Name: _________________________________________ Date:____________________________
Homework 8 – OPTIONAL!!! DO NOT TURN IN!!!
1.) Determine which species would have the more negative Electron Affinity value: (circle is fine!!) a.
Li or F b.
Cs or At c.
C or Pb
Remember that the more negative the EA, the more the species wants to lose electrons.
Non-metals want to lose electrons more than metals!!
2.) Write the electron configurations – DO NOT USE THE NOBLE GAS CONFIGURATION!! – for the following a.
K +1 :
1s 2 2s 2 2p 6 3s 2 3p 6 4s 0 b.
Cu +2 :
1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 9 c.
Cr +2 :
1s 2 2s 2 2p 6 3s 2 3p 6 4s 0 3d 4 d.
Cr +3 :
1s 2 2s 2 2p 6 3s 2 3p 6 4s 0 3d 3 e.
Cr +6 :
1s 2 2s 2 2p 6 3s 2 3p 6 4s 0 3d 0 f.
Mg +2 :
1s 2 2s 2 2p 6 3s 0 g.
Cl -1 :
1s 2 2s 2 2p 6 3s 2 3p 6

3.) Put the following ions in order of increasing size, with the smallest ion on the left and the largest on the right: a.
Li +1 , C +4 , B +3 , Be +2
C +4 < B +3 < Be +2 < Li +1
All have the same number of electrons (2 electrons), the more protons there are, the more they can pull on the remaining electrons, the smaller the species b.
I -1 , Sb -3 , Te -2
I -1 < Te -2 < Sb -3
All species have the same number of electrons (54 electrons), the more electrons compared to the protons, the less pull the protons have on those added electrons and the farther away from the nucleus those electrons are
Even though we have not talked about it, the following questions come from making observations off of tables in the notes (bond strength and bond length!): using those tables, answer the following questions
1.) Examining the tables, what trend is observed in bond strength with respect to bond length.
The shorter the bond the stronger the bond. The longer the bond, the weaker the bond.
Short bonds = strong bonds
Long bonds = weak bonds
2.) Consider the series Cl
2
, Br
2
, and I
2
. What trend is observed in bond strength? Comment on the size of I, Br, and Cl. Considering the size of each atom, what trend would you predict for bond length (e.g. the Cl-Cl bond compared to the Br-Br bond compared to the I-I bond?
As size increases down a column, so does the bond length. The bigger the atoms, the farther away the centers (nuclei) are from one another. The longer the bond, the weaker the bond!
We would predict that since Cl is smaller than Br, and Br is smaller than I, that Cl-Cl would be a shorter (and therefore stronger) bond than Br-Br, which is shorter (and therefore stronger) than I-I.
See picture below

Length 1:
Length 2:
3.) Does the table of average values of bond length confirm your predictions of bond length, briefly explain!
Yes, the larger the atom, the longer bonds it forms with other atoms
4.) Based on your knowledge of size, and using the table, arrange the following sets in order of increasing bond length, comment if there are any trends that you observe!!: a.
H-F, H-I, H-Cl
H-F < H-Cl < H-I iodine is largest so it should have the longest bond length, fluorine is smallest so it should have the shortest bond length b.
N-H, N-S, N-O
N-H < N-O < N-S
H is smallest so it should have the shortest bond length with N, while S is largest, so it should have the longest bond length with N c.
C-S, C=O, C-O
C=O < C-O < C-S
Double bonds are shorter than single bonds!!! S is bigger than O so it should have a longer bond length with C than O does