micro notes - Chapter 2 The chemistry of biology Atoms:...

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Chapter 2 The chemistry of biology Atoms: Building blocks of molecules Subatomic particles -shell: electrons (e) rotate about the nucleus in their orbitals -Nucleus: *Protons(+charged) *Neutrons Atoms do not carry charge Electron orbitals and Shells Electron rotate around the nucleus in orbitals(pathways) Low level energy electrons: nearest to nucleus: 1 st shell -1 orbital(2e),2 nd shell-4 orbitals(up to 8e),3 rd shell-9 orbitals (up to 18e) Elements: each elements contains characteristics number of electron-position in the table.*there are 115 known elements. Biologically important atoms: 11 elements are biologically important. Hydrogen Carbon Oxygen Sodium Magnesium Phosphorus Sulfur Potassium Calcium Iron Iodine . Isotopes: have different # of neutrons;same physical properties. have unstable nuclei-emit energy-radiactivity significance in biology:1 reactions 2)diagnostic purposes 3)sterilization(gamma irradiation) Radioactivity: *Discovered in 1896 by French scientist Henry Becquerel-mysterious rays(uranium salt blackened the photographic plate) *Decay of unstable,radioactive atoms to form lighter atoms *Emission of the fastest-moving particles( Alpha,Beta) and high energy waves (Gamma)-harmful to living organisms.*study by Marie Curie. Marie Curie 1867- 1934 in Warsaw,Poland : 1) Pioneered research on radioactivity 2)theory of radioactivity 3)discovered 2 elements: Pollium and Radium 4)first female professor @ University of Paris. The first woman to win a Nobel prize: -a)1 st Nobel Prize-in physics (Pierre Curie and Henri Becquerel) b)NP in Chem. Molecules: * two or more atoms combined form a molecule-a new characteristics. compound are formed whenatoms share,donate,or lose electrons. Number of electron in outer shell-valence determines the readiness of an element to react with other element. How the atoms bind together :Through the chemicals bonds: covalent bonds ionic bonds hydrogen bonds. Covalent bonds: bonds between atoms that share electrons.Electrons are not share equally- change of polarity. Ionic bonds: electrons are transferred from one atom to another.when valences complement each other.Ex: NaCl Ionization: dissociation of molecules(atoms into charged particles:cations(+) anions(-)
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when added to water,crystals of NaCL get ionized –Na + Cl - Electrolytes – conduct electricity :acids,bases,salts Each ion becomes hydrated-surrounded by water molecules.hydropholic molecule attracts water(Nacl) *hydrophobic molecules repel water(benzene-a non polar molecule) Hydrogen bonds:Attractive forces between nearby molecules.Ex: water molecules;proteins and DNA.Represnted with dotted line. Chemical formulas: atomic symbols and number of atoms in a molecule : H
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This note was uploaded on 12/13/2011 for the course BIO 0019 taught by Professor Spencer during the Fall '11 term at Broward College.

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micro notes - Chapter 2 The chemistry of biology Atoms:...

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