Tuesday, January 8, 2008
Tues-Day 1
Bio- HW: if you didn't hand in text 35.2 outline today, do so tomorrow (full credit). Text section 35.3 is due on Thursday; I can return that to you by Friday so that you can study your three outlines over the weekend.
Today, we finished up the digestive system. We noted the types of macronutrients (proteins, carbohydrates, fats, and water) and their purpose in the body. We then looked at micronutrients (vitamins and minerals), which are needed in small quantities daily, and their purpose in the body. On Blackboard, in addition to the worksheet from today, I posted some more digestive system worksheets with answer keys.
We introduced the system that regulates/maintains homeostasis in the body even in a changing environment: the endocrine system.
The endocrine system is a system of 9 glands: hypothalamus, pituitary, pineal, thymus, thyroid, parathyroid, adrenal, islets of Langerhans (of the pancreas), testes (male), ovaries (female).
These glands secrete substances DIRECTLY into the bloodstream for quick circulation throughout the body, HOWEVER, only one SPECIFIC group of "target cells" can bind to a given specific hormone. The target cells will then produce a substance or substances that will help the body maintain homeostasis. The glands are then signalled to stop secreting the hormone once homeostasis is reached (this is known as a negative feedback loop).
Chem 7: we revisited molecular geometry based on our Lewis dot structures and the repulsions among the electron pairs (bonding and nonbonding) around the central atom.
We then got to the POINT of figuring out molecular geometry, which is to determine whether a molecule overall is POLAR (has a definite partial positive side and a definite partial negative side) or NONPOLAR (due to even/symmetric distribution/spread of charge/electrons).
There are three possibilities:
Case 1: If all of the bonds of a molecule are nonpolar, then the molecule MUST BE NONPOLAR due to the equal sharing and distribution of electrons in the molecule.
Case 2a: If the bonds in the molecule are polar, then the molecule is usually also POLAR
EXCEPT!!!!:
Case 2b: if the polar bonds are evenly/symmetrically arranged e.g. as in a CO2 molecule.
Case 2b is THE REASON why you must be able to reason the molecular geometry of a molecule from its Lewis structure. Cases 1 and 2a are pretty intuitive and easy to remember.
We then discussed the weak, temporary intermolecular attractions that can form between nonpolar molecules. These are due to the random motion of electrons within their orbitals that sometimes results in a temporarily uneven distribution of charge/electrons. A temporary partial negative and partial positive pole develops in the molecule which CAUSES other dipoles to form in nearby molecules. Then, these temporarily dipole molecules attract each other (partial positive side of one molecule to the partial negative side of the next molecule) and may stick together (form a liquid) if the molecules are moving slow enough (at a cold enough temperature). That is how, at low temperature or at high pressure, nonpolar molecules that are normally gases at room temperature can liquefy.
We will discuss the relatively stronger attractions among polar molecules.
Chem 8/9:we revisited molecular geometry based on our Lewis dot structures and the repulsions among the electron pairs (bonding and nonbonding) around the central atom.
We then got to the POINT of figuring out molecular geometry, which is to determine whether a molecule overall is POLAR (has a definite partial positive side and a definite partial negative side) or NONPOLAR (due to even/symmetric distribution/spread of charge/electrons).
There are three possibilities:
Case 1: If all of the bonds of a molecule are nonpolar, then the molecule MUST BE NONPOLAR due to the equal sharing and distribution of electrons in the molecule.
Case 2a: If the bonds in the molecule are polar, then the molecule is usually also POLAR
EXCEPT!!!!:
Case 2b: if the polar bonds are evenly/symmetrically arranged e.g. as in a CO2 molecule.
Case 2b is THE REASON why you must be able to reason the molecular geometry of a molecule from its Lewis structure. Cases 1 and 2a are pretty intuitive and easy to remember.
We then discussed the weak, temporary intermolecular attractions that can form between nonpolar molecules. These are due to the random motion of electrons within their orbitals that sometimes results in a temporarily uneven distribution of charge/electrons. A temporary partial negative and partial positive pole develops in the molecule which CAUSES other dipoles to form in nearby molecules. Then, these temporarily dipole molecules attract each other (partial positive side of one molecule to the partial negative side of the next molecule) and may stick together (form a liquid) if the molecules are moving slow enough (at a cold enough temperature). That is how, at low temperature or at high pressure, nonpolar molecules that are normally gases at room temperature can liquefy.
