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Chemistry, surprisingly enough, plays a large role in the study of Biology. That is why Chapters 2 and 3 of our Biology textbook are devoted to a review of the smallest building blocks of our world. Today in class, our minds were refreshed on the basics of chemistry, particularly atoms and how they bond together.

Unlike our unfortunate rivals in Chem II, us Biology kids do not need to memorize all the elements on the Periodic Table. While about 25 elements are essential for life, the majority of life is made up of carbon, hydrogen, oxygen, and nitrogen. Trace amounts of calcium, potassium, sulfur and phosphorous also exist.

These elements, as well as all the others, bond together based on their electrons. The amount of electrons in the valence shell of the atom determines its chemical behavior. Atoms want to either complete a partially filled valence shell of empty a partially filled valence shell, depending on the number of electrons in that shell. When this happens, bonds between atoms result.

There are both weak bonds and strong bonds in the chemical world. Hydrogen bonds, an attraction between positive and negative ends of molecules, is an example of a weak bond. These bonds only occur between Oxygen and Hydrogen, Nitrogen and Hydrogen and Fluorine and Hydrogen.

Hydrogen Bonding Video (user: mtchemers)

Hydrophilic and hydrophobic interactions also occur between water and another element. The final types of weak bonds are Van derWaals forces and ionic bonds, but we did not discuss them any further in our class today.

Covalent bonds are the strongest bonds in chemistry. These bonds result when two atoms share a pair of electrons between them. This results in the formation of a molecule. Multiple covalent bonds, like double or triple bonds also can result, depending on the number of electron pairs being shared. There are both polar and nonpolar covalent bonds which depend whether of not the electron pair (or pairs) are shared equally between the two atoms. If the electronegativity of one atom is significantly larger than the other, a polar bond occurs.

Finally, hydrogen bonding, like discussed earlier, occurs with water molecules as well. The irregularity of the water molecule gives water some of its unique characteristics. That is the subject of our next chapter, and the next blog as well.

Class was very interesting and brought back some feelings of nostalgia for us, if it is possible to have nostalgic feelings about chemistry.

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Today in AP bio we took our first quiz, which covered materials related to the Chaper 1 notes and reading. We checked on our experiments on seed germination and recorded the results in our Seed Germination Lab excel books on the computer. We began taking notes over Chaper 2, which is a review of chemistry. The section begins with some of the basics of chemistry, including matter and atoms. We then moved on to review some of the elements, such as carbon, oxygen, hydrogen, and nitrogen, which are some of the most important elements in biology. We covered a section on isotopes and bonding properties, and discussed the imortant of valence electrons and valence shells. Next we talked about the different types of bonds and their strengths, including ionic bonds and single, double, and triple covalent bonds. We finished the day discussing polar covalent bonds, which will lead us into our discussion tomorrow about the properties of water.

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