Question

The compound TCDD, or 2,3,7,8−tetrachlorodibenzo−p−dioxin, is highly toxic: h5bur9107 It gained considerable notoriety in 2004 when it was implicated in the attempted murder of a Ukrainian politician. (a) Select the statements that describe its geometry, and whether or not the molecule has a dipole moment. The oxygen atoms are sp2 hybridized and the molecule is planar. The oxygen atoms are sp3 hybridized and the molecule is planar. The oxygen atoms are sp3 hybridized and the molecule is not planar. The molecule is polar. The molecule is not polar. (b) How many pi bonds and sigma bonds are there in the molecule? 6 pi bonds sigma bonds

Answer 1

TCDD's oxygen atoms are sp² hybridized and the molecule is planar, which classifies TCDD as a nonpolar molecule. TCDD contains 10 sigma bonds and 4 pi bonds.

Step-by-step explanation:

To address the question of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) structure and polarity: TCDD's oxygen atoms are sp2 hybridized which contributes to the molecule’s planar shape. Each oxygen forms a π-bond using the p-orbital perpendicular to the plane of the molecule.

Therefore, the correct statement about its geometry is that the oxygen atoms are sp2 hybridized and the molecule is planar. Regarding its polarity, due to the molecule’s symmetrical shape and even distribution of the electronegative chlorines, TCDD does not have a net dipole moment, indicating that the molecule is not polar.

For the bond count in TCDD: there are a total of 10 sigma (σ) bonds and 4 pi (π) bonds. This includes single covalent (sigma) bonds and double bonds consisting of one sigma and one pi bond each.