Download Electronegativity Periodic Trend

Name _______________________________________ Hour ____________
Periodic Trends: Electronegativity
1. What is the electronegativity of an element?
2. Is the electronegativity the same thing as the electron affinity? Explain.
3. How do you think that the electron affinity might have any impact on the
electronegativity?
4. Robert Mulliken developed the following equation to quantify electronegativity based
on atomic properties: EN = (IE + EA)/2
Where EN= electronegativity, IE = ionization energy, EA = electron affinity. Does
this equation make sense based on what you know about ionization energy and
electron affinity? Explain.
Both a high EA and IE indicate an atom that “likes” electrons, which is consistent
with an electronegative element.
5. Make a prediction about the trend you expect to see in electronegativity:
a. As you move across a period? Why?
b. As you move down a group? Why?
Go to the Periodic Table Live! (http://www.chemeddl.org/resources/ptl/index.html) and
click on the “Chart/Sort” button in the upper right corner. You will use this graphing
feature to answer the questions below.
A new tab will open. The page contains three windows: Periodic Table, Graph and Table.
By default all the elements are selected for graphing; start by clicking the “Deselect All”
button above the miniature periodic table. Now you can choose which elements, groups
and/or periods you would like to graph. Select any period (excluding 1, 6 and 7) on the
periodic table by clicking on the period number on the left.
In the Graph window to the right, click on “X” or “Y” to choose the values you want to
graph on each axes. Choose atomic number (under atomic properties) for the X-axis
and for the Y-axis choose electronegativity (under atomic properties).
6. Do you notice a general trend (don’t worry about the few outliers) in the
electronegativity across the period you chose? Try a couple of other periods- is the
trend consistent? Describe the trend. Is it consistent with your predictions?
7. Explain why you see this trend as you move across a period.
8. Deselect all and choose any one group in the periodic table and use the same X and Y
axes that you used above. Look at a few more groups (avoid the transition metals,
groups 3-12). Do you see a trend in the electronegativity down a group? Is it
consistent between groups? Is it consistent with your predictions?
9. Explain why you see this trend.
11. Which is the most electronegative element?
12. Which is the least electronegative element?
13. Water is a molecule composed of one oxygen and two hydrogen atoms (H2O). Using
the Chart/Sort feature determine the electronegativity of hydrogen and oxygen (you
can choose these elements only). The values will be displayed in the Table window.
What is the electronegativity of each element?
H=__________
O= _________ Which one is more electronegative?
14. What impact does each atoms’ electronegativity have on a chemical bond? What kind
of bond is produced when one atom in a bond is more electronegative than the other
atom in the bond?
15. Draw a Lewis structure for water. Using what you know about the electronegativity
of each element show where there will be a slight negative charge (δ-) and where
there will be a slight positive charge (δ+). What is the net dipole of the molecule?
16. Go to Models 360 (http://www.chemeddl.org/resources/models360/) to check your
work. Find the molecule “water” using the search function at the top. Under the
Display menu on the right, select “Partial Charges” and “Molecular Dipole”. Is the
data from Models 360 consistent with your prediction above?