Question

Formic acid is the irritating substance that gets on your skin when an ant bites. Its formula is HCOOH. Carbon is the central atom, and it has no \(\mathrm{O}-\mathrm{O}\) bonds. Draw its Lewis structure.

Short answer

Answer: The Lewis structure for formic acid (HCOOH) is: H | O - C - O - H : : : : where "-" indicates a single bond, and ":" represents a lone pair of electrons.

Step-by-step solution

Determine the total number of valence electrons

To begin the process, we will need to find the total number of valence electrons in the formic acid molecule. For this, we need to know the number of valence electrons for each atom: H has 1, C has 4, and O has 6. For HCOOH, we have: - 2 Hydrogen atoms x 1 electron/atom = 2 valence electrons - 1 Carbon atom x 4 electrons/atom = 4 valence electrons - 2 Oxygen atoms x 6 electrons/atom = 12 valence electrons Total = 18 valence electrons

Arrange the atoms in a skeleton structure

Now that we have the total number of valence electrons, it's time to create a skeleton structure. We already know that carbon is the central atom, and there are no O-O bonds. We can start by placing the carbon atom in the center and attaching the oxygen atoms to each side of the carbon (considering there are no O-O bonds). The hydrogen atoms will then be added to the oxygen atoms, creating the layout: H-O-C-O-H.

Add electrons to create bonds

Next, we will add the valence electrons in the skeleton structure, starting with the bonds. A single bond consists of 2 electrons. Since we have 4 atoms to bond (H-O, O-C, C-O, and O-H), we will use 8 of the 18 valence electrons to make these bonds. Place a single bond between each connected atom: H-O, O-C, C-O, and O-H.

Fill the octets for each atom

After the bonds have been formed, we have 10 valence electrons remaining. Now we can complete the octets for each atom, keeping in mind that hydrogen needs only 2 electrons to be satisfied. Start by assigning the remaining electrons to the oxygen atoms: - Fill the octet for the oxygen atoms connected to hydrogen: 1 O atom will require six more electrons to complete its octet (3 lone pairs). Now this oxygen has an octet (2 from the bond and 6 from lone pairs). - Fill the octet for the other oxygen atom: This atom also requires six more electrons to complete its octet (3 lone pairs). Now this oxygen has an octet (2 from each bond and 4 from lone pairs). Finally, assign the remaining electrons to the carbon atom: - The central carbon atom will have 4 more electrons as a lone pair.

Verify the Lewis structure

Verify that the Lewis structure follows the octet rule and that all valence electrons have been used. The hydrogen atoms each have two electrons, the carbon atom has eight electrons, and both oxygen atoms have eight electrons, which satisfies the octet rule. All 18 valence electrons have been used. So, the Lewis structure for formic acid (HCOOH) is: H | O - C - O - H : : : : where "-" indicates a single bond, and ":" represents a lone pair of electrons.