Explain why it is important that mercury be kept out of streams and waterways.
Determine If you were going to try to get the noble gas argon to combine with another element, would fluorine be a good choice for the other element? Explain.
Use the figure below to answer question 20.
Predict How would life on Earth be differ- ent if the atmosphere were 80 percent oxy- gen and 20 percent nitrogen instead of the other way around?
Compare and contrast Na and Mg, which are in the same period, with F and Cl, which are in the same group.
25. Ask Questions Research the contribution that Henry G. J. Moseley made to the development of the modern periodic table. Research the background and work of this scientist. Write your findings in the form of an interview.
Elements at Room Temperature Make a bar graph of the representative elements that shows how many of the elements are solids, liquids, and gases at room temperature.
Calculate Using the information that you col- lected in question 26, calculate the percentage of solids, liquids, and gases within the repre- sentative elements.
Interpret Data The periodic table shows trends across the rows and down the columns. In this portion of the periodic table, the relative size of the atom is repre- sented by a ball. What trend can you see in this part of the table for relative size?
Evaluate It is theorized that some of the actinides beyond uranium were once pres- ent in Earth’s crust. If this theory is true, how would their half-lives compare with the half-life of uranium, which is 4.5 bil- lion years?
Recognize Cause and Effect Why do photogra- phers work in low light when they work with materials containing selenium?
Use the figure below to answer question 28.
28. Element Details For each element shown, give the element’s period and group number; whether the element is a metal or a nonmetal; and whether it is a solid, liquid, or gas at room temperature.
b o o k k . m s s c i e n c e . c o m / c h a p t e r _ r e v i e w
CHAPTER REVIEW K ◆