Lecture 3Outline of Last LectureI. What you should Be Able to do at the End of this ChapterII. Quick Summary of What You Need to KnowIII. The Properties of an Element Depend on the Structure of its AtomsIV. Electrons Determine the Chemical Reactivity of an AtomV. Electron Transfer and Ionic BondingVI. Polar Covalent Bonds in a Water MoleculeOutline of Current LectureI. Hydrogen Bonding: Between MoleculesII. Amazing Property I: Water Sticks to ItselfIII. Amazing Property II: Water Expands on FreezingIV. Amazing Property III: Modulation of TemperatureV. Amazing Property IV: Water is an Excellent SolventVI. Water Can Spontaneously Break into Ions: (H+ and OH-)VII. The pH scale and pH Values of Some Aqueous SolutionsCurrent LectureI. Hydrogen Bonding: Between MoleculesBecause electrons are shared unequally, water is partially positive and partially negative,so it can make hydrogen bonds between other molecules. The more hydrogen bonds that are taking place in a small area, the stronger the bonds are.II. Amazing Property I: Water Sticks to ItselfWater molecules are Cohesive and Adhesive. They form hydrogen bonds with other water molecules and form hydrogen bonds with polar surfaces.III. Amazing Property II: Water Expands on FreezingThese 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. BIOL 101 1st EditionIt is important to know that ice is less dense than water. The hydrogen bonds expand when water is crystalized and turned into ice, allowing it to float on top of and insulating the water beneath it.IV. Amazing Property III: Modulation of TemperatureWater has unusual qualities in temperature when compared to other molecules. It has the high freezing point of 32 degrees Fahrenheit, and high boiling point of 212 degrees Fahrenheit. It is good to note that this is a large span of temperature, and that most water exists as liquid on Earth. In order to rise in temperature, water must take in huge amounts ofenergy before it changes. This is called high specific heat.V. Amazing Property IV: Water is an Excellent SolventBecause water is partially negative and partially positive, its hydrogen bonds can pull apart relatively weak ionic bonds. The positive hydrogens pull in any negative ions in a molecule and the negative oxygen pulls in any positive molecules, thus dissolving the molecule.VI. Water Can Spontaneously Break Into Ions: (H+ and OH-)Hydrogen bonds are weak, and water molecules are always in motion. Occasionally the hydrogens associated with a specific oxygen ion will switch out and be attracted to another oxygen ion, possibly making Hydronium (H3O). Or a water molecule will lose a hydrogen proton to another oxygen and be left as Hydroxide (OH-). Water has a neutral pH level (7).VII. The pH Scale and pH Values of Some Aqueous SolutionsIf something has a pH from 0 to 6, it is an acid. If something has a pH of 8 – 14, it is a base. If something has a pH of 7, it is neutral: neither acid nor base. Specifically, acids add H+to a solution, making it acidic. Bases accept H+ ions or release OH- ions into a solution. A buffer is a solution that is extremely stable at its pH level. It readily accepts or donates H+ or OH- ions to remain at its pH level. PH levels can’t be below zero, or above 14, and each level of pH is a dramatic difference from the next or previous level.These 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. BIOL 101 1st
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