Materials

• Fig. 2.18
• Table 2.5
• Three different colors of pencils, pens, or markers
• Four copies of Fig. 2.19

Procedure

A. Concentration of Elements in Seawater

1. Locate the two elements (H and O) that make up pure water in Table 2.5. Circle these elements in the “seawater” column of Table 2.5.
    
2. Locate the (1) major and (2) minor elements in seawater in Table 2.5. For example, “sulfur” is a major element and “bromine” is a minor element in seawater.
   
   1. Fig. 2.18 shows the placement of the decimal point for each of these categories of elements and can be used to interpret Table 2.5. You may also want to refer back to the text for the definitions of these categories.
   2. Put a “star (*)” next to the major elements in the “seawater” column of Table 2.5.
   3. Put an “cross (X)” next to the minor elements in the “seawater” column of Table 2.5.
       
3. Answer activity questions 1—3.
    

B. System Comparison

1. On Table 2.5 rank the amount of each element in each of the following systems. The rank of “1” should represent the element that is most abundant in each system.
   
   1. seawater
   2. the Earth’s crust
   3. the human body
   4. the sun

You may want to split up this step, and the next step, with other members of your group, for example, you can rank the “seawater” system and other members of your group can rank the other systems.

2. Group the top 15 elements for each system into sets of five. Determine
   
   1. the top five elements for each system (ranks 1–5)  
   2. the elements ranked 6–10 for each system
   3. the elements ranked 10–15 for each system
       
3. Devise a way to color-code each set of five. For example you may code the top five elements in each system as “red”.
    
4. There is a blank periodic table (Fig. 2.19) for each system (seawater, Earth’s crust, the human body, and the sun). On each system’s periodic table, locate the top 15 elements. Color code each set of five elements in the top 15 using the scheme you devised in procedure 5.
    
5. Compare the periodic tables from each system. Answer activity questions 4–7.