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Chem%20140A%20lecture%20Notes%20%20%20Fall%202008%20Ch1

Chem%20140A%20lecture%20Notes%20%20%20Fall%202008%20Ch1 -...

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Chemistry 140A Fall 2008 (K. Albizati) 1 What is Organic Chemistry and why is it important? Old definition – chemistry of compounds from living organisms New definition – chemistry of compounds which contain carbon Nature has selected this element as the base element of life processes because it is able to form very strong covalent bonds to itself and to other elements. This enables highly complicated compounds, chemical reactions and chemical reaction pathways. Our bodies are just walking bags of chemicals inter-reacting which allow complex events, like locomotion, vision, speech, thought and others. If you want to understand the field of medicine, you must understand biochemistry and Molecular Biology. To understand Biochem and Mol bio you must have a firm understanding of organic chemistry. Review – Atoms Most of the mass resides in the nucleus containing protons and neutrons. This is surrounded by a cloud of electrons populating orbitals which describe the probability of where an electron may be found. This cloud is about 2Å in diameter which means atoms are about 2Å. A Molecule is made up of atoms held together by chemical bonds. Why do bonds form? Two atoms will form a bond only if it is energetically favorable --- that is if energy is released when the bond is formed. Everything in life tends toward lower energy states in the long run. So, it makes sense that to break a chemical bond you must put energy into the system. Two main causes of bonding are related to Coulombs Law: Opposite charges attract (electrons to protons) Like charges repel (protons repel protons but more importantly electrons repel electrons) Recall that atoms can be viewed as a positively charged nucleus surrounded by a negatively charged electron cloud
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