Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 1 of 18 Honors Chemistry Unit 5B: Covalent Bonding, Nomenclature, VSEPR and Polarity Vocabulary Problem Set Due: Test : VOCABULARY: covalent bonds molecular compound resonance structure molecule empirical formula intermolecular forces polar covalent molecular formula Van der Waals forces nonpolar VSEPR (London) dispersion forces OBJECTIVES: Be able to describe and identify the three types of bonds: ionic, molecular, and metallic. Be able to describe characteristics of ionic, molecular and metallic compounds. Be able to describe the difference between polar and nonpolar molecular bonds. Be able to determine bond type using the periodic table or electronegativity difference Unit 5B EQs: Day 1 – Review If X represents an element from group 2A of the periodic table, what would the formula of its fluoride be? If element M forms the compounds MBr3 and M2S3, element M would be found in which group of the periodic table? Why? According to the graph below, which letter indicates the noble gas? The alkali metals? Why is there such a large difference in ionization potential between them? Day 2 - New Material: What type of bonds are found in the following: a. CH4 c. KCl b. Na3PO4 d. gold bar List the above in order of strongest bond to weakest bond. Day 3 Write the molecular formula for the following: a. diantomony trioxide d. oxygen difluorids b. sulfur hexachloride e. carbon tetrachloride c. tetraphosphorus decoxide f. fluorine monosulfide Write the name for each of the following molecular formulas: a. CO2 d. CO b. NH3 e. BI3 c. P2O5 f. SO3 Day 4 Illustrate the correct structure formula for C2H4. What is a resonance structure? Draw an example of one from your notes. List the 6 main VSEPR shapes and draw an example of each. Day 5 What is the correct molecular shape of CH4? How was this determined? Compare and contrast polar covalent and nonpolar covalent molecules. Give an example of each. Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 2 of 18 BOND IONIC – transfer of electrons (∆ EN) is >1.7 COVALENTSharing of electrons (∆ EN) is <1.7 METALLICFree flow of Electrons Atoms involved Metal & Nonmetal or Metal & polyatomic ion Force Attraction between ions, opposite charges attract Two nonmetals Polar = unequal sharing = partial charge Nonpolar = equal sharing = no charge Two metals Sharing of electrons Sharing of electrons between all atoms Properties High melting point. High boiling point Water soluble Crystalline Aq solutions conduct a current Low melting & boiling point Brittle Nonconductors Examples NaCl MgO CaS K2SO4 (also includes cov bond) Water CO2 NH3 Good conductors. Malleable = shapeable, Ductile = able to be drawn into wire Copper wire Iron bar Relative strength Generally the strongest bond type = the larger the ion charges the stronger the ionic bond. Weakest bond type(exception network solids like diamonds) Strongest: H bond Dipole-dipole Weakest: dispersion forces VSEPR & Molecular Geometry Molecular Shape Linear Bent Type of Molecule Atoms Bonded to Central Atom Lone Pairs of e-s on Central Atom AB2 2 0 2 1 3 0 4 0 3 1 2 2 AB2E 2 surrounding atoms – I pair of lone e-s Trigonal Planar AB3 Tetrahedral AB4 Trigonal Pyramidal AB3E 3 surrounding atoms – I pair of lone e- Bent AB2E2 2 surrounding atoms – 2 pairs of lone e- Covalent Bonding Guided Notes Covalent Bonds: between two (or more) nonmetals A little review…Ionic Bonds Between a _____________________ and a _____________________________________ The metal __________________________________ loses electrons that the nonmetal ____________________. The elements are held together (bonded) by an electrostatic charge, ___________________ attracted to negative. Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 3 of 18 Lewis Dot Diagrams We use dots to represent the number of __________________________ electrons an atom has. Can have up to __________ electrons (dots). A new kind of bond…(Example slides: one fluorine atom bonding with another) By ________________________electrons, both fluorine atoms end up with a full octet of electrons and stable orbitals. Covalent Bonds: A bond in which two atoms _________________ pairs of electrons so that each can achieve stability. Properties of Covalent Compounds Made from 2 or more _______________________________________ Are usually liquids and gases (or solids with ____________________ melting points) Covalent vs. Ionic Compounds Covalent Ionic Chemical formulas called __________________________. Chemical formulas called __________________________. Nonmetal bonds with _____________________________. ________________ bonds with