Slide 1OrganizationSlide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Planetary Models of ElementsSlide 17Slide 18Slide 19Slide 20Why Do Elements React?Single Covalent BondSlide 23Slide 24Slide 25Anions and CationsSlide 27Slide 28Slide 29Hydrogen Bonding in WaterHydrogen BondsWaterDNA and its H-BondsSlide 34Acids, Bases and pHSlide 36Slide 37pH ScaleAn Example of HomeostasisSlide 41Slide 42Slide 43Slide 44Slide 45Organization Atom: CarbonMolecule: Myoglobin (a protein)Cells: Muscle CellTissues: homogenous layer of cells. One being smooth muscle which is composed of layers of smooth muscle cells. Organ: Different tissues working together to serve a similar function.Smooth muscle, epithelial and connective tissues…make up blood vessel (an organ)System; blood vessels along w/ heart -Circulatory System (ORGAN SYSTEM LEVEL)Organism: Cardiovascular System, Respiratory, Skeletal etc.Atoms are electrically neutralProtons = ElectronsAtomic number = number of protonsAtomic mass = protons + neutronsAtoms:Positively charged protons and unchargedneutrons held by “strong forces” into a centralnucleus around which negatively chargedelectrons occupy orbital shells.Chemical symbols of biologically importantatoms:Ccarbon S sulferHhydrogenCa calciumOoxygen Fe ironPphosphorousMg magnesiumKpotassium Na sodiumIiodine Cl chlorineNnitrogenElectrons:imagined as orbitals at fixed velocities and fixeddistances from the nucleus.the distance from the nucleus defines the“potential energy” level the electron.If the distance is increased, it is done byincreasing the energy of the electron, thusputting it into a higher orbital.Decreasing the energy of the electron will“drop” it to a lower energy level, or a closerorbit around the nucleus.hv d d’ aIn figure a , light energy is converted tochemical energy by transferring to the electronand raising it to a higher orbital (or a higherenergy level)Arrangement of electrons:Orbital:Volume of space where electron is to befound 90% of the time. 18 8 21st shell holds 2 electrons2nd shell holds 8 electrons3rd shell holds 18 electronsThe last shell can only hold 8 electronsIt cannot fill to 18 unless there is an outer (4th) shell- rare inbiological systemsWhen all the orbitals are filled the orbital isstable and non-reactiveHelium = 2 electrons Neon = 10 electronsStable orbital shellsWhen orbitals are partially filled, they areunstable and reactiveIf the orbital is half full, it tends to shareelectrons with other atoms and form covalentbondsCovalent bonds are very strong bonds - difficultto breakhydrogen 1carbon 6Planetary Models of Elementsp+ represents protons, no represents neutronsChemically inert—full outer shellChemically reactive—outer shell not fullnitrogen 7oxygen 8Why Do Elements React?Most elements react because they are highly UNSTABLE due to the fact that their outer electron shell or “valence shell” is not full.Bonding, either by transference of electrons or sharing results in a full outer shell…and a new compound.One column of elements ….The NOBLE gases, do not react..are inert , because their valence shells are already full.Single Covalent BondOne pair of electrons are sharedIf the orbital is mostly full, it has a tendency togain electronsIf the orbital is mostly empty, it has a tendencyto lose electronsAtoms of this discription form ionic bonds.ionic bonds.strong bonds. (but not as strong as covalent bonds)magnetic charge attractions - will dissociate inwater to form ions8 2 8 2 sodium 11 chlorine 17Anion Anion •atom that gained electrons (net negative atom that gained electrons (net negative charge)charge)CationCation•atom that lost an electron (net positive atom that lost an electron (net positive charge)charge)Ions with opposite charges are attracted Ions with opposite charges are attracted to each otherto each otherAnions and CationsChemical Bonds:- covalentshared electrons- ionic strong magnetic attractions- hydrogenweak magnetic attractionsusually between two separatemoleculesWater: A molecular dipole (-) (+) H O H (+)H O H O H O H O H H H H H O H H O HHydrogen Bonding in WaterHydrogen BondsThis is bond between molecules….. OR Between different parts of one moleculeIt occurs between covalently positively charged Hydrogen and negatively charged atom. Important in many biological molecules ……like DNA!!!WaterHigh Specific Heat- Loses and gains heats S-L-O-W-L-YHigh Surface Tension and Cohesion- Water molecules sticking together form a “film” or tension. Universal Solvent- Dissolves polar or ionic molecules which are the most prevalent kind in living systems.DNA and its H-BondsOrganic compounds Inorganic Compounds carbon-based not carbon-basedlipids watercarbohydrates acids & basesproteins saltsnucleotides buffersAcids, Bases and pHAn acid is proton donor (releases H+ ions)A base is proton acceptor (accepts H+ ions)pH = the concentration of H+ ions in solutiona pH of less than 7 is acidic solutiona pH of greater than 7 is basic solutiona pH of 7.0 is neutral pHPURE Water is a neutral molecule; It has as many H+ as 0H- ions. pH = 7One unit in pH change = a 10 fold increase either way in H+ ion conc.  If pH goes up - then you have decrease H+ ion conc. Tenfold and you now are more basic (example.. pH 7 to pH 8 has 10x less H+)pHNegative logarithm of hydrogen ion concentration0 147acid basic alkaline strong weak strongpH ScaleAcids and bases neutralize each otherH+ from acids+ [OH]- from basesH2OBuffers• prevent abrupt pH changes• act as H+ spongeAn Example of HomeostasisNearly all life chemistry occurs around pH 7…slightly over. Blood has pH between 7.3 and 7.5 and must be maintained as such!When pH falls ACIDOSIS, TOO HIGH ALKALOSISBUFFERS: these are what MAINTAIN homeostasis of pH. ….we have buffer systems….Hemoglobin is a buffer.Bicarbonate is an alkaline and a vital component of the pH buffering system of the body ,maintaining acid-base homeostasis. 70%-75% of CO2 in the body is converted into carbonic acid (H2CO3), which can quickly turn into