Polar molecules, which each have a permanent partial (+) and a partial (-) side, form relatively stronger attractions among each other; therefore, even at room temperature, polar molecules are typically liquids or solids.
Today, we finished up the digestive system. We noted the types of macronutrients (proteins, carbohydrates, fats, and water) and their purpose in the body. We then looked at micronutrients (vitamins and minerals), which are needed in small quantities daily, and their purpose in the body. On Blackboard, in addition to the worksheet from today, I posted some more digestive system worksheets with answer keys.
We introduced the system that regulates/maintains homeostasis in the body even in a changing environment: the endocrine system.
The endocrine system is a system of 9 glands: hypothalamus, pituitary, pineal, thymus, thyroid, parathyroid, adrenal, islets of Langerhans (of the pancreas), testes (male), ovaries (female).
These glands secrete substances DIRECTLY into the bloodstream for quick circulation throughout the body, HOWEVER, only one SPECIFIC group of "target cells" can bind to a given specific hormone. The target cells will then produce a substance or substances that will help the body maintain homeostasis. The glands are then signalled to stop secreting the hormone once homeostasis is reached (this is known as a negative feedback loop).
Chem 7: we revisited molecular geometry based on our Lewis dot structures and the repulsions among the electron pairs (bonding and nonbonding) around the central atom.
We then got to the POINT of figuring out molecular geometry, which is to determine whether a molecule overall is POLAR (has a definite partial positive side and a definite partial negative side) or NONPOLAR (due to even/symmetric distribution/spread of charge/electrons).
There are three possibilities:
Case 1: If all of the bonds of a molecule are nonpolar, then the molecule MUST BE NONPOLAR due to the equal sharing and distribution of electrons in the molecule.
Case 2a: If the bonds in the molecule are polar, then the molecule is usually also POLAR
EXCEPT!!!!:
Case 2b: if the polar bonds are evenly/symmetrically arranged e.g. as in a CO2 molecule.
Case 2b is THE REASON why you must be able to reason the molecular geometry of a molecule from its Lewis structure. Cases 1 and 2a are pretty intuitive and easy to remember.
We then discussed the weak, temporary intermolecular attractions that can form between nonpolar molecules. These are due to the random motion of electrons within their orbitals that sometimes results in a temporarily uneven distribution of charge/electrons. A temporary partial negative and partial positive pole develops in the molecule which CAUSES other dipoles to form in nearby molecules. Then, these temporarily dipole molecules attract each other (partial positive side of one molecule to the partial negative side of the next molecule) and may stick together (form a liquid) if the molecules are moving slow enough (at a cold enough temperature). That is how, at low temperature or at high pressure, nonpolar molecules that are normally gases at room temperature can liquefy.
We will discuss the relatively stronger attractions among polar molecules.
Chem 8/9:we revisited molecular geometry based on our Lewis dot structures and the repulsions among the electron pairs (bonding and nonbonding) around the central atom.
We then got to the POINT of figuring out molecular geometry, which is to determine whether a molecule overall is POLAR (has a definite partial positive side and a definite partial negative side) or NONPOLAR (due to even/symmetric distribution/spread of charge/electrons).
There are three possibilities:
Case 1: If all of the bonds of a molecule are nonpolar, then the molecule MUST BE NONPOLAR due to the equal sharing and distribution of electrons in the molecule.
Case 2a: If the bonds in the molecule are polar, then the molecule is usually also POLAR
EXCEPT!!!!:
Case 2b: if the polar bonds are evenly/symmetrically arranged e.g. as in a CO2 molecule.
Case 2b is THE REASON why you must be able to reason the molecular geometry of a molecule from its Lewis structure. Cases 1 and 2a are pretty intuitive and easy to remember.
We then discussed the weak, temporary intermolecular attractions that can form between nonpolar molecules. These are due to the random motion of electrons within their orbitals that sometimes results in a temporarily uneven distribution of charge/electrons. A temporary partial negative and partial positive pole develops in the molecule which CAUSES other dipoles to form in nearby molecules. Then, these temporarily dipole molecules attract each other (partial positive side of one molecule to the partial negative side of the next molecule) and may stick together (form a liquid) if the molecules are moving slow enough (at a cold enough temperature). That is how, at low temperature or at high pressure, nonpolar molecules that are normally gases at room temperature can liquefy.
Polar molecules, which each have a permanent partial (+) and a partial (-) side, form relatively stronger attractions among each other; therefore, even at room temperature, polar molecules are typically liquids or solids.
# posted by C @ 11:48 AM 