nonmetal. Chemical formula begins with a _____________________. Chemical formula begins with a _____________________. Bonds formed by _____________________ electron pairs. Bonds formed by attraction of positive ________________ to negative ____________________. Chemical formula represents _________________ number of atoms in the compound. Chemical formula represents the lowest whole number ________________ of elements in the compound. Lewis Dot Diagrams Writing Lewis Structures Using the NASL Method: There are no “perfect” methods for writing Lewis structures. The NASL method makes counting electrons and number of bonds (shared electron pairs) easier. You always have to think about te molecule or ion that you are working on. Use the NASL method as a guide. You must makek decisions along the way when a molecule is an exception to the rule of eight. Each letter in NASL designates a specific quantity. I present these to your sequentially: N stands for the number of electrons that will satisfy the rule of eight. For representative elements, EXCEPT, N = 8, H and He N = 2 Be N=4 B N=6 To get N for a molecule or molecular ion, add the N values for all atoms in the molecule. A stands for the number of available electrons, ie, electrons in the valence shell. This is the same as the group no. : IA, IIA, IIIA, IVA, VA, VIA, VIIA, and VIIIA. If you do not know the group number for some reason, write the electron configuration and count up all the electrons in the valence shell. To get A for a molecule or molecular ion, count up the valence electrons for each atom in the molecule and add the charge if it is negative, but subtract the charge if it is positive. Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 4 of 18 S stands for the number of electrons that are shared. S=N–A Divide this number by 2 to the get the number of covalent bonds in the molecule. L stands for the number of electrons that are left over. L=A–S Divide this number by 2 to get the number of lone pairs in the structure. When using this method, always keep the molecule before you. There are exceptions to the rule of eight and you must be conscious of this when using any method for writing Lewis structures. Practice NASL Method : Lewis Structures of Covalent Compounds worksheet Remember: atoms form compounds to create a full ___________________of valence electrons (Example slides: bonding of hydrogen and oxygen to form water) We can use Lewis dot structures to represent covalent compounds! 1. Add up the valence electrons of ______________the atoms in the compound. 2. Write the symbols for the elements and _______________________them with a line(s). a. Least electronegative element goes in the ________________ (for example: carbon). H is __________________ on the outside. b. 3. The other elements usually ___________________the center element. ______________ 2 from the total for each line drawn and arrange the rest of the electrons (dots) in pairs around the ____________________ elements first so that each atom has an octet. (H likes 2. B is happy with ____________.) 4. Check for happiness (_________________________)! Example…NH3, Ammonia N is in group 5A, so it has ________ valence electrons. H is in group 1A, so it has ________ valence electron. The compound NH3 has 1 N and 3 Hs, so 5 + (3 x 1) gives a total of _______ valence electrons for the whole compound. •• H–N–H Subtracting 2 from the total for each line drawn: 8 – 6 = 2 __________________________. H You try… HF H2O H–N–H H N is surrounded by 8 electrons, and each H has 2 electrons. (Each _____________ in the dot structure represents 2 electrons.) F2 Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 5 of 18 Double and Triple Bonds DOUBLE and TRIPLE bonds are formed when atoms share 2 or 3 pairs of electrons to attain a ___________________, noble gas configuration. These bonds are represented with ______________________________ lines in a dot diagram. Example: Nitrogen molecule, N2 1. Count the total number of _________________________ electrons, 5 for each nitrogen atom giving a total of 10. 2. Draw the atoms _________________________ with a line. 3. Then ___________________ 2 for each bond (line). 10 – 2 = 8 remaining. Place the 8 remaining electrons in ________________around the 2 nitrogens. 