Question

Be sure to answer all parts. Determine the shape around each central atom of the following molecule and identify any deviation from ideal bond angles: СН3-0-СН-СН3 (a) Shape around the carbons: trigonal pyramidal bent (V-shaped) tetrahedral trigonal planar Direction of deviation (if any): greater than ideal less than ideal O ideal (b) Shape around the O: O tetrahedral bent (V-shaped) trigonal bipyramidal T-shaped

Answer 1

H 1 THE CH₂-O-CH₂ - CH3 # # All Carbons and the oxygen are spe hybridized. For an ideal tetrahedral carbon center of a molecule [e. g. CHA] , ideal bond angle = 109°28'. Ideal bond angles deviate, when, lone paiors come in place of bond pairs or if the bonds aren't equivalent. From VSEPR theory: Number of hybrid orbitals / hybridisation numbers, of an atom, H = number of Volence electrons of the atom + number of single bonded atoms + anionic charge - Cationic charge.. sp Number of lone pairs, L = H-(number of single bonded atoms 1 + number of double bonded atoms). Hybridisation Shape Linear Trigonal planar Bent (V-shaped) Tetrahedral Trigonal pyramidal Bent (U-shaped) Ilm + 5p2 N - otolo Sp3

Ot (a) shape around the carbons: For carbons, H=} (4+4) = 4 (5p3) = 4 - 4 =0 Henice & shape is Tetrahedral Now, the bond angle deviates from ideal bond angles ; because the atoms bonded to the carbons are not sameie. for a : 3 H-atoms, 1-0-atom. C2 : 2 H-atoms, 1-o-atom, 1-c-atom. C3: 3 H-atoms, i-c-atom. • Direction of deviation: 2 3 - CH₂ CH3 greater than ideal. Since, Oxygen is more electronegative, it pulls the C-o bonded electron pairs toward iteelf thus bond pain bond pain repulsion between c-H and c-o decreases and between c-H and c-H increases. Therefore, bond angle increases from ideal bond angle. This is true for all the carbon atoms. For Cz Oxygen rendes electronegativity to bond C , which in turn pulls, electron paiors from Cz. (6) Shape around the o: H=} (6+2) = 4 (sp3) L= 4-2 = 2 Hence shape is best (v-shaped). HA H ++
For O, the deviation is less than ideal, because of stronger lone pair-lone pair repulsion between the two oxygen lone pairs and lone pair-bond pair repulsion between oxygen lone pairs and O-C bond pairs.