Activity 14.2, 16.3 – Periodic Trends, Electronegativity & Bond Types

 

Trends in Atomic and Ionic Radii

 

For questions 1-4, look at figure 14.9 on p. 400.

 

1)      For the group 1A metals

a)      how does the atomic radius (in gray) change as you go down the groups?

 

b)      how does the ionic radius (in blue) change as you go down the groups?

 

c)      how does the ionic radius (radius of the cation) compare to the atomic radius?

 

2)      For the group 2A metals

a)      how does the atomic radius (in gray) change as you go down the groups?

 

b)      how does the ionic radius (in blue) change as you go down the groups?

 

c)      how does the ionic radius (radius of the cation) compare to the atomic radius?

 

3)      For the group 7A halogens (nonmetals)

a)      how does the atomic radius (in green) change as you go down the groups?

 

b)      how does the ionic radius (in orange) change as you go down the groups?

 

c)      how does the ionic radius (radius of the anion) compare to the atomic radius?

 

4)      In terms of atomic structure, how can you explain the general trend in atomic radius as you go down a group?  (read “Group Trends” on p. 400)

 

5)      In terms of atomic structure, how can you explain why the ionic radii of cations are smaller than their atomic radii and the ionic radii of anions are larger than their atomic radii? (read “Group Trends, p. 404)

 

 

 

For questions 6-7, look at figure 14.10 on p. 401.

 

6)      What is the general trend for what happens to atomic radius as you move from left to right across a period?

 

 

7)      Are there exceptions to the general trend noticed in question #6?  If so, where?

 

 

8)      In terms of atomic structure, how can you explain the general trend in atomic radius as you go across a period?  (read “Periodic Trends” on p. 400)

 

Trends in Ionization Energy

 

9)      What is ionization energy? (see p. 401)

 

For questions 10-11, look at figure 14.12 on p. 403.

 

10)  What is the general trend in ionization energy as you move down a group?

 

 

11)  What is the general trend in ionization energy as you move from left to right across a period?

 

 

12)  In terms of atomic structure, give reasons for the two trends in questions 10 and 11? (read “Group Trends” and “Periodic Trends” on p. 402-403)

 

Trends in Electronegativity

 

 

13)  What is electronegativity? (see p. 405)

 

 

14)  Open an Excel Spreadsheet on your computer.

a)      Go to  http://environmentalchemistry.com/yogi/periodic/electronegativity.html. 

b)      Left click and then highlight the four columns of the table, “Periodic Table of Elements - Sorted by Electronegativity (Pauling)”.  Under “Edit” click “Copy” or use Ctrl-C to copy.

c)      Go to your spreadsheet.  Type EN, element, symbol, and atomic # into cells A1, B1, C1 and D1 of your spreadsheet respectively.

d)      Click cell A2 of your  spreadsheet.  Under “Edit” click “Paste” or use Ctrl-V to paste. You should now have the data from the table in the first 4 columns of your spreadsheet.

e)      Left click and drag your mouse across columns A, B, C and D to highlight them.

f)        Under the “Data” menu choose”Sort”.  In the window that comes up, have it sort in ascending order by “atomic #”.

g)      Again higlight columns A, B, C and D if they aren’t already. Under the “Insert” menu choose “Chart”.

h)      In the window that pops up, choose the “XY Scatter” with the data points connected by lines and then “Next”.

i)        The next window should give your data range as “=Sheet1!$A$1:$D$99” and “series in columns”.  Click the “Series” tab at the top.

j)        Leave “Name” blank.  “X values” should read “=Sheet1!$D$2:$D$99” and “Y Values” should read “=Sheet1!$A$2:$A$99”.  This will put electronegativity in column A on the y-axis and atomic number in column A on the x-axis. Click “Next”.

k)      Click the “Gridlines” tab at the top.  Click “major” and “minor” for the x-axis and “major for the y-axis. 

l)        Click the “Titles” tab at the top. Give your graph a name and label the x and y axes.

m)    Click the “Legend” tab at the top and unclick “show legend”.

n)      Click “Next” and then “Place chart as new sheet”.

o)      On your chart, click the x-axis and choose “Format gridlines” and then the “scale” tab.. Unclick “Auto” for the first four boxes.  Make the “mimimum” = 0, the “maximum” = 110, the “major unit” = 10 and the “minor unit” = 2. Click “OK”.

p)      Print your chart.

q)      On your chart, write the chemical symbols of the Group 1A  and 7A elements next to their correct points (use your periodic table and the atomic numbers to do this). 

 

15)  What is the general trend in electronegativity as you move down a group? Explain.

 

 

16)  What is the general trend in electronegativity as you move from left to right across a period? Explain.

 

 

MAKE SURE YOU STAPLE YOUR CHART TO THIS HANDOUT BEFORE PASSING IN.

 

Electronegativity and Bond Types

 

Read section 16.3.

 

17)  What is a non-polar covalent bond?

 

18)  What is a polar covalent bond?

 

19)  The hydrogen-chlorine bond is polar covalent.  What are two ways of showing the partial charge that each acquires?

 

 

 

20)   When does an ionic bond form? (see the bottom of page 461)

 

 

21)    Fill in the chart below:

 

electronegativity difference

most probable bond type

example

 

nonpolar covalent

 

 

moderately polar covalent

 

 

very polar covalent

 

 

ionic

 

 

22)  In each case, determine if the bond is nonpolar covalent, moderately polar covalent, very polar covalent, or ionic. If polar covalent be sure to assign the correct partial charge  ( d+ or d- ) to each element. Show all work. (use the chart of electronegatvities in your book on p. 405)

 

 

a)      N-N

 

 

b)      H-F

 

 

c)      Si-S

 

 

d)      Na-Cl

 

 

e)      Mg-O