is _______ when an electron moves a closer shell. (Hint: Use Figure 2.8 “Energy levels of an atom’s electrons” to help you)

3) How does evaporative cooling contribute to the stability of bodies of water (i.e. lakes and ponds) while also preventing from overheating? Explain in terms of the properties of water and heat of vaporization and give an example.

4). Define molarity:

a. What are the units used to define a molar concentration? _____________

b. How does this term relate to aqueous solutions and to biology?