Monday, April 23, 2007

Workshop Last Week

I should have probably done this before the exam last week, but maybe this will help someone for the final.

So, last week's workshop was all about orbitals in atoms with more than one electron. Here are the main points:
  • Sub-orbitals (s,p,d,f) only differ in energy in atoms with more than one electron. When the sub-orbitals in an orbital (n=1,2,3...) all have the same energy, the atom is called degenerate.
  • s, p, d, and f is the ording of sub-orbitals from lowest to highest energy.
  • Only one emission line is observed on a spectrum of a degenarate atom (like hydrogen) when its electrons jump one energy levels. In non-degenarate atoms, mutiple lines are observed because of the fact that sub-levels (l) must change by + or - in the transition of an electron.
  • Shielding refers to the fact that the core electrons in mutiple-electron atoms shield the atom's valence electrons from the full nuclear charge. Shielding is what makes multiple-electron atoms not degenerate.
  • Periodic trends: ionization energy increases from left to right across a period and decreases top to bottom down a group. The opposite is true for atomic radius.
Thats it!

Wednesday, April 4, 2007

Exam Question Workshop 8

A common thing for teens in Rural WNY to do on dull midsummer days is to blow 2L bottles up. They do this in a non-neferious kind of way, in their open fields. They take a soda bottle and fill it with The Works Toilet Bowl Cleaner, then add balls of Aluminum Foil, cap it off, shake it and run. This reaction can easily explode large pumpkins and has the equation:

NaOH + Al --> Al(OH)3 + Na2O + H2

This reaction is performed at 24C and through your laboratory experiment the Activation Energy was determined to be 48kJ/mol. If these teens wanted to carry this reaction out at 8 times the rate, what would the Temperature have to be?