Periodic Trends - Graphs & Straws



Periodic Trends: Graphs and Straws

Calculator Version

Introduction:

Positions of elements in the periodic table and their properties are due to their electron configurations. Since electron configurations change in an ordered manner as you move through the periodic table, we can use the periodic table to predict changes in properties of the elements. In Part A of this activity, students graph physical data and determine trends in groups and periods. In Part B of this project, students build dramatic three-dimensional displays of the periodic properties of the elements.

Depending on the stage of chemical training of the students, you might want to start with atomic radius, density, atomic volume, and melting point before moving on to try ionization energies, electron affinities, and electronegativities.

Materials: for each Periodic Table:

|Part A: |Part B: |

|Graphing Calculator |1 96-hole well tray or styrofoam |

|Assigned table of data |Assigned graph |

|Graph Paper |Well plate template |

| |Bag of 40 drinking straws 1/4” OD |

Procedure:

Part A: Periodic Trends in Atomic Data Using TI Calculators

1. On the calculator press the stat button and choose edit to get to the lists. Input the data listed in the following Tables into the lists in the order indicated by your teacher.

(L1 = atomic number, L2 = atomic radii, L3 = electronegativity, L4 = ionization energy)

2. Press the 2nd stat plot to plot List 1 and List 2.

• Highlight Plot 1, press enter.

• Highlight “On”

• Select connected points and the first mark.

• Check Xlist : L1

• Check Ylist : L2

3. Press the window button to adjust your window to fit the data in your lists.

• Set Xmin = 0

• Xmax = 40

• Xscl = 1

• Ymin = 25

• Ymax = 250

• Yscl = 10

4. Press Graph.

5. Use trace and press arrow keys to examine the minimums and maximums on your graph.

6. On your graph paper, hand-sketch the graph using only the maximums and minimums. Label the axes and give your graph a title. (last pages of lab)

7. Write a sentence describing your graph.

8. Press the 2nd stat plot to plot List 1 and List 3. Change Ylist to L3. (2nd 3)

9. Press the window button to plot List 1 to List 3. Adjust the window for the new set of data.

10. Press Graph

11. Use trace and press arrow keys to examine the minimums and maximums on your graph.

12. On your graph paper hand sketch the graph using only the maximums and minimums. Label the axes and give your graph a title. (last pages of lab)

13. Write a sentence describing your graph.

14. Press the 2nd stat plot to plot List 1 and List 4. Change Ylist to L4. (2nd 4)

15. Press the window button to plot List 1 to List 3. Adjust the window for the new set of data.

16. Press Graph

17. Use trace and press arrow keys to examine the minimums and maximums on your graph.

18. On your graph paper hand sketch the graph using only the maximums and minimums. Label the axes and give your graph a title. (last pages of lab)

19. Write a sentence describing your graph.

20. Clear out all lists. Input only the marked data into your graphing calculator.

21. Complete the data table for each of the atomic radius, electronegativity, and ionization energy.

22. Continue to Part B of lab.

Part B: Periodic Trends in Atomic Data Using 3-D Models

1. Place the well plate on top of the grid.

2. Arrange the cut straws on the graph so that the lengths follow the pattern of the graph. Make sure that one end of the straw touches the reference line noted on the graph and the other end touches the point on the graph. The magnitude of the atomic property that is represented by the length of the straw.

3. If you are missing any straws, ask your teacher for some of the matching color and cut these to the proper length. Add these to your bag.

4. Once you have identified the straw that represents the graphed property for that element, insert the straw into the well over the symbol of that element. If you want a permanent display, place a drop of glue on the end of the straw before inserting it into the well.

5. Answer the questions.

6. When you are finished, return the straws to the correct bag for storage.

Name

Partner(s) Name(s)

Period Date:

Periodic Trends: Graphs and Straws

Part A: Periodic Trends in Atomic Data Using TI Calculators

Data Sheet

4. From the graph for atomic radius:

a) What elements represent the maximum for each period?

b) What elements represent the minimum for each period?

5. Write a sentence describing what happens to atomic radii across a period.

6. From the graph of electronegativity:

a) What elements represent the maximum for each period? ______

b) What elements represent the minimum for each period?

7. Write a sentence describing what happens to electronegativity across a period.

8. From the graph of ionization energy:

a) What elements represent the maximum for each period?

b) What elements represent the minimum for each period?

9. Write a sentence describing what happens to ionization energy across a period.

10. What did you notice about the noble gases from your graphs in terms of electronegativity and ionization energy?

11. From the graph for atomic radius:

a) What elements represent the maximum for each group?

b) What elements represent the minimum for each group?

12. Write a sentence describing what happens to atomic radii down a group.

13. From the graph of electronegativity:

a) What elements represent the maximum for each group? ______

b) What elements represent the minimum for each group?

14. Write a sentence describing what happens to electronegativity down a group.

15. From the graph of ionization energy:

a) What elements represent the maximum for each group?

b) What elements represent the minimum for each group?

16. Write a sentence describing what happens to ionization energy down a group.

17. What did you notice about the noble gases from your graphs in terms of electronegativity and ionization energy?

18. Explain the trends of atomic radius, electronegativity, and ionization energy in terms of effective nuclear charge and electron configurations.

