CH 304K 1st EditionExam # 2 Study Guide Lectures: 9-19Lecture 9 (February 9)What is ozone?Ozone is an allotrope of oxygen. While O2 is a colorless, odorless gas, O3 is a colorless, pungent gas. Ozone is made from Oxygen combined with energy. It is continually formed and destroyed in the part of the stratosphere referred to as the Ozone Layer. It is about 15-30 miles above the earth’s surface and protects us from some of the sun’s UV rays.Lecture 10 (February 11) Describe the structure of an atom.Atoms are comprised of protons (+), electrons (-), and neutrons (neutral). In the middle is the tiny, very dense nucleus that contains the protons and neutrons. The diameter of the atom is approximately 10,000-100,000 times greater than the diameter of the nucleus. The atomic number is the number of protons in the element. The atomic mass number is the sum of the protons and the neutrons. Lecture 11 (February 16)What is quantum mechanics?Because you cannot determine exactly where an electron is, quantum mechanics is a way to determine where an electron is likely to be. Electrons move in orbits around the nucleus. Each orbitals have different energy levels; to move to a lower level, they emit a photon, to move to a bigger level, they absorb a photon.Lecture 13 (February 20)What do valence electrons have to do with atomic bonding?When two atoms come together, they form bonds by sharing valence electrons. Valence electrons are the electrons in the outermost level of the atom. Higher bond order means more bonds which means a stronger overall bond. Long bonds have less bonds and are easier to stretch farther apart. Lecture 14 (February 23)What is resonance?Resonance is when more than one Lewis dot structure can be drawn for the same arrangement of atoms; only the bonds differ. The actual structure is a hybrid of many possible resonances.Lecture 15 (February 25)What is important to remember when drawing Lewis dot structures?Write out the formula of the compound, count the number of total valence electrons, draw “skeleton” structure, draw single bonds connecting center atoms to surrounding ones, fill in remaining electrons trying to fill octets, use lone pairs to make double or triple bonds.Lecture 16 (February 26)What are photons and what do they do?Photons are “particles” of light and a bundle of energy. They have NO mass. The energy of a photon= h (Planck’s constant) x frequency. Photons can cause electrons to move to different energy levels, bonds in molecules to move, vibrate, rotate, or even break bonds. Photons of UV have a wavelength of less than 320nm. They have enough energy to break bonds or ionize molecules/atoms (kick out electrons). Both of these are potentially very damaging to cells of thebody. Because they have a short wavelength, they have a great amount of energy.Lecture 17 (March 2)What are some examples of natural ozone destroyers?CFC’s and Halons are ozone destroyers. They have a low chemical reactivity in the troposphere, but are then broken down in the stratosphere by UV and create Chlorine radicals. Chlorine radicals are a catalyst for O3 destroying reactions. Fluorine and chlorine radicals are both found in the stratosphere. There is no natural atmospheric source of fluorine radicals so they all come from CFC’sWhat is the Montreal Protocol?In 1987, the US and 140 other countries began movements to stop the production of CFC’s by the end of 1995. The last use of CFC’s was in medical inhalers which ended in 2008.Lecture 18 (March 4)What are the different types of UV Radiation?UV-A (320-400nm): “black light”; not absorbed by the ozone layer; causes premature skin aging and skin cancerUV-B (280-320nm): mostly absorbed by ozone layer; causes cataracts, skin cancer, crop damage,damages fish eggs and larvaeUV-C (200-280nm): absorbed completely by the ozone layer and oxygen; most damaging to cells; used to sterilize surfaces because it can kill viruses and bacteriaLecture 19 (March 6)How does each kind of light interact with matter?When electrons move between orbitals of different energies, they show visible light (emission or absorption spectra). UV breaks bonds between atoms. Microwaves cause rotation of molecules. Infrared causes vibration which makes structures bend and stretch like springs. Describe the Greenhouse Effect.The atmosphere around the earth absorbs and emits about 80% of the sun’s incident energy to the surface of the Earth. The gases in the atmosphere are responsible for trapping heat in the atmosphere. However, if there is too much of an increase of these gases, it will make the temperature on Earth to rise to an unlivable