Tuesday, January 22, 2008
Tues-Day 2
Bio- we finished our discussion of the respiratory system by focusing on the breathing mechanism:
the medulla oblongata of the brain detects a slight increase in CO2 in the blood, causing the medulla to send a chemical signal to the diaphragm. The diaphragm contracts DOWNWARD and the rib cage widens a little which causes the chest cavity to expand, which LOWERS the air pressure inside the lungs. That causes air to rush in from the higher air pressure surroundings. The diaphragm the relaxes and the rib cage returns to its unexpanded position causing the chest cavity volume to decrease, which increases the air pressure in the lungs. This now higher pressure air is forced out of the lungs to the lower air pressure surroundings. Then, the cycle repeats usually about 15 times per minute. So, overall, this is how oxygen is delivered to the alveoli in the lungs where it then diffuses into the pulmonary capillaries and carbon dioxide diffuses from the capillaries into the alveoli. The carbon dioxide is then excreted as you exhale.
We also discussed certain diseases of the respiratory system such as bronchitis, pneumonia, emphysema, and lung cancer.
Chem 7/8- NOTE: on the hw packet, I will not be grading the section on "oxidation numbers of the atoms within the polyatomic ion" because we did not get to that yet. Also, for ANY binary (two element) ionic compound/salt, the oxidation number of the metal is the SAME as its ionic charge e.g. Fe 2+ has an oxidation number of +2 and the oxidation number of the nonmetal is the SAME as its ionic charge e.g. P 3- has an oxidation number of -3; so that doesn't require any extra work or computation.
We continued our practice of naming salts and molecules. We practiced with salts of polyatomic ions noting that for any compound that has an empirical formula (formula unit) with more than one polyatomic ion, that ion must be in parentheses... e.g. Ca(NO3)2 However, if there is only one of the polyatomic ion in the empirical formula (formula unit), then you CANNOT use parentheses...e.g NaNO3
We discussed the STOCK SYSTEM for molecules with which me must use "OXIDATION NUMBERS" for the nonmetals in the molecule. You must consider ONLY the second element in the formula FIRST. That element is your anchor and it is GUARANTEED that atoms of that particular element have their most NEGATIVE (topmost!) oxidation number. Then, from the rest of the formula, you must make the oxidation numbers BALANCE in the same way that you make TRUE IONIC CHARGES balance in salts. The oxidation number of the FIRST (less electronegative) element in the molecule is then written as a ROMAN NUMERAL after the element's name in the formula followed by the second element's truncated name with "ide" as a suffix: that means, for example, CO2 is carbon IV oxide because O is almost always -2 and there are two O's in the molecule, the one C must have a +4 oxidation number.
We then briefly discussed the old-school "ous" vs. "ic" suffixes for salts of transition metals.
We finished our molecular model discussion noting the universal truth that ALL trigonal pyramid and V-shaped molecules MUST BE polar due to their asymmetric charge distribution.
Chem 9- NOTE: on the hw packet, I will not be grading the section on "oxidation numbers of the atoms within the polyatomic ion" because we did not get to that yet. Also, for ANY binary (two element) ionic compound/salt, the oxidation number of the metal is the SAME as its ionic charge e.g. Fe 2+ has an oxidation number of +2 and the oxidation number of the nonmetal is the SAME as its ionic charge e.g. P 3- has an oxidation number of -3; so that doesn't require any extra work or computation.
We continued our practice of naming salts and molecules. We practiced with salts of polyatomic ions noting that for any compound that has an empirical formula (formula unit) with more than one polyatomic ion, that ion must be in parentheses... e.g. Ca(NO3)2 However, if there is only one of the polyatomic ion in the empirical formula (formula unit), then you CANNOT use parentheses...e.g NaNO3
We discussed the STOCK SYSTEM for molecules with which me must use "OXIDATION NUMBERS" for the nonmetals in the molecule. You must consider ONLY the second element in the formula FIRST. That element is your anchor and it is GUARANTEED that atoms of that particular element have their most NEGATIVE (topmost!) oxidation number. Then, from the rest of the formula, you must make the oxidation numbers BALANCE in the same way that you make TRUE IONIC CHARGES balance in salts. The oxidation number of the FIRST (less electronegative) element in the molecule is then written as a ROMAN NUMERAL after the element's name in the formula followed by the second element's truncated name with "ide" as a suffix: that means, for example, CO2 is carbon IV oxide because O is almost always -2 and there are two O's in the molecule, the one C must have a +4 oxidation number.
