Lecture 11 - Coulomb's Law, Lewis Structures I

Thursday, February 15, 2024

1:30 PM

"The beauty of chemistry is that I can design my own molecular world." - ﷟HYPERLINK "https://www.nobelprize.org/prizes/chemistry/1999/press-release/"Ahmed Zewail Class notes can now be found here: https://bricejurban.github.io/CHEM111/ Assignments due this week: ﷟HYPERLINK "https://boisestatecanvas.instructure.com/courses/28699/assignments/990975"HW 5 - Quantum Part 2 (Aktiv Chemistry)(Sun 2/18) New Activity: ﷟HYPERLINK "https://boisestatecanvas.instructure.com/courses/28699/assignments/993257"Emerging Tech in Chemistry Post which technology you're interested in (Fri 2/16) Reading for today's lecture 7.1-7.4, 7.8 Reading for next lecture 7.5-7.10 Office Hours: Friday 11-1 CIC ﷟HYPERLINK "https://calendly.com/bricejurban/office-hours"By appointment Today (2/15) Coulomb's Law Electronegativity Covalent Bonding Lewis Structures Part I Formal Charge Tuesday (2/20) Lewis Structures Part II Coulomb's Law can be used to calculate the energy of an ion pair Untitled picture.png QIQ2 oulomb (231 aJ•pm) The energy of interaction between two ions is directly proportional to the product of their electrical charges and is inversely proportional to the distance between their centers. The proportionality constant is 231 aJ•pm when: The energy is expressed in attojoules (1 x 10-18 J) The distance between the centers is in picometers (1 x 10-12 m) The charges (Q) are measured in units of the charge on a proton (+1, +2, -1, -3 etc) What is the energy of attraction between a sodium ion and a fluoride ion? Untitled picture.emf Charles-Augustin de Coulomb Untitled picture.png Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
What is the energy of attraction between a calcium ion and an oxide ion? Untitled picture.png Untitled picture.png TABLE 6.4 Crystallographic radii of ions in picometers (l pm Ion Radius Cations: Ion Cu24 24 Ni24 Sr24 Z 1124 Radius 135 100 95 65 73 61 72 69 118 74 Ion Gab* In 34 La 34 "I-13* Radius 54 23 62 55 62 80 103 89 90 Ion C e44 Ti4+ 44 = 10-12 m) Radius 87 61 89 84 Ion Radius Ion Tez- Radius 184 198 221 Ion Anions: Radius 171 212 cuv 115 167 77 138 76 102 152 150 196 181 154 220 Untitled picture.png TABLE 6.5 Electron affinities of the atoms of some reactive nonmetals Atom o s EA/aJ —0.12 —0.545 —0.580 —0.540 —0.490 —0.234 +1.30 (EA2) —0.332 +0.980 (EA2) Untitled picture.png TABLE 4.1 Successive ionization energies of the elements hydrogen through sodium* Ionization energy/aJ Z 2 3 4 5 6 7 8 9 10 11 Element He Be c o 2.18 3.94 0.86 1.49 1.33 1.81 2.32 2.17 2.78 3.45 0.83 8.72 12.1 2.92 4.04 3.90 4.75 5.63 5.60 6.56 7.57 19.6 24.7 6.08 7.67 7.60 8.80 10.0 10.2 11.5 34.9 41.5 10.3 12.4 12.4 14.0 15.6 15.8 54.5 62.8 15.7 18.2 18.3 20.2 22.2 16 78.5 88.4 22.7 25.2 25.3 27.6 107 118 29.7 33.2 33.4 140 153 38.3 42.3 177 192 48.0 218 238 264 Useful tables Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Untitled picture.png TABLE 4.1 Successive ionization energies of the elements hydrogen through sodium* Ionization energy/aJ Z 2 3 4 5 6 7 8 9 10 11 Element He Be c o 2.18 3.94 0.86 1.49 1.33 1.81 2.32 2.17 2.78 3.45 0.83 8.72 12.1 2.92 4.04 3.90 4.75 5.63 5.60 6.56 7.57 19.6 24.7 6.08 7.67 7.60 8.80 10.0 10.2 11.5 34.9 41.5 10.3 12.4 12.4 14.0 15.6 15.8 54.5 62.8 15.7 18.2 18.3 20.2 22.2 16 78.5 88.4 22.7 25.2 25.3 27.6 107 118 29.7 33.2 33.4 140 153 38.3 42.3 177 192 48.0 218 238 264 Coulomb's law can be used in conjunction with ionization energies and electron affinities to estimate the energy gained in the formation of an ionic bond. Let's calculate the value of the energy change in aJ per ion pair for this reaction: Na + H → Na+H– Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
