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This 3 page Class Notes was uploaded by Tobin Durgan on Friday September 18, 2015. The Class Notes belongs to EES 4200 at University of Florida taught by Angela Lindner in Fall. Since its upload, it has received 10 views. For similar materials see /class/206955/ees-4200-university-of-florida in Environmental Science at University of Florida.
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Date Created: 09/18/15
Study Sheet for EES 4200 Exam 1 January 29 2002 Exam Date 2502 Introduction This exam covers material in Chapter 1 of your Ouellette textbook and Lecture 1 in your coursepack notes You will have 55 minutes to complete the exam You will be provided all information necessary to answer questions on this exam eg the Periodic Table You will also be provided spare paper if needed Please bring with you a pencil and eraser no pens please and a calculator To study for this exam please refer to problems in your textbook homework problems problems in the course notes and any additional sample problems handed out or that you may find Please make certain that you understand each of the concepts belowi ATOMS AND ELECTRONS I Know what the atomic number signifies I Understand atomic orbitals in terms of their size shape and spatial orientation I Be able to draw the electronic configuration of any element I Know what the Pauli Exclusion Principle Hund s rule and Aufbau principle signify I Know the difference between electronegativity and electropositivity Know the definitions of ionization potential and electron affinity I Know how atomic properties namely atomic radius electronegativity electropositvity ionization potential electron affinity vary with location on the Periodic Table I What is the significance of valence electrons BONDSLEWIS STRUCTURES I Be able to differentiate between an ionic and a covalent bond and an ionic compound and covalent compound I Know how to draw Lewis structures for any molecule provided you I Be able to calculate the formal charge on any atom in a molecule STRUCTURAL REPRE SE NTATI CNSFUNCTIONAL GROUPS I Know the various ways to present a molecule ie molecular formula structural formula bondline formulas Newman proj ections etc I Be able to calculate molecular formulas given molecular structures I Be able to identify a compound s class by observing its functional groups For example in what class of compounds does the following compound belong HsC39O39CHzCHs ISONIERS I What is the difference between a constitutional isomer and stereoisomer I What are the 3 types of constitutional isomers I Be able to look at different molecular formulas or structures and determine whether they are constitutional isomers and if so what type MOLECULAR SHAPES I Be able to apply the VSEPR theory to determine molecular shapes I Know the basic shapes of simple molecules such as water boron trifluoride and others like them I Know how molecular shape affects molecular properties particularly in terms of polarity of a molecule Be able to predict relative bond moments and dipole moments for bonds and molecules respectively Study Sheet for EES 4200 Exam 1 January 29 2002 Exam Date 2502 IS THE BOND IONIC OR COVALENT As you know from The Tebeook an ionic bond resulTs from The quotTransferquot of an elecTron whereas a covalenT bond resulTs from The IIsharingII of elecTrons WhaT does ThaT really mean IONIC BONDS The Term ionic bond describes The elecTrosTaTic aTTracTion of Two opposiTely charged ions in a crysTalline laTTice One componenT eg Na Ca Mg oTher meTals of The ionic bond musT be elecToposiTive eager To quotlosequot an elecTron To anoTher componenT so ThaT iT has an elecTron configuraTion like iTs nearesT noble gas The oTher componenT eg Cl F eTc wanTs To quotgainquot an elecTron To also be likes iTs more sTable nearesT noble gas So ThaT The elecTrosTaTic aTTracTion beTween The Two is caused by This need To lose or gain an elecTron When Na and Cl come TogeTher They do noT share The elecTron The Na liTerally Transfers iTs elecTron To Cl yielding Na Cl showing The Transfer of The elecTron has occurred There is a very TheoreTical explanaTion for This noT usually covered in inTroducTory chemisTry classes such as This one This deals wiTh Thermodynamics here we go again All of The TransformaTions ThaT Na and Cl can do alone form Na by loss of an elecTron form F by IIsTealingII an elecTron from somewhere eTc involve MORE energy Than by The Two simply associaTing wiTh each oTher To form NaCl solid So ThaT39s whaT They do This Thermodynamic explanaTion is The classical definiTion of an ionic compound However an easier explanaTion is ThaT ionic bonds almosT always involve a METAL on The lefT side of The periodic Table and DO NOT include H as a meTal PLEASE and a NONMETAL on The righT side of The periodic Table COVALENT BONDS These bonds involve The sharing of elecTrons WhaT does This really mean Well EACH aTom is more sTable by sharing The elecTron raTher Than one aTom giving iT up To anoTher LiTerally The elecTrons are IIshuTTledII To and from The Two aToms ThaT are bonded jusT as we began To discuss in class Today They almosT always involve only NONMETALS A poTenTially confusing example of a covalenT bond is HF You may Think ThaT since H is elecTroposiTive and F is elecTronegaTive ThaT This is an ionic bond If you sTudy This molecule closely you will see ThaT iT is noT represenTed as HF as an ionic compound would The elecTron ThaT H has and The elecTron ThaT F has is liTerally shared beTween The Two in an sp3 s bond configuraTion as conTribuTed by The 1s elecTron from hydrogen and The 1 sp3 elecTron from F This is a sigma bond MOST of The organic molecules ThaT you will encounTer in organic chemisTry are covalenT IT is very safe for you To use The rule There are excepTions however ThaT compounds wiTh meTals involve ionic bonding Those wiThouT meTals involve covalenT bonding Study Sheet for EES 4200 Exam 1 January 29 2002 Exam Date 2502 SAMPLE QUE STIONS These are NOT intended to be all inclusive 1 Predict the shape and bond angles of the BR molecule What type of hybridization does it possess 2 Give the electronic configurations for the following atomsi a Ca b 8392 c Kt 3 Many of you have asked is it possible for a 2nd39row atom to NOT contain its octet of electrons I provided you wishy39washy answers of in chemistry there are always exceptions and yes but these structures are not very stable etc Indeed these species DO exist and are very important in atmospheric chemistry A species atoms or molecules that does not have its octet or as a better way to say it has an odd number of electrons is known as a free radical These species typically catalyze atmospheric reactions called free radical reactions such as ozone depletion because of their desire to scavenge electrons from other species such as ozone Os We specify these species by placing a dot I at the end of the species formula The choice of atom to which the unpaired electron is to be assigned in deducing the Lewis structure is obvious from the atomatom connections a Draw the Lewis structures of the following free radicalsi i OH a hydroxyl radical can be formed by ii HsCOO a carboxy radical iii CFzCl a chlorofluorocarbon radical b Calculate the formal charges on each atom of the radicals above What is the total charge of each c How does the Lewis structure for OH39 differ from that for OH 7 4 Here is an example of how a species can have more than one resonance structure In the next section we will learn to draw resonance structures For this exam be able to calculate the formal charge of each atom as well as draw the Lewis structure Br CH CH2 5 The environment in Florida has provided many hidden clues to the effects of some chemicals on the health of humans and wildlife One class of compounds that has been extensively studied at UF are called environmental estrogens These compounds mimic hormones in the body and may ultimately lead to potential developmental problems One example of such a chemical is DDT It was spilled into Lake Apopka and Dr Louis Guilette here at UF found that very few alligator eggs were hatching and those that did hatch had abnormal reproductive systems Provide the expected geometry and angle of the C39C39Cl and aromatic C39C39aromatic C bonds in DDT Write the molecular formula for this compound