Blogging My Biology Class 20080903

Biology, Eighth Edition, by Campbell & Reece, et al.

Biology, Eighth Edition, by Campbell & Reece, et al.

My notes and thoughts from Biology 111, for Wednesday, September 3, 2008. The entire series can be found here.

We left off before the Labor Day break with polarity and the ability to form hydrogen bonds.

The polarity of the water molecule, having an oxygen to one side and the two hydrogen atoms to the other, gives the molecules a slight attraction to charged molecules, since the oxygen end is going to have a slight negative charge and the hydrogen end is going to have a slight positive charge. This is caused by the unequal sharing of valence e- between the oxygen and the two hydrogens. Because the oxygen pulls harder on the shared e-, they are going to spend more time toward the oxygen, increasing its negative charge a little, and away from the hydrogens, increasing their positive charge a little (actually decreasing their negative charge a little, to be accurate).

That little bit of polarity will cause the oxygen end of one water molecule to be attracted to the hydrogen end of another water molecule (or any other positively charged molecule), and though the effect is small in one pair of molecules, it adds up with millions of molecules.

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Blogging My Biology Class 20080829

Biology, Eighth Edition, by Campbell & Reece, et al.

Biology, Eighth Edition, by Campbell & Reece, et al.

My notes and thoughts from Biology 111, for Friday, August 29, 2008. The entire series can be found here.

Forgive the delay, but I’ve had a ton of stuff to work on.

On Friday, we started out with a review of covalent bonding. Doc re-stressed that in covalent bonding, atoms are sharing one or more pairs of electrons.

Let’s take another look at our covalent bonding notation:

Bonding Notation for Oxygen and Nitrogen

Bonding Notation for Oxygen and Nitrogen

Now note that the two Oxygens share two pairs of e- and the two Nitrogens share three pairs of e-, as noted by the lines and by the dots between them. Also note that in the Lewis Dot diagram, all valence e- are depicted, regardless of whether they are involved in the bonding.

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Blogging My Biology Class 20080827

Biology, Eighth Edition, by Campbell & Reece, et al.

Biology, Eighth Edition, by Campbell & Reece, et al.

My notes and thoughts from Biology 111, for Wednesday, August 27, 2008. The entire series can be found here.

Wednesday’s lecture began with a review of atomic structure, including a reminder that our e * diagrams are 2D representations of 3D space.

Then we moved on to some more basic chemistry.

We focused mostly on electrons, and will continue to, as electrons are what determines reactivity of an atom, and reactivity is what’s really vital to biology.

e orbits are called e shells or energy levels. Each e orbital can hold up to 2 e.

The first energy level has one orbital, because it’s so small, and electrons, having all the same negative electrical charge, repel each other.

The second and third energy levels each contain 4 orbitals, each energy level then is capable of holding 8 e (2 e in each orbital).

Then doc talked about how electrons fill from the innermost energy level, out.

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