1 H C C O HHHHH S FFFFS FFFF H O HReview: Lewis Structures, Shapes, Hybrid Orbitals Fill in the table. Consult the textbook for the rules used to draw Lewis structures Brief summary of the rules: 1. Count the total number of valence electrons in the structure. If the structure is an ion, take the charge on the ion into account. (Example: NO3– has 24 electrons, five from N, six from each O, and one from the negative charge.) 2. Draw a skeletal structure for the molecule with all single bonds. The first atom listed, usually the less electronegative of the atoms, often is the central atom in the structure. H and F atoms are never central atoms. 3. Counting each bond as two electrons, subtract the number of electrons used from the total number available. Place the remaining electrons on the atoms in the structure as non-bonding pairs, so that each atom has a total of 4 pairs of electrons around it. H atoms only require one pair. 4. If there are too many electrons, place the extra electrons in pairs around the central atom. Put them in diagonal positions from the bonds already there. 5. If there are too few electrons, then for each two electrons the molecule is short, place a non-bonding pair into a bonding position to form a multiple bond. 6. If there is more than one position possible for the multiple bond, or if one triple bond could be used in place of two double bonds, then the molecule has resonance structures. Make note of the presence of resonance forms. 7. An atom in a molecule has a formal charge if the number of electrons around the atom in the molecule differs from the number of electrons around the atom as an isolated atom. Show any formal charges other than zero. Consult the textbook for the various VSEPR types. AX2 AX3 AX2E AX4 AX3E AX2E2 AX5 AX4E AX3E2 AX2E3 AX6 AX5E AX4E2 linear trigonal bent tetrahedral trigonal bent trigonal seesaw T shaped linear octahedral square square planar pyramid bipyramid pyramid planar If there is more than one central atom, give the VSEPR designation and shape about each central atom. Consult the textbook for the various Hybrid Orbital types. sp sp2 sp3 sp3d sp3d2 double bonds: one σ and one π bond; the π bond comes from two p orbital electrons on adjacent atoms EXAMPLES Molecule Lewis structure (show any formal charges) VSEPR Type, Shape Hybrid Orbitals H2O AX2E2, bent sp3 on O C2H5OH AX4 on each C, AX2E2 on O, all tetrahedral angles sp3 on C and O SF4 AX4E, seesaw sp3d on S NO3– AX3, trigonal planar sp2 on N, sp2 on right O π bond between N & O There is resonance in the molecule. -N OOO2 Molecule Lewis structure (show any formal charges) VSEPR Type, Shape Hybrid Orbitals CF4 NH3 Cl2O PO43- NH4+ C2H6 C2H4 C2H2 CO3 Name___________________________________________ Grade______ Date___________ Molecule Lewis structure (show any formal charges) VSEPR Type, Shape Hybrid Orbitals XeF4 BrO3– ClO4– I3– NO2 CO32- H2O2 CH3OH