Exceptions to Electron Configurations

Electron configurations are another way to represent quantum numbers.  Both electron configurations and quantum numbers indicate the location of electrons while in its ground state for a particular atom.  The periodic table is split into 4 blocks, designated as s, p, d, or f, each representing a different shape for of the orbitals.  This also corresponds to the azimuthal quantum number l (that’s the lowercase letter L).  On the periodic table, s corresponds to groups 1 and 2, p corresponds to groups 13 through 18, and d corresponds to groups 3 through 12.  The f orbitals are found at the bottom of the periodic table and are filled with the inner transition metals, also known as the lanthanide and actinide series or elements.

In the larger subshells of d and f (each with 10 and 14 orbitals, respectively) they sometimes do not fill their orbitals in the predicted manner.  For example, chromium, element 24.  One would expect to have an electron configuration of [Ar] 4s² 3d⁴.  However, the electron configuration for chromium is found to be [Ar] 4s¹ 3d⁵.  One electron from the outer s orbital is promoted to the d subshell.  It is able to do this because the 4s and 3d subshells are very close in energy.  This gives both the outermost s and d subshells a complete set of half-filled orbitals.  This is a more stable configuration because it reduces electron repulsion within orbitals as much as possible and reduces the overall energy.  It holds that other elements found in the same group as chromium behave the same way.

Furthermore, copper behaves similarly.  Cu has an expected electron configuration of [Ar] 4s² 3d⁹ but in reality demonstrates [Ar] 4s¹ 3d¹⁰.  One electron from the outermost s orbital is promoted to the d orbital to give it a complete subshell.  Again, the reason for this has to do with lower energy and greater stability.  The elements found beneath copper on the periodic table behave in a similar fashion.  Filled subshells are the most stable, followed by half-filled subshells and then lastly incomplete subshells.

1.      It has been hypothesized that elements in the f-block elements behave the same way.  Predict which elements you would expect to have exceptional electron configurations and explain why.

2.      Explain why silicon does not demonstrate an electron configuration of [Ne] 3s¹ 3p³.

3.      Identify the other transition metals besides chromium and copper that demonstrate exceptional electron configurations.

AP Chem Review Assignment

The assignment:

1.    Write a short summary of your topic and post it to your blog.  Be sure to include a little heading stating what you were given.  Copying your summary from your textbook, review book, Wikipedia, etc. is considered plagiarism and will be graded accordingly (that means a zero will be given).  Please use these things as sources but write your own unique summary.  If given more than one topic make 2 posts.

2.    Write 2 self-test questions and answers on your summary topic.  Only one question can be multiple choice, the other must be open ended.  Furthermore, at least one question needs to be at the Synthesize or Evaluate level (see reverse). Do NOT post the answers to your questions publicly to your blog, rather send them privately to Ms. Cool.  Please include both the questions and answers when you send them.  Again, plagiarized questions will be rewarded appropriately.

3.    Comment on AT LEAST three other topics written by other people.  These comments need to further the discussion in some way.

a.    Comments can be

                                       i.    adding on to the information (like a piece of information that was missed or is related)

                                      ii.    asking a clarifying question (example: How do you know when to use molarity instead of molality?)

                                    iii.    answering someone’s clarifying question (example: Molarity is used when blah and molarity is used when blah.)

                                     iv.    answering the questions written by the original poster as long as the answer is in detail. 

1.    Good example: The answer is A because you need this formula to solve the question.  This is how to set it up… 

2.    Bad example: The answer is C. 

3.    Rule of thumb – it should take at least 2-3 sentences to answer the question and explain the logic behind your answer. 

b.    Comments cannot be “me too” or “I agree” type comments.  You can make these comments, but they that will NOT count towards your 3 comment minimum.

A note: Blogs are very casual, but remember that you are doing this for a class.  The expectation is that you handle yourself respectfully and in an academic manner.  That doesn’t mean that you can’t “LOL”, but it does mean that you should primarily be using academic language and steering away from text-speak and abbreviations.  People will make mistakes with their information on their topics from time to time.  It is okay and even necessary to correct them because this is for your review.  However, point out the errors in a way that you would like your errors pointed out in front of the class.  In case you are uncertain, this means it should be done in a nice, respectful manner.  Hurtful or disrespectful comments will be deleted as well as points from your grade.

Grading:

·        10 points each for completing your original post.  First post due by Wednesday, April 17^th, 11:59pm; 2^nd by Friday, April 19^th

·        5 points each for submitting your questions and answers properly to Ms. Cool.  Same dates as above

·        5 points for each of your 3 comments, up to a maximum of 30 points.  First round due by, Friday, April 19^th 11:59pm, second round by Monday, April 22^nd, 11:59pm

This assignment is to help prepare you for the AP Exam.  Remember, the more you put into it, the more you will get out of it!

Greetings, this is a test post of my new blog!