Tuesday, March 3, 2009
Tues-Day 1
AP Chem- continued explaining the relative strengths of oxo-acids based on the increasing O-H bond polarity due to an increasing number of electron-attracting/withdrawing O's attached to the central atom in a given series of oxo-acids. We then compared the strengths of oxo-acids that have the SAME number of oxygens attached to the central atom but a DIFFERENT central atom. We say that, the more electronegative the central atom, the more polar the O-H bond due to the electron attracting/withdrawing effect of the central atom and therefore, the more acidic the molecule.
We then reviewed the overall explanation of the strength of any acid or relative strengths of any comparable series of acids. To write a correct explanation:
1. Draw the correct Lewis structures of each acid molecule.
2. Compare the Bond POLARITY of the H-X bond (in an oxo-acid, the H-O bond) based on the electronegativity of X or based on the number of electron withdrawing groups attached to the central atom of the molecule.
3. Compare the Bond STRENGTH of the H-X bond; the smaller the distance between the two nuclei (H and X) sharing the electrons, and the greater the Zeff of X on the shared electrons, the STRONGER the bond and the more energy required for the acid to ionize i.e. the weaker the acid.
That's what you have to do; don't leave out a factor even if you end up writing that it is not significant in causing the difference acidity i.e. always consider and write about each factor.
We discussed the REAL reason that a given salt is acidic, basic, or neutral. Salts that contain ions that are conjugates of STRONG acids and bases will form neutral solutions. Why? Because conjugates of STRONG acids or bases are so weak that they are unable to either donate an H+ to water or accept an H+ from water i.e. they do not react with/hydrolyze water thus the solution formed has the same pH as pure water.
We saw that salts that dissociate into ions that are conjugates of WEAK acids or bases will react with/hydrolyze water to form either an acidic or basic solution.
We will discuss more examples tomorrow. Acid-base test is on Day 1 Thursday; there will be questions on ORGANIC chemistry from your winter break assignment so know how to draw and name examples of each type of organic compound and know the various organic reaction types that were assigned.
Bio 6/7- we did a concept map showing the relationship between various stimuli and the receptor cells that are specialized to detect/sense these stimuli.
We then discussed types of drugs and the reason for their general effects on the nervous system.
We discussed the mechanism for drug tolerance i.e. SATURATION of the nerve/dendrite receptors with the drug so that a much higher dosage is required to have any increased effect.
We discussed the difference between physiological and psychological addiction. We also defined drug withdrawal.
Bio 8- we reviewed the structure and functions of the various parts of the brain. Tomorrow we will talk about the relationship between various drugs and neurotransmitters.
We then reviewed the overall explanation of the strength of any acid or relative strengths of any comparable series of acids. To write a correct explanation:
1. Draw the correct Lewis structures of each acid molecule.
2. Compare the Bond POLARITY of the H-X bond (in an oxo-acid, the H-O bond) based on the electronegativity of X or based on the number of electron withdrawing groups attached to the central atom of the molecule.
3. Compare the Bond STRENGTH of the H-X bond; the smaller the distance between the two nuclei (H and X) sharing the electrons, and the greater the Zeff of X on the shared electrons, the STRONGER the bond and the more energy required for the acid to ionize i.e. the weaker the acid.
That's what you have to do; don't leave out a factor even if you end up writing that it is not significant in causing the difference acidity i.e. always consider and write about each factor.
We discussed the REAL reason that a given salt is acidic, basic, or neutral. Salts that contain ions that are conjugates of STRONG acids and bases will form neutral solutions. Why? Because conjugates of STRONG acids or bases are so weak that they are unable to either donate an H+ to water or accept an H+ from water i.e. they do not react with/hydrolyze water thus the solution formed has the same pH as pure water.
We saw that salts that dissociate into ions that are conjugates of WEAK acids or bases will react with/hydrolyze water to form either an acidic or basic solution.
We will discuss more examples tomorrow. Acid-base test is on Day 1 Thursday; there will be questions on ORGANIC chemistry from your winter break assignment so know how to draw and name examples of each type of organic compound and know the various organic reaction types that were assigned.
Bio 6/7- we did a concept map showing the relationship between various stimuli and the receptor cells that are specialized to detect/sense these stimuli.
We then discussed types of drugs and the reason for their general effects on the nervous system.
We discussed the mechanism for drug tolerance i.e. SATURATION of the nerve/dendrite receptors with the drug so that a much higher dosage is required to have any increased effect.
We discussed the difference between physiological and psychological addiction. We also defined drug withdrawal.
Bio 8- we reviewed the structure and functions of the various parts of the brain. Tomorrow we will talk about the relationship between various drugs and neurotransmitters.
# posted by C @ 12:55 PM 
