THe chemical context of life ch2

THe chemical context of life ch2 - The Chemical Context Of...

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The Chemical Context Of Life CHAPTER 2 CHAPTER 2 PAGE 1 : Elements Life depends on chemical reactions Matter takes up space and occupies mass There are 92 naturally occurring elements 25 of the 92 elements are essential to life CHAPTER 2 PAGE 1 : Elements Four elements, ___Hydrogen Oxygen, Carbon, Nitrogen______ make up 96% of living matter Most of the remaining 4% is accounted for by P, Ca, S, K Trace elements are required in small amounts, usually as catalysts Chapter 2 Page 2 : Atoms Atoms composed of protons, neutrons and electrons Atomic number = # protons Atomic mass /wt = protons + neutrons, we will not differentiate the two terms Electrons have orbitals and corresponding energy levels The outermost orbital is called the valence shell. This is the part of the atom that takes part in chemical reactions. “Valence” = denotes the bonding capacity of an atom. Number of electrons needed Valence Electrons = the number of unpaired electrons in the outermost orbital
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This note was uploaded on 04/07/2008 for the course BSC 2010c taught by Professor Janewaterman,pamelathomas during the Spring '07 term at University of Central Florida.

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THe chemical context of life ch2 - The Chemical Context Of...

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