Bio 118 1st Edition Lecture 3 Outline of Last Lecture a. Electron Arrangement around the nucleusb. Chemical Bondingc. How many bonds can an atom have?d. Electronegativity & chemical bondingOutline of Current Lecture I. Ions and Ionic BondsII. The Electron-Sharing ContinuumIII. Key Properties of WaterIV. Water and Hydrogen BondsV. Correlation of Water’s Structure and PropertiesVI. The Importance of CarbonVII. Functional Groups: Determinants of Chemical BehaviorCurrent LectureIons and Ionic Bonds- Ion: An atom or molecule that carries a charge o Cation: An atom that loses an electron and becomes positively charged ex. Na+o Anion: An atom that gains an electron and becomes negatively charged ex. Cl-- The resulting attraction between oppositely charged ions is an ionic bondo Transfers electrons and gives resulting atoms a full outermost shellThe Electron-sharing Continuum- The degree to which electrons are shared in chemical bonds form a continuum, from equal sharing in nonpolar covalent bonds, to unequal sharing in polar covalent bonds, tothe transfer of electrons in ionic bondsKey Properties of Water- Life is based on water because water is a great solvent agent for dissolving substancesand getting them intoThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- The covalent bonds in water are polar because oxygen has a greater electronegativity than hydrogeno Oxygen has a partial negative chargeo Hydrogen has a partial positive charge o Hydrogen bonds are the weak electrical attractions between the partially negative oxygen of one water molecule and the partially positive hydrogen of a different water moleculeWater and Hydrogen Bonds- Ions and polar molecules stay in solution because of their interactions with water’s partial charges. These atoms and molecules are said to be hydrophilic- Uncharged and nonpolar compounds do not dissolve in water and are said to be hydrophobico Water molecules surrounding nonpolar molecules form hydrogen bonds with one another and increase the stability of these hydrophobic interactions- Hydrogen bonding makes it possible for almost any charged or polar molecule to dissolve in waterCorrelation of Water’s Structure and Properties- Water is unique due to its small size, bent shape, highly polar covalent bonds, and overall polarity. - Water also has several remarkable properties, largely due to its ability to form hydrogen bonds:o Cohesive stays together because of the hydrogen bonds e.g. water becomes a droplet instead of just spreading outo Adhesive water adheres to surfaces that have any polar or charged components E.g. water sticks to the side of a beakero Denser as a solid than a liquid more molecules in volume of liquid water than in same volume of iceo Able to absorb large amounts of energy High specific heat: energy required to raise the temperature of 1 g of substance by 1 degree Celsius The Importance of Carbon- Carbon is the most versatile atom on Earth because it has a valence of 4, carbon can form many covalent bonds- Carbon-containing molecules can form an almost limitless array of molecular shapes with different combinations of single and double bonds- When molecules contain more than one carbon atom, these atoms can be bonded to one another in long chains- The formation of carbon-carbon bonds was an important event in chemical evolution- Check out figure 2.24Functional Groups: Determinants of Chemical Behavior- The carbon atoms in an organic molecule furnish the skeleton that gives the shapeo Amino & carboxyl groups: Attract or drop a proton, respectively. Nitrogen & 2 oxygen NH2 Amino adds, carboxyl drops Amino= amines Carboxyl= carboxylic acidso Carbonyl groups: Sites of reactions that link molecules into larger, more-complex compounds Aldehydes & Ketoneso Hydroxyl groups: Polar group and act as weak acids Alcoholso Phosphate groups: Have 2 negative charges Organic phosphateso Sulfhydryl groups: Link together via disulfide bonds Thiols Disulfide bonds:
View Full Document
Unlocking...