4. But, the Ns aren’t happy. They only have _________ electrons each. What can we do?? We can share ________________ than one pair. Draw the final N2 structure with a triple bond here: Now each N has _______ electrons and is happy. Let’s try a couple together… (Show your work.) CO2 C2H2 Coordinate Covalent Bonds Formed when one atom contributes _________ bonding electrons so that each atom can achieve a noble gas configuration To represent this type of bond, we use an arrow going ____________ the donor TO the atom who is receiving the electrons. Let’s look at the compound _______________________________________________. O donates a _______________ pair of electrons for sharing, forming a COORDINATE COVALENT BOND and allowing each atom to achieve noble gas configuration. Draw the final structure for CO here: Remember to include the arrow. Resonance Structures Structures that occur when it is possible to write 2 or more _____________________electron dot structures that have the same # of electron pairs for a molecule or an ion. Example O3, Ozone Try NO2 The structures of ions are enclosed in _______________________ with the ________________ written on the outside. Negative ions _____________ electrons to the total count; positive ions take away electrons. Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 6 of 18 Can also classify bonds based on electronegativity - if the electronegativity difference (∆ EN) is <1.7 = covlent bond Find the ∆ EN for the bond formed between O and N Example: Show the bonding that occurs between Cl and F. Example two: H and F – hydrogen is an exception to the octet rule! You try: using Lewis dot diagrams illustrate the bonding that occurs between Br and I. Structural Formula Practice Draw the Lewis dot structure for the following compounds with single bonds: 1) HBr 2) PCl3 3) H2S 4) SCl2 5) PH3 6) CCl2F2 Draw the Lewis dot structures for the following compounds with double or triple bonds: 1) SO3 2) HCN 3) SO2 4) N2 Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 7 of 18 Structural Formulas CS2 BF3 NI3 H2Se Cl2 C2H4 VSEPR Theory V___________________ S____________ E________________ P__________ R__________________ Definition: Because electrons repel, _________________________________________ adjusts so the valence-electron pairs are as far apart as possible. Molecular Shape The shape of a molecule is determined by 2 factors: 1. The number of atoms bonded to the _______________________ atom. Double and triple bonds ________________ change the general shape. 2. The number of __________________________ pairs of electrons on the ___________________ atom. Unshared pairs of electrons on ______________ atoms in the compound don't affect the shape. VSEPR Theory: Predicts 3D shape of molecules. 1. _________________ 2. ___________ 3. trigonal _______________ 4. trigonal__________________ 5. ______________________ 6. trigonal ________________________ 7. _______________________ Linear 2 atoms bonded to the _______________ atom 0 lone _____________ on the central atom. All 2-atom molecules are considered linear. Bent 2 atoms bonded to the central atom 1 or 2 lone pairs on the central atom Notice that the Lewis structure does _______ have to show the bent shape. 2 Examples of Linear Example of Bent Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 8 of 18 Trigonal Planar 3 atoms bonded to the ________________ atom 0 lone pairs on the central atom. Since there are no lone pairs on the central atom, Example of Trigonal Planar the compound is _____________. Trigonal Pyramidal 3 atoms bonded to the __________________ atom 1 lone pair on the central atom The lone pair on the central atom ______________ Example of Trigonal Pyramidal down on the other 3 atoms causing a pyramidal shape. Tetrahedral 4 atoms bonded to the central atom Example of Tetrahedral 0 lone pairs on central atom Trigonal Bipyramidal _______ atoms bonded to the central atom o An _____________________ octet o Possible for p-group elements from ______ or later periods 0 _______ pairs on central atom Octahedral _______ atoms bonded to the central atom o Example of Trigonal Bipyramidal Also an ___________________ octet Example of Octahedral 0 lone pairs on central atom Summary Shape Linear Bent Trigonal Planar Trigonal Pyramidal Tetrahedral Trigonal Bipyramidal Octahedral # of atoms bound to central atom # of lone pairs on central atom Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 9 of 18 Model Building Lab Chemical Formula H2O NH3 CH4 H 2S CCl4 CCl2F2 N2 CO2 Color-coded key: Lewis Structure Sketch of Molecule Shape of Molecule Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 10 of 18 Bond Types 3 Types of Bonds Ionic, Polar Covalent (Molecular), & ___________________________________ (Molecular) Remember Electronegativity? The tendency for an atom to attract electrons to itself in a _____________________. The higher the value, the ______________________ it is at attracting electrons. The difference b/w electronegativity values determines what type of ______________ will be formed. Electronegativity is a scale from __________, Cs, to __________, F. It generally ______________________ across a period and decreases ________________ a group. Why don’t noble gases have a value? _________________________________________________________ Ionic Bonds If the electronegativity difference is ___________________________________, one atom will pull the electron completely ______________ from the other atom. The electrons are _______________ shared. An __________________ bond is formed as + and – attract. Electronegativity of Na is _____________; Cl is _____________. 