Answer to Question #107898 in Chemistry for a

Question

Please predict the bond angles about the central atom in: Words to choose:bent,trigonometry planar,tetrahedral,trigonal bipyramidal,octahedral,0 non bonding pairs,1 non bonding pairs,2 non bonding pairs,109,5 degrees,120 degrees,180 degrees.Thanks

2)BCl3:______electron-domain geometry with ______on B .We confidently predict_____angles. 3)CH3I:______electrin-domain geometry with ____on C.Because the bonding electron domains are not exactly the same,we predict some deviation fro ideal _____ angles

Answer 1

2) Let's consider the electronic structure of the BCl₃ molecule. Its central atom, B, has 3 electrons in its valence shell (you can see this from the Periodic Table, 2s²2p¹). Therefore, when three chlorines share their three electrons with boron, boron atom has three electron pairs in the valence shell ( 3 pairs shared with chlorines). In VSEPR notation, this molecule is described as AX₃, where A is the central atom (boron) and X is the atom linked to the central atom (three chlorines). The electron-domain geometry of AX₃ is trigonal planar. For this geometry, the angle is equal to 120°.

3) Let's consider the electronic structure of the CH₃I molecule. Its central atom, C, has 4 electrons in its valence shell (you can see this from the Periodic Table, 2s²2p²). Therefore, when three hydrogens and one iodine share their four electrons with carbon, carbon atom has four electron pairs in the valence shell ( 3 pairs shared with hydrogens and 1 pair shared with iodine). In VSEPR notation, this molecule is described as AX₄, where A is the central atom (carbon), X is the atom linked to the central atom (three hydrogens and one iodine). The electron-domain geometry of AX₄ is tetrahedral. However, the atoms that make bonds with carbon are not the same, the angle is slightly lower than 109.5°, characteristic for tetrahedral geometry.

Answer: 2)BCl₃: trigonal planar electron-domain geometry with 0 non bonding pairs on B. We confidently predict 120 degrees angles.

3)CH₃I: tetrahedral electron-domain geometry with 0 non bonding pairs on C.Because the bonding electron domains are not exactly the same, we predict some deviation from ideal 109.5 degrees angles.