IB Chem., 3/9/09 Good Sub note/ Friday’s homework Tests… Lab Friday, Computers Monday Finally a website Electron configurations Homework

Good Sub Note/Friday’s homework I’ve never had 3 days worth of good sub notes so, I’ll find something easy to do at some point this year. Maybe a movie or something I didn’t expect that you would get to the assignment from the book on Friday Therefore we aren’t going to worry about the homework very much

Tests If you haven’t taken the test yet, it will turn into a “0” after school Friday You can still take it any time for full credit but the “0” will be a friendly reminder

Finally a website… I have finally begun work on a website The goal is to post PowerPoints of lessons and whatever assignments I have available in digital form This is a great place to go if you are absent, lose copies of an assignment or would like a copy of my notes Please be aware, nothing beats being in class. My notes and assignments change over the course of the day and the most up-to-date form may not always make it to the website

Electrons Why bother talking about electrons? What did electrons have to do with… Atomic radius? Ionization energy? Electronegativity? Electron affinity? Much of the periodic table is set-up based on electrons but it is useful for more then the number of electrons Make sure you have a periodic table to look at NOW!

Electron configurations Electron orbitals come in 4 flavors: s, p, d & f What different? The number of electrons each holds, how much bigger then H it is and the shape How many electrons do each hold? An s orbital holds 2 electrons A p orbital holds 6 electrons A d orbital holds 10 electrons An f orbital holds 14 electrons

Shapes Each orbital has it’s own very distinctive shape We’ll worry more about this later and I will provide pictures so don’t even bother to try and draw these Click here Click hereWeird!

Filling Orbitals In order to write an electron configuration we need to know the number of electrons an atom has. Where do we get this information? Second we need to know the order that we fill the orbitals and what orbitals are being filled in order

Filling Orbitals This is a lot of numbers but they all tend to be useful For example the electron configuration of Magnesium (Mg), look like: Mg: 1s 2 2s 2 2p 6 3s 2 How do we determine the order?

Filling Orbitals Do you think there may be some exceptions?

Filling Orbitals The orbitals fill in order by the arrows. Written in order, they look like: 1s2s2p3s3p4s3d4p5s4d5p6s4f5d6p7s5f6d7p Oh my! I think you would rather remember it based on the diagram on the last slide The last slide is referred to as the “diagonal rule”

Using the diagram The configuration for nickel (Ni): Try writing a configuration for each of the following: Li, O, Ne, P What about an ion? If a configuration depends on the number of electrons, can we figure out how many electrons an ion has? The configuration for S 2-: How about the configuration for Al 3+ ? F -?

Homework Write the electron configurations for the follow: Atoms: Cs, Se, Cd, U, Pb Ions: I -, O 2-, K +, Fe 3+ Compare the configurations of Se 2- and Kr