3.0 – 0.9 = 2.1; difference __________________________, so…Ionic. Polar Covalent Bonds Covalent bonds _____________________ electrons. The shared pairs are pulled, similar to a ____________________________, between the nuclei of the atoms sharing the electrons. If the electronegativity difference is between _____________________________, one side of the bond becomes _______________________more negative and the other side becomes slightly more _____________________. This is a _______________________________________ bond. The electronegativity of H is ___________; Cl is ____________ o Oxygen 3.0 – 2.1 = __________; difference is b/w 0.4 – 2.0, so ________________ covalent. The electronegativity of O is ____________; H is_____________ o 3.5 – 2.1 = ________; difference is b/w 0.4 – 2.0, so _______________ covalent. Nonpolar Covalent Bonds When the atoms have equal pull, causing the electrons to be equally shared, the bond is _________________________________ covalent. Neither side of the bond is even slightly _________________ or negative. The electronegativity difference is b/w ______________________. This is the type of bond that occurs between 2 atoms of the _______________ element. (H 2, O2, Cl2, etc.) The electronegativity of H is 2.1. o 2.1 – 2.1 = _________; difference is b/w 0.0 – 0.4, so ________________________ covalent. Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 11 of 18 Attractions Between Molecules: Van der Waals Forces Weaker than either the ionic or _________________________ bonds that form between atoms in a compound. Responsible for determining if a compound is a liquid, gas, or ________________. 3 basic types from weakest to ______________________________ o (London) _________________________________ forces o Dipole __________________________________ o _________________________________________ London Dispersion Forces ________________________ of all molecular attractions Caused by the motion of electrons producing a temporary ____________ Strength of dispersion forces generally increases as # of electrons in the molecule _______________________. ___________ molecules have these weak attractions Dipole Interaction Occurs when ______________ molecules are attracted to one another. Hydrogen Bonds Occurs b/w molecules in which H is covalently bonded to O, N, or ________ which are very electronegative o Causes __________ polar molecules that are _________________ attracted to each other o Still only has about __________ of the strength of a covalent bond Very Important o Reason ice is less ____________ than water o Reason for the relatively ____________ b.p. of water o Responsible for the double helix of the _________ molecule. Nonpolar or Polar Molecules We now know how to determine if the bond b/w atom and atom in a ____________________ is polar or nonpolar. But…what about the whole _________________________? Draw the Lewis __________________. If the central atom has any unshared pairs, the molecule is _______________. If there are no unshared pairs on the _________________ atom, look at the atoms around the central atom. If they are all the _________________, the molecule is nonpolar. If any one of them is different, the molecule is ________________. (In a 2-atom molecule, if the bond between the 2 atoms is _______________, then the whole molecule is polar.) Dot Structure Polar / Nonpolar Dot Structure H20 HCN CO2 N2 HCl CH3Cl Polar / Nonpolar Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 12 of 18 Polarity Involves sharing electrons (to get an octet = 8 valence e-s) o equal sharing = nonpolar - no charge; this occurs when both elements have the same electronegativity (the attraction to an electron) so this occurs when there is a bond between 2 of the same nonmetal for example N2 – both N have an equal pull on the shared electron pair – so there is no partial charge. o unequal sharing = polar – slight charges; this occurs when the two elements have different electronegativities ie you have two different nonmetals in a covalent bond; the more electronegative