the medulla oblongata of the brain detects a slight increase in CO2 in the blood, causing the medulla to send a chemical signal to the diaphragm. The diaphragm contracts DOWNWARD and the rib cage widens a little which causes the chest cavity to expand, which LOWERS the air pressure inside the lungs. That causes air to rush in from the higher air pressure surroundings. The diaphragm the relaxes and the rib cage returns to its unexpanded position causing the chest cavity volume to decrease, which increases the air pressure in the lungs. This now higher pressure air is forced out of the lungs to the lower air pressure surroundings. Then, the cycle repeats usually about 15 times per minute. So, overall, this is how oxygen is delivered to the alveoli in the lungs where it then diffuses into the pulmonary capillaries and carbon dioxide diffuses from the capillaries into the alveoli. The carbon dioxide is then excreted as you exhale.
We also discussed certain diseases of the respiratory system such as bronchitis, pneumonia, emphysema, and lung cancer.
Chem 7/8- NOTE: on the hw packet, I will not be grading the section on "oxidation numbers of the atoms within the polyatomic ion" because we did not get to that yet. Also, for ANY binary (two element) ionic compound/salt, the oxidation number of the metal is the SAME as its ionic charge e.g. Fe 2+ has an oxidation number of +2 and the oxidation number of the nonmetal is the SAME as its ionic charge e.g. P 3- has an oxidation number of -3; so that doesn't require any extra work or computation.
We continued our practice of naming salts and molecules. We practiced with salts of polyatomic ions noting that for any compound that has an empirical formula (formula unit) with more than one polyatomic ion, that ion must be in parentheses... e.g. Ca(NO3)2 However, if there is only one of the polyatomic ion in the empirical formula (formula unit), then you CANNOT use parentheses...e.g NaNO3
We discussed the STOCK SYSTEM for molecules with which me must use "OXIDATION NUMBERS" for the nonmetals in the molecule. You must consider ONLY the second element in the formula FIRST. That element is your anchor and it is GUARANTEED that atoms of that particular element have their most NEGATIVE (topmost!) oxidation number. Then, from the rest of the formula, you must make the oxidation numbers BALANCE in the same way that you make TRUE IONIC CHARGES balance in salts. The oxidation number of the FIRST (less electronegative) element in the molecule is then written as a ROMAN NUMERAL after the element's name in the formula followed by the second element's truncated name with "ide" as a suffix: that means, for example, CO2 is carbon IV oxide because O is almost always -2 and there are two O's in the molecule, the one C must have a +4 oxidation number.
We then briefly discussed the old-school "ous" vs. "ic" suffixes for salts of transition metals.
We finished our molecular model discussion noting the universal truth that ALL trigonal pyramid and V-shaped molecules MUST BE polar due to their asymmetric charge distribution.
Chem 9- NOTE: on the hw packet, I will not be grading the section on "oxidation numbers of the atoms within the polyatomic ion" because we did not get to that yet. Also, for ANY binary (two element) ionic compound/salt, the oxidation number of the metal is the SAME as its ionic charge e.g. Fe 2+ has an oxidation number of +2 and the oxidation number of the nonmetal is the SAME as its ionic charge e.g. P 3- has an oxidation number of -3; so that doesn't require any extra work or computation.
We continued our practice of naming salts and molecules. We practiced with salts of polyatomic ions noting that for any compound that has an empirical formula (formula unit) with more than one polyatomic ion, that ion must be in parentheses... e.g. Ca(NO3)2 However, if there is only one of the polyatomic ion in the empirical formula (formula unit), then you CANNOT use parentheses...e.g NaNO3
We discussed the STOCK SYSTEM for molecules with which me must use "OXIDATION NUMBERS" for the nonmetals in the molecule. You must consider ONLY the second element in the formula FIRST. That element is your anchor and it is GUARANTEED that atoms of that particular element have their most NEGATIVE (topmost!) oxidation number. Then, from the rest of the formula, you must make the oxidation numbers BALANCE in the same way that you make TRUE IONIC CHARGES balance in salts. The oxidation number of the FIRST (less electronegative) element in the molecule is then written as a ROMAN NUMERAL after the element's name in the formula followed by the second element's truncated name with "ide" as a suffix: that means, for example, CO2 is carbon IV oxide because O is almost always -2 and there are two O's in the molecule, the one C must have a +4 oxidation number.
# posted by C @ 1:30 PM 
