Periodic Trends: A Graphical Analysis



Name: _______________________________ Date: ____________________________ P___R___S___

Honors Chemistry

Periodic Trends Lab: A Graphical Analysis

Elements on the periodic table are arranged that exhibit patterns in their properties. In this lab you will graph and analyze 4 periodic properties (atomic radius, electronegativity, ionization energy, and ionic radius).

Graphing – For each graph:

1) The x-axis will be the atomic number AND group number, and the y-axis will be Atomic Radius, Electronegativity, Ionization Energy, and Ionic Radius respectively.

2) The graphs need to have a title, and both axis label with appropriate units.

3) Using a colored pencil and ruler, draw a vertical line between atomic number 2 and 3, 10 and 11, and 18 and 19, separating the elements into the first four periods. Label the period sections appropriately.

4) Analysis Questions - Put the answers on the back of each graph in complete sentences (no questions).

5) Summary of the Trend – Below the title (see the analysis questions for each graph).

Atomic Radius

Circle the points representing the elements in group 1 (atomic # 1, 3, 11, and 19) with a colored pencil and circle data points representing the elements in group 18 (atomic # 2, 10, and 18) with a different color.

1. What is Atomic Radius?

2. Examine your graph. Find the period 2 elements (atomic numbers #3-10). What happens to the atomic radius values as you move across period 2?

3. Find the period 2 elements (atomic numbers #3-10) and the period 3 elements (#11 – 18). Do period 2 and period 3 have the same trend?

4. Examine your graph. Find the group 1 elements (atomic numbers #1, 3, 11, and 19). What happens to atomic radius as you move down the group?

5. Do you see this same trend in group 18 elements (# 2, 10, 18)?

6. Put the Summary of trend for atomic radius below the title on your graph: Atomic radius _______________________ across a period and _________________________ down a group.

Electronegativity

Circle the points representing the elements in group 1 (atomic # 1, 3, 11, and 19) with a colored pencil and then circle data points representing the elements in group 17 (atomic # 9 and17) with a different color.

1. What is electronegativity?

2. Examine your graph. Find the period 2 elements (atomic numbers #3-10). What happens to the electronegativity values as you move across the period?

3. Do period 2 (#3-10) and period 3 (#11 – 18) have the same trend?

4. Examine your graph. Find atomic numbers #1, 3, 11, and 19 that correspond to the elements in Group 1. What happens to electronegativity as you move down the group 1 elements?

5. Do you see this same trend in group 17 elements (# 9 and 17)?

6. Which elements do not have an electronegativity value? Why do you think this is?

7. Put the Summary of trend for electronegativity below the title on your graph: Electronegativity _______________________ across a period and _________________________ down a group.

Ionization Energy

Circle the points representing the elements in group 1 (atomic # 1, 3, 11, and 19) with a colored pencil and then circle data points representing the elements in group 18 (atomic # 2, 10, and18) with a different color.

1. What is ionization energy?

2. Examine your graph. Find the period 2 elements (atomic numbers #3-10). What happens to the ionization energy values as you move across the period?

3. Find the period 2 elements (atomic numbers #3-10) and the period 3 elements (# 11 – 18). Do period 2 and period 3 have the same trend?

4. Examine your graph. Find atomic numbers #1, 3, 11, and 19 that correspond to the elements in Group 1. What happens to ionization energy as you move down the group 1 elements?

5. Do you see this same trend in group 18 elements (# 2, 10, and18)?

6. Put the Summary of trend for ionization energy below the title on your graph: Ionization energy _______________________ across a period and _________________________ down a group.

Ionic Radius

Put a “+” over the points representing the cations in period 1 (atomic # 3-6), period 2 (11-14), period 3 (19-20) with a colored pencil. Put a “-” over the other points representing the anions. Circle the points representing the elements in group 1 (atomic #1, 3, 11, and 19) with a colored pencil and then circle data points representing the elements in group 17 (atomic # 9 and17) with a different color.

1. How does an atom become a cation and an anion?

2. What happens to the ionic radius values of the cations (+) as you move across period 2?

3. What happens to the ionic radius values of the anions (-) as you move across period 2?

4. Do period 2 and period 3 have the same trend for both the cations and anions?

5. Examine your graph. Find atomic numbers #3, 11, and 19 that correspond to the elements in Group 1. What happens to ionic radius as you move down the group 1 elements?

6. Do you see this same trend in group 17 elements (# 9 and17)?

7. At what group # does the ionic radius suddenly increase dramatically from the lowest to the highest? Why?

8. Why is there no ionic radius at the atomic number 2, 10, and 18?

9. Put the Summary of trend for ionic radius below the title on your graph: Ionic radius _______________________ across a period and _________________________ down a group

|Element Symbol |Atomic # |Atomic Radius (pm) |Ionization Energy (kJ/mol) |Electronegativity * (Pauling |Ionic Radius* (pm) |

| | | | |Scale) | |

|H |1 |53 |1311 |2.20 |0.00006 |

|He |2 |31 |2371 |  |  |

|Li |3 |167 |520 |0.98 |60 |

|Be |4 |112 |899 |1.57 |31 |

|B |5 |87 |800 |2.04 |20 |

|C |6 |67 |1086 |2.55 |15 |

|N |7 |56 |1402 |3.04 |171 |

|O |8 |48 |1313 |3.44 |140 |

|F |9 |42 |1680 |3.98 |136 |

|Ne |10 |38 |2080 |  |  |

|Na |11 |190 |496 |0.93 |95 |

|Mg |12 |145 |737 |1.31 |65 |

|Al |13 |118 |577 |1.61 |50 |

|Si |14 |111 |786 |1.90 |41 |

|P |15 |98 |1011 |2.19 |212 |

|S |16 |88 |999 |2.58 |184 |

|Cl |17 |79 |1251 |3.16 |181 |

|Ar |18 |71 |1520 |  |  |

|K |19 |243 |419 |0.82 |133 |

|Ca |20 |194 |590 |1.00 |99 |

*A Blank does NOT mean Zero. You will have some breaks in your graph. Your lines will stop and then start again after the missing points.

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4 Graphs: 60 pts

Analysis Questions: 40 pts

Total: 100 pts

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