Thursday, November 30, 2006
Thursday
Honors: we finished up the remaining periodic trends in electron affinity (attraction) and electronegativity. All of these trends will ultimately be related to what elements react with what other elements and how and why they react together - that's our next unit: chemical bonding and attractions.
Don't forget the three main CAUSES of all periodic trends that all relate to Coulomb's Law, which rules over all of chem and physics: (1) Zeff= the MOST important factor in determining the attraction of a nucleus on its electrons (2) OPEL's, which indicate the distance that the electron is from the nucleus, and (3) electron-electron repulsion in a given PEL or between electrons in different sublevels of a PEL.
We have a multiple choice test tomorrow on all notes between and including electron configurations and periodic trends. Don't forget about isoelectronic species and how to compare them.
Regents: we went through the difference between ionic (metal cation to nonmetal anion) and covalent (a nonmetal atom sharing valence electrons with a nonmetal atom) bonds. We related this to salts (ionic) and molecules (covalent).
Tomorrow is one of THE most important lessons of the year: how to NAME compounds and how to DETERMINE the FORMULA of any simple compound based on which elements are combined.
AP: more Lewis structures and shapes; on resonance structures we applied the TOOL of "formal charge" to PREDICT which resonance structure contributes MOST SIGNIFICANTLY to the real structure of the compound. Formal charge is in NO WAY, SHAPE or FORM, actual electric or ionic charge! It is just a little game that chemists can play to predict reality. That game is still on the AP exam even though we have quantum mechanics so that we don't have to play games anymore. Most people don't have QM supercomputers, though, so we will play the "formal charge" game; that works most of the time.
We have "electron-deficient" molecules and "expanded octets" tomorrow. Good times.
Don't forget the three main CAUSES of all periodic trends that all relate to Coulomb's Law, which rules over all of chem and physics: (1) Zeff= the MOST important factor in determining the attraction of a nucleus on its electrons (2) OPEL's, which indicate the distance that the electron is from the nucleus, and (3) electron-electron repulsion in a given PEL or between electrons in different sublevels of a PEL.
We have a multiple choice test tomorrow on all notes between and including electron configurations and periodic trends. Don't forget about isoelectronic species and how to compare them.
Regents: we went through the difference between ionic (metal cation to nonmetal anion) and covalent (a nonmetal atom sharing valence electrons with a nonmetal atom) bonds. We related this to salts (ionic) and molecules (covalent).
Tomorrow is one of THE most important lessons of the year: how to NAME compounds and how to DETERMINE the FORMULA of any simple compound based on which elements are combined.
AP: more Lewis structures and shapes; on resonance structures we applied the TOOL of "formal charge" to PREDICT which resonance structure contributes MOST SIGNIFICANTLY to the real structure of the compound. Formal charge is in NO WAY, SHAPE or FORM, actual electric or ionic charge! It is just a little game that chemists can play to predict reality. That game is still on the AP exam even though we have quantum mechanics so that we don't have to play games anymore. Most people don't have QM supercomputers, though, so we will play the "formal charge" game; that works most of the time.
We have "electron-deficient" molecules and "expanded octets" tomorrow. Good times.
# posted by C @ 5:14 PM 
