Chemical Principles - The Chemistry of Life Atoms and...

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Unformatted text preview: The Chemistry of Life: Atoms and Molecules Elements Pure substances that cannot be broken down into simpler chemical entities by ordinary chemical reactions. Periodic Table 112 known elements Major Elements Comprising the Biological Molecules of Living Things Things •Carbon •Hydrogen •Oxygen •Nitrogen •Phosphorus •Sulfur Other Major Elements of Living Things Living • • • • Calcium (Ca) Potassium (K) Chlorine (Cl) Magnesium (Mg) Some Important Trace Elements of Living Things Elements • • • • • • Boron (B) Cobalt (Co) Iron (Fe) Copper (Cu) Fluorine (F) Zinc (Zn) Elements & Atoms An element is composed of atoms (0.1-1 nm in diameter) Atom→ cluster of small particles (proton, neutron, electron) Subatomic Particles Subatomic Protons (p +) Electrons (e -) Neutrons (n o) Electron Shell Configurations of Atoms Electron proton neutron electron hydrogen atom 1p, 0n, 1e- helium atom 2p, 2n, 2e- carbon atom 6p, 6n, 6e- atomic number: number of p; #p = #e- He atomic mass (atomic wt.): sum of masses of p+n He→ 2p + 2n, atomic mass = 4 p+n e- He He Carbon Atom C p= n= e- = Atomic number = Atomic mass = 2 He C p= n= e- = Atomic number = Atomic mass = C Isotope atoms that differ in the number of neutrons C12 stable C13 stable isotope C14 unstable- radioactive isotope Molecule Molecule Two or more atoms held together by chemical bonds Oxygen O Compound Compound Binding two or more different kinds of elements together NaCl CH Ion Ion An atom that has either gained or lost electrons such that it exhibits a net charge Na+ Cl- Sodium (Na) Atom Atom 11 P+ 12 No Sodium (Na ) Ion Sodium + 11 P+ 12 No Chlorine (Cl) Atom Atom 17 P+ 18 No Chloride (Cl ) Ion Chloride _ 17 P+ 18 No Some Examples of Ions Some Hydrogen Potassium Fluoride H K F Complex Ions 2 3 2- Bond Types: Bond • Ionic • Covalent • Hydrogen Ionic Bonds Ionic Transfer of electron 11 P+ 12 No 17 P+ 18 No Covalent Bonding: Covalent electron sharing O H H Covalent Bonding: Covalent electron sharing H H C H H H C H H H Examples of Organic Molecules Molecules Properties of Water Properties 1. High heat capacity-absorbs and releases large amounts of heat (land heats faster than water) 2. High heat of vaporization- sweat, cooling mechanism 3. Polarity solvent propertiesuniversal solvent 4. Reactivity- hydrolysis and condensation (dehydration) Polarity of Water Molecules Molecules Hydrogen Bonding Between Water Molecules Water Hydrogen bond Covalent bond Hydrogen Bonding Between Different Molecules Different Chemical Reactions Chemical A →B reactant → product reactant Chemical Synthesis Chemical A + B → AB Chemical Decomposition Chemical AB → A + B Chemical Rearrangement Rearrangement AB + CD → AC + BD Decomposition of Water Decomposition H2O ⇔ H+ + OH- Acids Acids Proton donor, i.e., they donate H+ ions HCl is a strong acid with a pH 1-2 HCL ⇔ H+ + Cl- Bases Bases Proton acceptor, i.e., they take up H+ ions NaOH is a strong base ~pH 12 Na+ + OH- ⇔ NaOH NH3 + H+ ⇔ NH4 OH - + H+ ⇔ H2O HCO3 +H+ ⇔ H2CO3 NeutralizationHCl + NaOH→ H2O + NaCl Buffer- resists dramatic changes in pH; ex. tums, rolaids…buffers stomach acid pH Scale pH 0-14 Type of pH Value Solution Neutral 7 Acidic 0-6 Basic (alkaline) 8-14 pH Scale pH Logarithmic scale Inquiry ...
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This note was uploaded on 04/19/2011 for the course BIOL 101 taught by Professor Wong during the Fall '09 term at University of Hawaii, Manoa.

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