element (the one further to the right and up on the PT) pulls more on the shared electrons and has a slightly negative charge – the other element will be slightly positive. Ex: Classify the following as polar or nonpolar bonds: HCl, I 2 You try: classify as polar or nonpolar: F2, NO * There are some special molecular cmpds – called network solids (or network crystals) that contain extensive covalent bonding throughout a network of atoms. These compounds are very hard and brittle and have very high melting points ex: graphite and diamonds These are the strongest bonds! Polarity Practice Draw the Lewis Structure. If the central atom has any unshared pairs, the molecule is polar. If there are no unshared pairs on the central atom, look at the atoms around the central atom. o If they are all the same, the molecule is nonpolar. o If any one of them is different, the molecule is polar. In a 2-atom molecule, if the bond between the 2 atoms is polar (electronegativity difference is greater than 0.4), then the whole molecule is considered polar. Remember, a molecule with more than 2 atoms can have polar bonds between its atoms (based on differences in electronegativity) and still be an overall nonpolar molecule. Molecule H2 BH3 Lewis Structure Geometry (Shape Name) Polar / Nonpolar Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 13 of 18 Molecule Lewis Structure Geometry (Shape Name) Polar / Nonpolar N2 SO2 NH3 CO2 BOND STRENGTHS: o Ionic: Generally the strongest bond type = the larger the ion charges the stronger the ionic bond ie Calcium Chloride, CaCl2 is stronger than potassium chloride KCl because Ca has 2+ charge involves 2 e- transferring and K has a 1+; only 1 e- transferring o Metallic: medium strength between ionic and covalent o Covalent: Weakest bond type- (exception network solids like diamonds- strongest bond type) Ex problem: Classify the following from strongest to weakest bond: Copper wire, carbon dioxide, lithium chloride (LiCl) and aluminum nitride (Al3N2). You try: Rank the following from strongest to weakest bond: Water, potassium iodide (KI), pure gold necklace, and calcium fluoride (CaF2) Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 14 of 18 Review Sheet & Naming Practice Lewis Dot Structures 1. Write the symbols for the elements and connect them with a line. H is always on the outside. The other elements usually surround the center one. 2. Add up the valence electrons of all atoms in the compound. Subtract 2 for each line drawn. 3. Arrange the remaining electrons in pairs around the outer elements first so that each atom has an octet. (H likes 2. B is happy with 6.) 4. Check for happiness (stability)! 5. Change unshared pairs of electrons into extra bonds if necessary. VSEPR Shapes Shape Linear Bent Trigonal Planar Trigonal Pyramidal Tetrahedral Trigonal Bipyramidal Octahedral Atoms Bound to Central Atom 2 2 3 Unshared Pairs on Central Atom 0 1 or 2 0 3 4 5 6 1 0 0 0 Polar or Nonpolar Bonds Type of Bond Nonpolar Covalent (Molecular) Polar Covalent (Molecular) Ionic Difference in Electronegativity Values 0.0 – 0.4 0.5 – 2.0 Greater than 2.0 Polar or Nonpolar Molecule 1. Draw the Lewis Structure. 2. If the central atom has any unshared pairs, the molecule is polar. 3. If there are no unshared pairs on the central atom, look at the atoms around the central atom. a. If they are all the same, the molecule is nonpolar. b. If any one of them is different, the molecule is polar. 4. In a 2-atom molecule, if the bond between the 2 atoms is polar (electronegativity difference is greater than 0.4) then the whole molecule is considered polar. Naming Molecular Compounds First, is the compound molecular? o If the first element is a nonmetal, then the compound is molecular. DO NOT USE CHARGES!!! DO NOT SIMPLIFY!!! Use PREFIXES to show how many of both elements! Don’t write mono- on first element. First element keeps its name; 2nd element ends in –ide. 1- mono 2- di 3- tri 4- tetra 5- penta 6- hexa 7- hepta 8- octa 9- nona 10- deca Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 15 of 18 Molecular Naming Practice Write the Formula Write the Name 1) diantimony trioxide ________________________ 1) CO2 __________________________________ 2) carbon monoxide _________________________ 2) CI4 __________________________________ 3) oxygen difluoride _________________________ 3) P2O3 _________________________________ 4) sulfur hexachloride _______________________ 4) N2O3 _________________________________ 5) sulfur tetraiodide _________________________ 5) Cl2O7 ________________________________ 6) dicarbon octafluoride ______________________ 6) BI3 ___________________________________ 