Molecular Polarity

SOB o Name: Molecule Polarity PhET A study of electronegativity, bond polarity, and molecular polarity frftr &c t ncij of c\ v\ Introduction: e' In this atomic-level simulation, you will investigate how atoms' electronegativity value affects the bonds they produce. When two atoms bond, a pair of electrons is J8 shared between atoms. Electronegativity is a measure of a single atom's ability to Molecule Polarity hoard electrons shared in that bond. In this lab you will work diligently, at your own pace, to answer a number of questions. To begin, from what you've already learned about the protons and electrons in an atom, what would cause an atom to have a high electronegativity value ? Wxorg. rVv"> _ =f h nyv ny - - View y Bond Dipote Why might an atom have a low electronegativity value? e y Partial Charges WSs choir 4 kgi CtAxar -UO\A Procedure: 1 Two Atoms - * Bond Character , \ Surface none Turn on (check ) all view options. Take your time and investigate how the binary compound's bond behaves when the Electrostaic Potential Electron Density ft atom ' s electronegativity and orientation are changed. Do not rush through this step. Electric Field ft on off Describe the bond formed between two atoms with similar, low electronegativities. ^ is ooualifryf bond Describe the bond formed between two atoms with similar, high electronegativities. s ^ -SKl 1 is rourxlPA -f- bond Describe the bond formed between two atoms with very different electronegativities. P D I A E- PPDND Describe (in your own words) what is meant by partial charges, 6- nd 6+. 6- represents: C ~ 6+ represents: " AT-g C\ Y-Q ^ i \o Wrote ^l-f ( PVWtrx&a fA -fo + ^ V\ Of -e C OACf ( ( flOlS s /de jp e \MAC What happens when the electric field is applied to a very polar molecule? Why do you think this is? fl What is electron density? pnlflr WTpleCui-g IS A.4 ( A l i Ij l -fp tC\Cy\ OWW T blOlA ) C \ OSg -fhf ' How does the density around a partial positive compare to the density of a partial negative ? i s U s s f\ pv\Q . VYZV + \ What would bring about a higher electron density around an atom? A f: K) V -/ (/U -A A bond is characterized as ionic or covalent by comparing the differences between two atoms' electronegativities. ( ^\-V VQ)escribe an ionic bond in terms of the atoms' electronegativity values. C\ \ CK fgq. - \C\ V\ \ W>, 1 fO . Describe a covalent bond in terms of the atoms' electronegativity values. 0 *=» 1«" u Ps. - ^ £3 M C\Z J iTCPfPftf £ * SUfAilflY" HfO Additionally, we further separate covalent bonds into polar covalent and nonpolar covalent . What would have to be the case for a bond to be nonpolar covalent ? (f rA 0S~f* N / fll U -P S> 0.0- 0* 4r eM - ’ Three Atoms js simiilation realize that in addition to changing |n View the electonegativities, you may also move individual atoms by dragging Z Bond Dipoles Molecular Dipole <=0 iZ them with the mouse. Here, in addition to bond polarity (represented by Partial Charges the bond dipole ), the entire molecule may be polar ( represented by the molecular t dipole ). It is this molecular dipole that determines the polarity of the molecule and Electric Field how it interacts with other molecules and its environment. For instance, molecules * OTi a*f with high molecular dipoles tend to have high intermolecular forces. ( Why?) 1 \ dl fV ^ BTW: The molecular dipole is found using vector addition, adding the bond dipoles together; think a tug - of-war. Take some time and adjust each of the atom's locations and electronegativity values several times. Observe how the bond dipoles (between A-B and B-C) add to produce a molecular dipole. fi How might a molecule with two strong bond dipoles have no molecular dipole at all? Shape frf -tVae moIcnJ-o oiTi How might a molecule have a very strong molecular dipole. u l % a large err # . BK) \ Real Molecules ^fcixe dissolvesJike" is a way to remember that molecules with similar molecular dipoles will tend to interact favorably and mix. For instance, water (H2O) is a polar molecule. It will mix well (dissolve) polar molecules, such as ammonia ( NH3), a mixture often used in household cleaners. Both molecules possess strong molecular dipoles* / A molecule such as methane ( CH4) would not dissolve well into water. Why ? Befpfe' usingxhe simulation , complete the table below ( with a V) to predict whicnoFthe^follQwing should dissolve imo water. Create a Lewls dot dia grg7Trt:6= ^ ^ ^^ ~ guide your thinking, (use.^separalepige ^ Prediction ( before using thepfmulation ) H2 J '2 02 F2 HF * z 7 z AiO coT HCN .aH3 JSR) CH 2O CH4 CH F CH2F2 CH3F CF4 CHCI3 7 V ^ / / Next, use the simulation to determine with of the^species should'dissolve in water. H2 N2 O 2 EzT HE ,H2p C0 HCN 03 BF3 CH2O CH4 CH3F Q/2F2 V ^ / / Finally, what type ofsolven C ould be required to dissolve nonpolar compounds? T CH3F CF4 CHCI3