Chapter 2 and 3

Chapter 2 and 3 - 8/27/2008 1 2 1 2 Overview of Chemistry &...

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8/27/2008 1 Overview of Chemical Elements in the Body (Table 2-1) Major elements : ~ 99.3% Oxygen Carbon Hydrogen Nitrogen Minor elements : ~ 0.7% Calcium Phosphorus Chlorine Magnesium Potassium Sodium Sulfur Atomic Structure Nucleus protons (+ve) + neutrons (0) weight of protons ~ weight of neutrons Electrons: -ve charged particles in orbitals determine how the atom will react chemically # Protons = # Electrons overall an atom is electrically neutral Properties of Atoms Atomic # = # of protons Atomic mass (wt.)= wt. protons + wt. neutrons The Hydrogen (H) atom is the simplest atom with only 1 proton, 1 electron, & NO neutrons Isotopes Multiple forms of the same atom having the same # of protons & electrons, but differ in the # of neutrons Ions Atoms which gain or lose an electron If an atom loses an electron + vely charged ion CATIONS = +vely charge ions, e.g. sodium ion (Na + ) calcium ion= (Ca ++ ) If an atom gains an electron - vely charged ion ANIONS = -vely charged ions, e.g. chloride ion (Cl - ) carbonate ion (HCO 3 - ) Ions have the ability to conduct electricity when dissolved in water (i.e. electrolytes) Molecule: 2 or more atoms unite may be same (e.g. O 2 ) or different (H 2 O) Compounds: 2 or more differentelements unite e.g. H 2 O, CO 2 , CH 4 Chemical Bonds 1 2 1 2 3 4 5 6 7 8 9
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8/27/2008 2 Forces of attraction that hold atoms together Ionic Bonds electron transfer Covalent Bonds electron sharing Hydrogen Bonds weak bonds Ionic Bonds Electron are transferred completely from one atom to another Opposing charges hold the atoms together Covalent Bonds Covalent Bonds Nonpolar: Molecules have a uniform distribution of charges Strongest chemical bonds e.g. lipids Hydrophobic Polar: One atom attracts the e - more than the other atom Does not have a net electric charge, e.g. H 2 O, sucrose Hydrophilic Hydrogen Bonds Weak, but important bonds An intermolecular force, not an intramolecular force, i.e. DO NOT bind atoms into molecules but hold molecules together Give large molecules their shape Water Universal solvent Main transport medium for gases & nutrients Necessary in metabolic reactions Body has ~ 40 liters (10.56 gallons) of body water % of body water as the amount of fat & age babies: 75% water men: 63 % women: 52% Affinity to Water Hydrophilic compounds: “water - loving” WILL dissolve in water ionic Hydrophobic compounds: “water - fearing” WIIL NOT dissolve in water nonpolar molecules ( e.g. lipids) Amphipathic Molecules e.g. Phospholipids
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This note was uploaded on 10/07/2008 for the course HP 320 taught by Professor Islam during the Fall '08 term at USC.

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Chapter 2 and 3 - 8/27/2008 1 2 1 2 Overview of Chemistry &...

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