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Activity: Elemental Abundance in Nature

NGSS Science and Engineering Practices:

NGSS Crosscutting Concepts:

NGSS Disciplinary Core Ideas:

Materials

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

<p><strong>Fig. 2.18.</strong> Placement of the decimal point to show concentrations of major, minor, and trace elements in 1,000 g of seawater.</p><br />

 


 

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.

  1. 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
       
  2. Devise a way to color-code each set of five. For example you may code the top five elements in each system as “red”.
     
  3. 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.
     
  4. Compare the periodic tables from each system. Answer activity questions 4–7.
Activity Questions: 
  1. How many major elements are there in seawater? Which are the two minor elements with the highest concentration? What compound do these elements form?
     
  2. How many minor elements are there in seawater? How many trace elements are there?
     
  3. Aside from the elements H and O that make up pure water what is the total ppt of the other elements that make up seawater?
     
  4. What are the top two elements in each system? Why do you think this is?
     
  5. What are the similarities and differences you noticed between the elemental abundances in each system?
     
  6. What is the source of dissolved substances in the ocean? How does this relate to the abundances of the elements in the earth’s crust and seawater?
     
  7. Which system had abundances that are most similar to seawater? Why do you think that might be?
Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.