7) dichlorine heptaoxide _____________________ 7) S2Cl4 _________________________________ 8) tetraphosphorus decaoxide _________________ 8) NO ___________________________________ 9) pentaphosphorus nonachloride ______________ 9) CS2 ___________________________________ 10) sulfur trioxide __________________________ 10) I2O5 _________________________________ 11) dihydrogen tribromide ___________________ 11) N2O4 ________________________________ 12) nitrogen trisulfide _______________________ 12) SiBr4 ________________________________ 13) heptachlorine monophosphide _____________ 13) P6F9 _________________________________ 14) fluorine monosulfide ____________________ 14) Br2Cl _________________________________ 15) hexabromine dinitride ___________________ 15) I8P ___________________________________ Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 16 of 18 Bonding Basics Review Element Atomic symbol Total # of Electrons # of Valence Electrons # of Electrons Gained or Lost Oxidation Number (charge) Bromine Lithium Calcium Sulfur Boron Silicon Phosphorus 2. Ionic Bonds - Draw the Lewis dot diagrams for each atom, draw arrows to show the transfer of electrons, write the charge for each ion, and then write the chemical formula. We will do A together! (A) Potassium + sulfur (B) Magnesium + Oxygen (C) Lithium + Nitrogen 3. Covalent Bonds – Draw the Lewis structures for each atom, draw lines to show the electrons that are shared, and then write the chemical formula. (A) Fluorine + Fluorine (B) 3 Hydrogen + 1 Phosphorus (C) 2 Hydrogen + 1 Sulfur Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 17 of 18 Properties of ionic, covalent and metallic bonds: Strongest bond type: __________________ remember this involves a transfer of electrons. Because this is the strongest bond type: ionic compounds tend to have: _______________ melting points and boiling points (it takes more energy for these compounds to change states of matter). Are ______________________ - they will break down into ions in water and will conduct an electric current. Ionic compounds tend to be brittle. Weakest bond type: __________________ remember this involves sharing electrons. Because this is the weakest bond type: covalent bonds tend to have: _______________________ melting points and boiling points (it requires less energy for these compounds to change states of matter). Are ______________ - they will not conduct an electric current in water. Covalent bonds may be polar (unequal sharing – partial charges) or nonpolar (equal sharing – no charges). Review on Bonding Fill in the table to the right. Bond Type Type of atoms One Property One example 2. Explain why the oxidation number of Magnesium is 2+ in ionic compounds (It is recommended you use an electron configuration diagram in your explanation) For the following use: 3. KBr C) Covalent Bond I) Ionic Bond M) Metallic Bond 4. Copper wire 5. NaCl 6. NH3 7. Br2 8. Which of the above would have the highest boiling point(s)? 9. Which of the above have the weakest bonds? 10. which of the above is soluble in water? 11. Which of the above is nonpolar covalent? 12. Which of the above is polar covalent? 13. Which of the above would be malleable and ductile? Answers: 1. Refer to Pg 1 with exact same table! 2. Mg electron configuration = 1s2 2s2 2p6 3s2 – has 2 valence electrons – can gain 6 e-s or lose 2 e-s to have 8 (octet rule = 8 e-s full outer level = very stable) Mg will lose its 2 val electrons resulting in a positive 2 charge. 3. I 4. M 5. I 6C 7C 8 KBr and NaCl ionic 9. NH3 and Br2 – covalent 10. KBr and NaCl – ionic 11. Br2 12. NH3 13. Cu wire Covalent Bonding/Nomenclature/VSEPR/Polarity Packet Page 18 of 18 Problem Set- Show all work 1. What is the wavelength and energy type when a Hydrogen atom jumps from n = 5 to n = 3? Is Energy released or absorbed? Wavelength:_________________ Energy type:________________ E released or absorbed:________________ 2. We are taking a class field trip to Europe to practice the factor-label conversion method. For each question show your work and include all units. a. You are filling out the passport application using a pencil containing lead 0.7 mm in diameter. What is the diameter in cm? ____________ b. The class is flying from GSO to London. If the trip is 3200 miles, what is the distance in km? ____________ c. In meters? ____________ 3. Describe the 3 intermolecular forces (IMFs), include their relative strengths. 4. Why would sugar (C12H22O11) melt before salt (NaCl)? 5. Write the Lewis Structures for each of the following. Identify as polar or nonpolar. a. water c. sulfuric acid b. ammonia d. carbon tetrachloride