The lattice (crystal) energy is Coulomb's law applied to all of the neighboring ions Bond Polarity The difference in strength two atoms have on shared valence electrons In an ionic bond, valence electrons are completely transferred to the anion. In a covalent bond, valence electrons are shared or mostly shared Ionic Bond = Unhappy baby Untitled picture.png Covalent Bond = Tug of war Untitled picture.png ﷟HYPERLINK "https://ptable.com/#Properties/Electronegativity"Electronegativity 𝝌 How chemists quantify bond polarity "The tendency of an atom to attract a shared pair of electrons towards itself". Linus Pauling came up with electronegativity (𝜒) scale based on a geometric averaging of the ionization energy and electron affinities Scale of 0 to 4 Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
What element has the highest tendency to attract electrons? Fluorine Which elements have no EN? Noble (Inert) gases Which of these elements is the least (nonzero) EN? Francium Where does Hydrogen fall in terms of the other elements? Right in the middle (2.1) Untitled picture.png 2.1 g 0.98 11 0.93 87 0.7 2 He 10 4 Be 1.57 12 Mg 1.31 88 0.9 5 2.04 2.55 3.04 3.44 3.98 89+ 1.1-1.3 2.20 2.28 2.54 2.00 2.04 2.33 2.02 2.0 2.2 Figure 7.13 Electronegativities of the elements as calculated by Linus Pauling. Note that the Untitled picture.png > 3.98 3.44 Cl 3.16 > N 3.04 > S 2.58 > C 2.55 > P 2.19 > H 2.1 The most useful electronegativity values Electronegativity differences Δ𝜒 determine bond polarity Type of Bond Example Bonded Elements Nonpolar Covalent Bond Also called Pure Covalent Cl-Cl Δ𝜒<0.4 Strong NM† & Strong NM or Weak NM & Weak NM Polar Covalent Bond H-Cl 0.4≤Δ𝜒≤﷐2.0﷮∗﷯ Weak NM & Strong NM Ionic Bond Na-Cl Δ𝜒>﷐2.0﷮∗﷯ Metal & NM Examples of calculating the polarity of a bond: C - N Na - O Mg - C Br - O (Br 𝜒 = 2.96) N - N S - O P - F Cr - Cl (Cr 𝜒 = 1.66) | 2.55 - 3.04 | = 0.49 Polar Covalent | 0.94 - 3.44 | = 2.50 Ionic | 1.31 - 2.55 | = 1.24 Polar Covalent | 2.96 - 3.44 | = 0.48 Polar Covalent | 3.04 - 3.04 | = 0.00 Nonpolar Covalent | 2.58 - 3.44 | = 0.86 Polar Covalent | 2.19 - 3.98 | = 1.79 Polar Covalent | 1.66 - 3.16 | = 1.50 ? Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Metallic Bond Na-Na Metal and Metal † NM = Non-metal * These are general guidelines. At the extremes, we tend to get a mix of ionic and covalent character (i.e. HF, AlI3) Bond polarities can be indicated with partial charges ﷐𝛿﷮+﷯ means slightly positive. ﷐𝛿﷮−﷯ means slightly negative Cr - Cl (Cr 𝜒 = 1.66) Fe - H (Fe 𝜒 = 1.83) Ca - O (Ca 𝜒 = 1.0) | 1.66 - 3.16 | = 1.50 ? | 1.83 - 2.20 | = 0.37 Nonpolar Covalent | 1.00 - 3.44 | = 2.44 Ionic Note that some metals and nonmetals have significant covalent character and these are just estimates of the bond character. Drawing Covalent Molecular Structures (Lewis Structures) Instead of the transfer of electrons to obtain a noble-gas electronic configuration, in covalent molecules there is a simultaneous sharing of electrons. For example the molecule Cl2: Untitled picture.png Untitled picture.png Untitled picture.png Cl ([Ne]3s23p5) + Cl ([Ne]3s23p5) ⟶ Cl2 ([Ar][Ar]) Both atoms now have a noble gas outer electron configuration of eight electrons. G. N. Lewis generalized this result into what we call the octet rule: each element forms covalent bonds such that eight electrons occupy its outer shell. Unpaired electrons are known as lone pairs. Algorithm for Drawing Lewis Structures Arrange the symbols of the atoms that are bonded together in the molecule next to one another. Compute the total number of valence electrons in the molecule by adding the number of valence electrons for all the atoms in the molecule. If the species is an ion rather than a molecule, then you must take the charge of the ion into account by adding electrons if it is a negative ion or subtracting electrons if it is a positive ion Represent a two-electron covalent bond by placing a line between the Untitled picture.png G. N. Lewis - Introduced Lewis structures and covalent bonds in the 1920s. Tips: The central atom is usually the least electronegative unless hydrogen which is always terminal. Some compounds will not have a central atom, but several. Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Represent a two-electron covalent bond by placing a line between the atoms that are assumed to be bonded to each other Arrange the remaining valence electrons as lone pairs about each atom so that the octet rule is satisfied for each one Check the formal charge on each atom to help with competing structures If there is not enough electrons, you may need to use double bonds, triple bonds or rings or the central atom(s) has a deficient octet or you have a radical If there are too many electrons, you may need to put electron pairs on the central atom and/or form double bonds to reduce formal charges (this will not be assessed in CHEM 101) Draw any valid resonance structures if requested Some compounds will not have a central atom, but several. Be, B, and Al have deficient octets Elements in the 3rd row (S, P . . . )can expand their octet to have 10, 12, or more e-. If the molecule is an ion, bracket the structure and put a charge in the corner Molecules with an odd number of electrons will form a free radical, a reactive species. Examples of Lewis Structures (Steps 1-4 only) OF2 NH2– PCl4+ CHCl3 (chloroform) N2H4 (hydrazine) CH3OH (methanol) Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Assigning Formal Charges help with determining the best structure (Step 5) Sometimes more than one possible structure may be possible. In that case it is necessary to assign a formal charge to the atoms in the structure to help aid us in choosing the correct one. We assume each pair of shared electrons are shared equally and assign one of the electrons to each atom. Lone electron pairs are assigned to the atom they are located on. Use this equation: Untitled picture.png formal charge on an atom In a Lewis formula total number of = valence electrons in the free atom total number of lone-pair electrons total number of shared 2 electrons NH4+ (ammonium) H3O+ (hydronium) OF2 (written as OFF) Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Which structure is preferable for hydroxylamine? NH3O Pick up here next Tuesday NH2OH Which structure is preferable for hydrogen peroxide? H2OO HOOH Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
When there are not enough electrons (Step 6) Some elements are electron deficient are do not require an octet when forming a covalent bond. This is restricted to H, Li, Mg, Be, B, and Al. What is more likely is that you need to use double or triple bonds, especially if there is C or O present. If the molecule is larger, you can also form ring structures to use up 2 electrons. Lastly, if you have an odd number of electrons radical (unpaired electron) compounds are also possible. H2 Li2 BeCl2 MgH2 BH3 AlBr3 C2H6 (ethane) C2H4 (ethene) C2H2 (ethyne)
C6H6 (benzene) C2H3O2– (acetate) CH3• (methyl radical) O2•– (superoxide anion radical) (C6H5)3C• Trityl radical First organic radical discovered. Moses Gomberg in 1900 at University of Michigan (my alma mater)
(superoxide anion radical) When there are too many electrons (Step 7) Some elements allow for an expanded octet when forming covalent bonds. This is restricted to elements in the third shell or higher including the elements: P, S, Cl, As, Se, Te, Br, I, and even Xe. Never will an element such as C, N, O, or F have an expanded octet I will not test on this (unless it is an extra credit problem)  SF6                 XeF2 IF5

 

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