Problem 47 - Chemistry The Central Science

Question

Write the Lewis structure for each of the following species, and indicate the structure of each: (a) \(\mathrm{SeO}_{3}{\underline{\phantom{xx}}}^{2-} ;\) (b) \(\mathrm{S}_{2} \mathrm{Cl}_{2} ;(\mathrm{c})\) chlorosulfonic acid, \(\mathrm{HSO}_{3} \mathrm{Cl}\) (chlorine is bonded to sulfur).

Step-by-Step Solution

Answer

The Lewis structures for the given species are as follows: (a) \(\mathrm{SeO}_3^{2-}\): O \ Se = O / O (b) \(\mathrm{S}_2\mathrm{Cl}_2\): S - Cl | S - Cl (c) \(\mathrm{HSO}_3\mathrm{Cl}\) (Chlorine is bonded to Sulfur): O \ S - Cl / \ H - O

Step 1: Count valence electrons

To determine the total number of valence electrons, add the valence electrons of each atom and the additional electrons from the negative charge. - Selenium (Se): 6 valence electrons (it's in group 16 of the periodic table) - Oxygen (O): 6 valence electrons each - The 2- charge adds 2 more electrons Total number of valence electrons = 6(Se) + 3*6(O) + 2(charge) = 6 + 18 + 2 = 26

Step 2: Place the central atom and arrange the others around it

Put the least electronegative atom in the center (Se in this case) and arrange the oxygens around it. Se | O

Step 3: Connect the atoms with single bonds

Connect each oxygen to the central selenium atom using a single bond. O \ Se / O

Step 4: Distribute the remaining electrons

Distribute the remaining electrons to complete the octet for each atom. We have used 6 electrons thus far for the single bonds, so there are 20 left to distribute. The Lewis structure becomes: O \ Se = O / O Each oxygen atom has now an octet configuration, and there are no more electrons to distribute. (b) \(\mathrm{S}_2\mathrm{Cl}_2\)

Step 1: Count valence electrons

Determine the total number of valence electrons, adding the valence electrons of each atom. - Sulfur (S): 6 valence electrons each - Chlorine (Cl): 7 valence electrons each Total number of valence electrons = 2*6(S) + 2*7(Cl) = 12 + 14 = 26

Step 2: Arrange and connect the atoms

Since this molecule contains two of each atom, we should connect one S with one Cl to create S-Cl bonds: S - Cl | S - Cl

Step 3: Distribute the remaining electrons

Distribute the remaining electrons to complete the octet for each atom. We have used 4 electrons for the single bonds, so there are 22 left. The final Lewis structure is: S - Cl | S - Cl Each atom has now an octet configuration. (c) \(\mathrm{HSO}_3\mathrm{Cl}\) (Chlorine is bonded to Sulfur)

Step 1: Count valence electrons

Determine the total number of valence electrons, adding the valence electrons of each atom. - Hydrogen (H): 1 valence electron - Sulfur (S): 6 valence electrons - Oxygen (O): 6 valence electrons each - Chlorine (Cl): 7 valence electrons Total number of valence electrons = 1(H) + 6(S) + 3*6(O) + 7(Cl) = 1 + 6 + 18 + 7 = 32

Step 2: Arrange and connect the atoms

Put the least electronegative atom in the center, which is S in this case. Then arrange the other atoms around it and connect them with single bonds: H \ S - O / \ O Cl

Step 3: Distribute the remaining electrons

Distribute the remaining electrons to complete the octet for each atom. We have used 8 electrons for the single bonds, so there are 24 left. The final Lewis structure is: O \ S - Cl / \ H - O Each atom has now an octet configuration.

Key Concepts

Valence Electrons

Valence electrons are the electrons found in the outermost shell of an atom. These particular electrons are crucial because they are involved in forming chemical bonds. The number of valence electrons an atom has determines how it interacts with other atoms.

• Valence electrons can participate in bonding either by being shared between atoms or transferred from one atom to another.
• Atoms seek to achieve stability, often pursuing a fuller outer shell, which is generally 8 electrons for many elements.
• When counting valence electrons, you look at the group number of an element in the periodic table. For example, Selenium (Se) is in group 16 and has 6 valence electrons. Sulfur (S) is also in group 16, so it too has 6 valence electrons, while Chlorine (Cl) in group 17 has 7 valence electrons.

Understanding valence electrons helps us predict bonding behavior as seen when drawing Lewis structures for molecules like \(\mathrm{SeO}_3^{2-}\), \(\mathrm{S}_2\mathrm{Cl}_2\), and \(\mathrm{HSO}_3\mathrm{Cl}\).

Octet Rule

The octet rule is a chemical concept that explains how atoms tend to form bonds to have eight electrons in their outer shell. This provides the atom with a similar electron configuration as that of a noble gas, which is highly stable.

• While the octet rule is a valuable guideline, some elements follow it strictly, while others may have exceptions due to their ability to have expanded octets, such as phosphorus or sulfur.
• For example, in the molecules we have looked at, like \(\mathrm{SeO}_3^{2-}\) and \(\mathrm{S}_2\mathrm{Cl}_2\), each atom is organized to fulfill the octet rule whenever possible.
• In the case of \(\mathrm{SeO}_3^{2-}\), oxygen atoms manage to achieve their octet, and selenium achieves stability through bonding.

In Lewis structures, it's all about satisfying the octet rule, ensuring each atom resembles a noble gas configuration.

Chemical Bonding

Chemical bonding describes the attraction between atoms that allows the formation of chemical compounds. There are various types of chemical bonds, mainly ionic, covalent, and metallic bonds.

• In covalent bonding, atoms share valence electrons to fulfill the octet rule. This can be seen in the molecules we discussed, such as \(\mathrm{S}_2\mathrm{Cl}_2\) and \(\mathrm{HSO}_3\mathrm{Cl}\).
• Ionic bonds, by contrast, occur when electrons are transferred from one atom to another, creating charged ions that attract each other. However, in Lewis structures, we'd generally focus on covalent bonding for molecules like \(\mathrm{SeO}_3^{2-}\).
• The arrangement and type of bonds affect the geometry, polarity, and overall behavior of the molecules.

By understanding chemical bonding, students can visualize the connection between atoms, which is vital for concepts like drawing accurate Lewis structures.