CHEM 1415 1st EditionLecture 7Unit: Shapes of MoleculesOutline of Current Lecture I. Molecular Shapea. Table 1b. Example Problem 1c. Table 2d. Example Problem 2Current LectureMolecular Shape:- Lewis dot structures account for the number of bonds in a molecule but only give incomplete, two-dimensional picture of the molecular structure- Molecular shape o order in which the atoms are joined to one another and how they are arranged in spaceo shape affects molecular properties- Valence shell electron pair repulsion (VSEPR) theoryo molecules assume a shape that allows them to minimize the repulsions between electron pairs in the valence shell of the central atomTable 1: Basic geometry for distributing two through six electron pairs to minimize repulsionsNumber of Electron Pairs Geometric Name Bond Angles2 Linear 180°3 Trigonal planar 120°4 Tetrahedral 109.5°5 Trigonal bipyramidal 120°, 90°6 Octahedral 90°, 180°These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Example Problem 1:What is the shape of 3−¿∧PC l5PO4¿?Lewis dot structure of 3−¿PO4¿- the central atom has a complete octet of electrons- the four electron pairs have minimal interaction when the point toward the corners of the tetrahedron- ion is a tetrahedralLewis dot structure of PC l5- Central phosphorus atom has an expanded octet with 10 electrons arranged in five bonding pairs- Vertices of a trigonal bipyramid- Cl atoms are not in equivalent positions- There is 120° between Cl atoms in the horizontal triangle and two atoms below the plane of the triangle for an angle of 90°Table 2: The molecular shapes relationship with the number of lone pairs.Number of electron pairs Number of lone pairs shape3 0 Trigonal planar3 1 Bent (120° ¿4 0 Tetrahedral4 1 Trigonal pyramidal4 2 Bent (109.5° ¿5 0 Trigonal bipyramidal5 1 Seesaw5 2 T-shape5 3 Linear6 0 Octahedral6 1 Square pyramidal6 2 Square planar6 3 T-shape6 4 linearExample Problem 2:Determine the shape of S F4∧Br F5using the VSEPR theory.Lewis dot structure of S F4- Five pairs of electrons around sulfur so shape with minimum interaction is a trigonal bipyramid- Need to determine the best location for the lone pair- Lone pair should occupy an equatorial position or seesawLewis dot structure of Br F5- Six electron pairs around the bromine atom so based on octahedron- A lone pair occupies one of the six positions but because it is symmetrical, it can occupy any corner- Square