1- basic molecular structure1 chapter 2: the nature of molecules topics you are not responsible for:...
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1- Basic Molecular Structure 1
Chapter 2:The Nature of Molecules
Topics you are not responsible for:molar concentration
End of Chapter questions:Understand: allApply: allSynthesize: 1 & 3
Do all mQuiz Questions
1- Basic Molecular Structure 2
What is PET (Positron Emission Tomography)?
What is it used for?cancerheart diseasebrain function
How does it work?Cell metabolic activityFDG (2-Deoxy-2-[18F]fluoro-D-Glucose)
How is the image created?
PET Image from PetNet solutionshttp://www.petscaninfo.com/zportal/portals/pat
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What is the basic structure of atoms?
Where is energy held in an atom?
Nuclear
Electrons
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What does an electron ‘orbital’ diagram depict?
What does an electron ‘energy level’ diagram depict?
-- electron shells-- “valence shell”
Why are orbitals and energy levels Important to chemical reactivity?
Orbital overlap
‘Octet rule’
Helium Nitrogen
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Why are some atoms radioactive?
What is an isotope?
Unstable isotopes will ‘decay’-- gamma rays-- beta particles-- positrons
Rate of decay as ‘half-life’18F ~ 2 hours32P ~ 14 days
3H ~ 12 years14C ~ 5,760 years
239Pu ~ 24,000 years
Number of: Protons 6 6Neutrons 6 8Electrons 6 6
12C 14C
Shorthand 12C
Animation
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What are the principal types of molecular bonds?
CovalentIonicHydrogenvan der Waals
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What are covalent bonds?
How do they form? -- e- shared to stabilize octet -- orbital orientation
Where are they found?
1- Basic Molecular Structure
Why do atoms form ‘polar’ vs non-polar covalent bonds?
Electronegativity reflects the tendency to donate, share or ‘grab’ electrons
Atoms may differ in electronegativity
In general…If Δ < ~0.8 = nonpolarIf Δ ~ 1 - 2 = polar atoms have partial (δ) charges
What if Δ is > 2?
H2.2Li Be B C N O F
0.98 1.57 2.04 2.55 3.04 3.44 3.98Na Mg Al Si P S Cl
0.93 1.31 1.61 1.9 2.19 2.58 3.16K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
0.82 1 1.36 1.54 1.63 1.66 1.55 1.83 1.88 1.91 2 1.65 1.81 2.01 2.18 2.55 2.96Rb Sr Y Zr Nb Mo Te Ru Rh Pd Ag Cd In Sn Sb Te I
0.82 0.95 1.22 1.33 1.6 2.16 1.9 2.2 2.28 2.2 1.93 1.69 1.78 1.96 2.05 2.1 2.66Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At
0.79 0.89 1.1 1.3 1.5 2.36 1.9 2.2 2.2 2.28 2.54 2 2.04 2.33 2.02 2 2.2
δ+ δ—
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What are ionic bonds?
How do ‘ions’ form?
-- Large Δ in electronegativity-- loss or gain of e- = Oxidation and reduction -- yields Octet stabilization
Ions have full + or – charge
Na +
O2-
Ca2+
polar cov ionic
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What are hydrogen bonds?
How do they form?
Where are they found?
van der Waals bonds-- due to weaker charge fluctuations
Hydrogen bonds image from Michael Muller’s web page athttp://www.uic.edu/classes/bios/
bios100/indexf04am.htm
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How do properties of water influence cellular properties?
-- there is abundant Hydrogen bonding
“Stickiness”cohesion & adhesion
High solubility
Temperature change moderation“Specific heat”
Salt in water
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What determines the ‘pH’ of water?
What is pH?
pH = -Log [H+]
Scale is logrithmic
Water ionizes
H2O ↔ H+ + OH-
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Why is pH important to molecules and cells?-- Properties of proteins-- Enzyme activity
Hemoglobin and the “Bohr Effect”Decreasing pH lowers affinity for O2
Why hemoglobin binds O2 in lungs and releases it in tissues?
How does exercise increase O2 release in tissues?
Hydrolytic enzymes and the lysosomeEnzymes destroy proteins, lipids, etc.
-- produced in Golgi apparatus (pH 7.5)-- transported to lysosome (pH 5.5)
What would be the consequence if hydrolytic enzymes had a pH optimum of 5.5?