Molecular Geometry Exercise \(\PageIndex{1}\) What is the molecular geometry around an atom in a molecule or ion which is surrounded by zero lone pairs of electrons and four single bonds. Answer tetrahedral Exercise \(\PageIndex{2}\) What is the electron-pair geometry around an atom in a molecule or ion which is surrounded by two lone pairs of electrons and three single bonds. Answer trigonal bipyramidal Exercise \(\PageIndex{3}\) The molecular geometry of a molecule whose central atom has four single bonds and one lone pair of electrons is ________. Answer trigonal-bipyramidal Exercise \(\PageIndex{4}\) What is the bond angle in a trigonal planar molecule or ion? Answer 120° VSEPR Exercise \(\PageIndex{5}\) What is the molecular geometry around the nitrogen atom as per the valence shell electron-pair repulsion (VSEPR) theory?? Answer trigonal pyramidal Exercise \(\PageIndex{6}\) What is the molecular geometry around carbon atom C 1 ? Answer trigonal planar Exercise \(\PageIndex{7}\) Use VSEPR theory to predict the electron-pair geometry and the molecular geometry of nitrogen trichloride, NCl 3 . The electron-pair geometry is linear, the molecular geometry is linear. The electron-pair geometry is trigonal-planar, the molecular geometry is trigonal-planar. The electron-pair geometry is trigonal-planar, the molecular geometry is bent. The electron-pair geometry is tetrahedral, the molecular geometry is tetrahedral. The electron-pair geometry is tetrahedral, the molecular geometry is trigonal-pyramidal. Answer e. The electron-pair geometry is tetrahedral, the molecular geometry is trigonal-pyramidal. Exercise \(\PageIndex{8}\) Use VSEPR theory to predict the electron-pair geometry and the molecular geometry of boron tribromide, BBr 3 . The electron-pair geometry is trigonal-pyramidal, the molecular geometry is trigonal-pyramidal. The electron-pair geometry is trigonal-planar, the molecular geometry is trigonal-planar. The electron-pair geometry is trigonal-planar, the molecular geometry is bent. The electron-pair geometry is tetrahedral, the molecular geometry is trigonal-pyramidal. The electron-pair geometry is trigonal-pyramidal, the molecular geometry is t-shaped. Answer b. The electron-pair geometry is trigonal-planar, the molecular geometry is trigonal-planar. Bond Angles Exercise \(\PageIndex{9}\) Based on electron-pair geometries, which of the following molecules has the smallest bond angle between any two adjacent atoms? a. CH 4 b. H 2 O c. BH 3 d. PH 3 e. SF 6 Answer e. SF 6 Exercise \(\PageIndex{10}\) What are the approximate H−N−H bond angles in NH 4 + ? Answer 109.5° Exercise \(\PageIndex{11}\) What is the O−C−N bond angle in OCN – ? Answer 180° Exercise \(\PageIndex{12}\) What are the approximate F−Br−F bond angles in BrF 5 ? Answer 90° and 180° Exercise \(\PageIndex{13}\) In PCl 5 , the Cl−P−Cl bond angle between an axial and an equatorial chlorine atom is ________ degrees. Answer 90 Exercise \(\PageIndex{14}\) Place the following molecules in order from smallest to largest H−N−H bond angles: NH 4 + , NH 3 , and NH 2 – . NH 4 + < NH 3 < NH 2 – NH 4 + < NH 2 – < NH 3 NH 2 – < NH 3 < NH 4 + NH 2 – < NH 4 + < NH3 NH 3 < NH 2 – < NH 4 + Answer c. NH 2 – < NH 3 < NH 4 +