Draw the Lewis structure for the chlorofluorocarbon \(\mathrm{CFC}-11, \mathrm{CFCl}_{3}\) . What chemical characteristics of this substance allow it to effectively deplete stratospheric ozone?

The first thing we want to do when drawing a Lewis structure is to identify the central atom. In this case, we have Carbon (C), which will act as the central atom since it has the lowest electronegativity.

Now, we need to determine the number of valence electrons for each atom: - Carbon (C) has 4 valence electrons. - Fluorine (F) has 7 valence electrons. - Chlorine (Cl) has 7 valence electrons. Since we have one Carbon atom, one Fluorine atom, and three Chlorine atoms, we will have a total of 1(4) + 1(7) + 3(7) = 4 + 7 + 21 = 32 valence electrons.

Since the Carbon atom is the central atom, we will connect it to the Fluorine atom and the three Chlorine atoms using single bonds. Each bond uses two electrons, so we used 8 electrons to make these bonds. Now we have 32 - 8 = 24 electrons left. Next, we will distribute the remaining electrons to the outer atoms, starting with the Fluorine atom. We put 6 electrons (3 lone pairs) around the F atom, completing its octet. Now we have 24 - 6 = 18 electrons left. We then place the remaining 18 electrons on the Chlorine atoms, giving each of them 6 electrons (3 lone pairs) as well, completing their octets as well.

The Carbon atom has four single bonds, which completes its octet with 8 electrons. The F and Cl atoms also have full octets, so our structure is complete and stable.

Chemical characteristics of CFC-11 (CFCl3) that allow it to effectively deplete stratospheric ozone are: 1. Stability: The molecule is very stable due to its strong C-F and C-Cl bonds. This stability allows it to remain in the atmosphere for a long period and rise to the stratosphere. 2. UV Absorption: The presence of chlorine atoms in CFC-11 makes it susceptible to photodissociation by UV-C radiation in the stratosphere. This UV radiation causes the molecule to break apart, releasing highly reactive chlorine atoms. 3. Chain Reaction: The chlorine atoms produced by the photodissociation of CFC-11 can catalyze the destruction of ozone (O3) molecules. The highly reactive chlorine atom reacts with an ozone molecule, forming a chlorine monoxide molecule (ClO) and an oxygen molecule (O2). The ClO molecule can react with another O3 molecule, forming another Cl atom and 2 O2 molecules. The newly formed Cl atom can then react with another O3 molecule, continuing the ozone depletion process. This chain reaction can continue for years, destroying thousands of ozone molecules for each Cl atom released by CFC-11. In conclusion, the Lewis structure of CFC-11 (CFCl3) is characterized by a central Carbon atom bonded to one Fluorine atom and three Chlorine atoms. The molecule's stability, UV absorption, and ability to trigger chain reactions account for its effectiveness in depleting stratospheric ozone.