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Chapter 2 Blog:  The Chemical Basis of Life I (Aarti)

Page history last edited by Aarti Patel 13 years, 9 months ago

In the first section of this page, you will write a daily summary of that day's class.  For example in  your chapter 2 blog, your first entry should be titled 9/3/10.  You should then write a one or two paragraph summary of that day's lecture, outlining the major points.  In the second section, you are required to add two items (link to a website, video, animation, student-created slide show, student-created PowerPoint presentation) and one journal article pertaining to a topic in this chapter.  A one-paragraph summary must accompany each item describing the main idea and how it applies to the lecture topic.  Please see the PBWorks help guide for assistance embedding video and other items directly in the page.  I will also produce a how-to video on using tables to wrap text around items and other useful tips.  Please see the syllabus for organization and grading details.

 

A.  Daily Blog

 

September 3, 2010

     Today we discussed matter, atoms, and molecules. We talked about the composition of atoms and their properties. Atoms have various orbitals filled with electrons. Each orbital can hold a cetrain number of electrons and has a different shape. The valence shell (outter most shell) is filled when it has 8 electrons. Atoms that do not have 8 electrons in their outter shell bond to other atoms to complete their shells. Atoms bond by the means of chemical bonding. The bonds are either ionic or covalent. In ionic bonds, electrons are transfered from one atom to another. An atom either gains or loses electrons. They become ions or charged atoms. In covalent bonds, electrons are shared between atoms. They could be shared equally between both atoms (nonpolar covalent bonds) or they are unequally shareed (polar covalent bonds). Electrons are unequally shared due to the electronegativity of an atom. Electrons are pulled closer to the atom with greater electronegativity.

     Isotopes are elements that exsit in various forms. The same element differs in the number of nuetrons it has in its nucleus, therefore also changing its mass. Unstable forms of an isotope are called radioisotopes. They are radioactive and do not exsit for long periods of time. when their nucleus decays, they give off energy. Radioisotopes are sometimes used to diagnose cancers. Since cancer cells are rapidly dividing and use large amounts of glucouse, any glucouse would move towards that area of the body. Radioisotpes would travel to the areas of the body where there is rapid division of cells. When the radioisotopes are broken down, they release heat energy. The areas are then detected through a PET scan. Radioisotopes are an easy was to detect any tiem of acncer at an early stage. The problem is the too much radiation if not healthy for the human body. Too much radiation can cause mutations in DNA, which can result in the formation of cancers.


September  8, 2010

     Today we discusses the properties of water. An important question asked was, "why does ice float in water?" It is because of the hydrogen bonds between the molecules. Hydrogen bonds are weak bonds. They become stonger and more stable as the temperature decreases. Water, in the liquid state, has weak hydrogen bonds because the molecules are always moving around. As the temperature decreases, the molecules have less energy to move and organize themselves to form the bonds. One water molecule is most stable when it has four hydrogen bonds. As ice, water molecules are the most stable.  As the the molecules become more stable, they space themselves for the other molecues to form the bonds. Ice is then filled with empty space. This makes ice less dense than liquid water.

     Water is the best solvent of chemical reactions. Since water is a polar covalent molecule, its two ends are slightly charged. This enables water to be attracted to other molecules and easily dissolve them in water. Water can break apart covalent bonds with the process of hydrolisis. Water is also incompressible, which provides support of organisims. Water has a high specific heat, so it takes a long time for water to reach a boiling temperature. Water molecuels attract to each other by the means of cohesion. This help plants, for example, transport water from the roots to the leaves. Water also clings to surfaces, a procces called adhesion. For example, water would stick the surface of the digestive tract and lubricate the track. Water exhibits surface tension. It has a thin sheet, on the suface, of hydrogen bonds (the line between water and air). With this tiny insects are able to walk on top of water.

     We also discussed hydrophillic molecules and hydrophobic molecules. Hydrophillic molecules readily dissolve in water. They are usually ioninicly bonded or are polar covalent molecules. Hydrophobic molecules do not readily dissolve in water. These molecules are covalently bonded. We also talked about pH. pH reffers to the consentration of H+ ions in a solution. It is represented by a scale from 1 to 14: 1 being very acidic, 7 being neutral, and 14 being very basic. A solution is neutral at 7 (water). When the solution has more H+ ions, it is acidic and has a pH below 7. If the solution has fewer amounts of H+ ions, it is basic and has a pH above 7.


 

B.  Useful Materials

 

  • http://www.sciencedaily.com/releases/2006/08/060804104718.htm
    • People who undergo radioisotope treatment, often trigger security alarms. This article gives examples of patients, who recieved radioistope treatment, triggered security alarms at airports, banks, and the White House. These patients are given a certificate stating that the yhave been through radioactive treatment, which they have to carry around.
    • In class, we talked about how too much radiation if bad for the human body. This article explaines how radioactive treatment causes problems for patients that they are unaware of. 

 

 

This video explains the two types of chemical bonds: ionic bonds and chemical bonds. It uses the examples of sodium chloride and water. It explains What happens when electrons are transfered from one atom to another. It aslo talks about how electrons are shared between atoms.

 

http://www.youtube.com/watch?v=QqjcCvzWwww 

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This video lists the various properties of water. It talks about what the properties are and shows examples of each. It mentions the fact that water is a polar. It shows, for example, how water is cohesive and adhesive.

 

http://www.youtube.com/watch?v=4auXUSY9c54 

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Comments (3)

Derek Weber said

at 2:40 am on Sep 9, 2010

9/3: Updated. Nice start. My only suggestion would be to hyperlink to articles rather than pasting the entire URL. To do this, highlight the title of the item > select insert link > paste the URL. Thanks for sharing.

Derek Weber said

at 2:10 am on Sep 11, 2010

9/8: Updated. Nice job.

Aarti Patel said

at 7:26 am on Sep 11, 2010

Thank you

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