Name

Partner(s) Name(s)

Period Date:

Periodic Trends: Graphs and Straws

Part B: Periodic Trends in Atomic Data Using 3-D Models

Atomic Radius

1. What happens to the lengths of the straws as you go from left to right across a row? ___________________________________________________________

2. What happens to the lengths of the straws as you go from top to bottom down a column? ________________________________________________________

Electronegativity

3. What happens to the lengths of the straws as you go from left to right across a row? ___________________________________________________________

4. What happens to the lengths of the straws as you go from top to bottom down a column? ________________________________________________________

Ionization Energy

5. What happens to the lengths of the straws as you go from left to right across a row? ___________________________________________________________

6. What happens to the lengths of the straws as you go from top to bottom down a column? ________________________________________________________

7. Draw arrows on the blank periodic tables to illustrate the periodic trend for each property. Be sure to note whether you see an increase or decrease with direction of the arrow.

| | | |Atomic Radius | | | |

|1 |H |37 | |21 |Sc |162 |

|2 |He |50 | |22 |Ti |147 |

|3 |Li |152 | |23 |V |134 |

|4 |Be |111 | |24 |Cr |130 |

|5 |B |88 | |25 |Mn |135 |

|6 |C |77 | |26 |Fe |126 |

|7 |N |70 | |27 |Co |125 |

|8 |O |66 | |28 |Ni |124 |

|9 |F |64 | |29 |Cu |128 |

|10 |Ne |70 | |30 |Zn |138 |

|11 |Na |186 | |31 |Ga |122 |

|12 |Mg |160 | |32 |Ge |122 |

|13 |Al |143 | |33 |As |121 |

|14 |Si |117 | |34 |Se |117 |

|15 |P |110 | |35 |Br |114 |

|16 |S |104 | |36 |Kr |109 |

|17 |Cl |99 | |37 |Rb |244 |

|18 |Ar |94 | |38 |Sr |215 |

|19 |K |231 | |39 |Y |178 |

|20 |Ca |197 | |40 |Zr |160 |

Electronegativities of the Elements 1-40

The electronegativity is the tendency of an atom to attract to itself electrons within a chemical bond. It follows that this number must always be comparative-compared to the other atom to which it is bonded. Electronegativity is expressed in terms of a relative scale of arbitrary units with fluorine assigned an electronegativity of 4.0.

|Z |Element |E.N. | |Z |Element |E.N. |

|1 |H |2.1 | |21 |Sc |1.3 |

|2 |He |0 | |22 |Ti |1.5 |

|3 |Li |1.0 | |23 |V |1.6 |

|4 |Be |1.5 | |24 |Cr |1.6 |

|5 |B |2.0 | |25 |Mn |1.5 |

|6 |C |2.5 | |26 |Fe |1.8 |

|7 |N |3.0 | |27 |Co |1.8 |

|8 |O |3.5 | |28 |Ni |1.8 |

|9 |F |4.0 | |29 |Cu |1.9 |

|10 |Ne |0 | |30 |Zn |1.6 |

|11 |Na |0.9 | |31 |Ga |1.6 |

|12 |Mg |1.2 | |32 |Ge |1.8 |

|13 |Al |1.5 | |33 |As |2.0 |

|14 |Si |1.8 | |34 |Se |2.4 |

|15 |P |2.1 | |35 |Br |2.8 |

|16 |S |2.5 | |36 |Kr |0 |

|17 |Cl |3.0 | |37 |Rb |0.8 |

|18 |Ar |0 | |38 |Sr |1.0 |

|19 |K |0.8 | |39 |Y |1.2 |

|20 |Ca |1.0 | |40 |Zr |1.4 |

First Ionization Energies of the Elements 1-40

The first ionization energy of an atom is the energy required to remove an electron from a ground state atom in the gas phase:

Atom(g) + energy ( Atom+(g) + e-

The ionization energies give us information about the relative stabilities of valence electrons. The units of ionization energy are kJ/mol.

|Z |Element |I. E. | |Z |Element |I. E. |

|1 |H |1312 | |21 |Sc |627 |

|2 |He |2371 | |22 |Ti |656 |

|3 |Li |520 | |23 |V |647 |

|4 |Be |900 | |24 |Cr |656 |

|5 |B |800 | |25 |Mn |714 |

|6 |C |1086 | |26 |Fe |762 |

|7 |N |1402 | |27 |Co |762 |

|8 |O |1314 | |28 |Ni |733 |

|9 |F |1681 | |29 |Cu |743 |

|10 |Ne |2080 | |30 |Zn |907 |

|11 |Na |496 | |31 |Ga |579 |

|12 |Mg |738 | |32 |Ge |562 |

|13 |Al |577 | |33 |As |946 |

|14 |Si |786 | |34 |Se |946 |

|15 |P |1012 | |35 |Br |1139 |

|16 |S |1000 | |36 |Kr |1351 |

|17 |Cl |1255 | |37 |Rb |405 |

|18 |Ar |1520 | |38 |Sr |550 |

|19 |K |419 | |39 |Y |618 |

|20 |Ca |590 | |40 |Zr |618 |

Atomic Radii

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Electronegativity

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Ionization energy

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