Question

Oxalic acid, \(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4},\) is a poisonous compound found in rhubarb leaves. Draw the Lewis structure for oxalic acid. There is a single bond between the two carbon atoms, each hydrogen atom is bonded to an oxygen atom, and each carbon is bonded to two oxygen atoms.

Short answer

Question: Draw the Lewis structure for oxalic acid, H2C2O4, and describe the process of creating it. Answer: The Lewis structure for oxalic acid, H2C2O4, can be drawn by following these steps: 1. Determine the total number of valence electrons: 2(1) + 2(4) + 4(6) = 36 electrons 2. Arrange the atoms in the molecule: HOC-COCOH 3. Distribute the valence electrons, initially placing 8 electrons in single bonds and assigning 2 lone pairs (4 electrons) to each of the four oxygen atoms. 4. Check for any additional bonding and form double bonds between carbons and two oxygen atoms to achieve a full octet for all atoms. 5. Draw the final Lewis structure: O || H-O-C-C-O-H || O

Step-by-step solution

Determine the total number of valence electrons

Oxalic acid has the chemical formula \(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\). The number of valence electrons for each element are as follows: H has 1, C has 4, and O has 6. The total number of valence electrons in the molecule will be: \((2\times1)+(2\times4)+(4\times6)=36\) electrons.

Arrange the atoms

We know that two carbon atoms are bonded together with a single bond, hydrogen atoms are bonded to oxygen atoms, and each carbon atom is bonded to two oxygen atoms. Therefore, the preliminary arrangement can be represented as \(\mathrm{HOC-COCOH}\). Each '-' represents a single bond: 4 bonds in total.

Distribute the valence electrons

Each single bond (line) has 2 electrons, so we have used 8 of our 36 valence electrons. Now, distribute the remaining 28 electrons around the oxygen atoms as lone pairs. Since each oxygen needs to have a full octet, we will assign two lone pairs (4 electrons) to each of the four oxygen atoms.

Check for any additional bonding

After adding 2 lone pairs to each oxygen atom, we can see that both carbon atoms do not have a full octet. Two of the oxygen atoms have only one bond, so they can form a double bond with each carbon atom. With a double bond between carbons and oxygens, every atom now achieves a full octet.

Draw the Lewis structure

Based on the steps mentioned above, the Lewis structure for oxalic acid, \(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4},\) can be represented as follows: O || H-O-C-C-O-H || O

Key concepts

Valence Electrons Calculation

When constructing the Lewis structure for a molecule, the first step is to calculate the total number of valence electrons available. Valence electrons are the electrons located in the outermost shell of an atom, playing a crucial role in chemical bonding.

For oxalic acid, with the molecular formula \( \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4} \), we calculate valence electrons by summing up the contributions from each atom: hydrogen (\

Molecular Structure Representation

Visualizing the molecular structure of a compound starts with a correct arrangement of its atoms. The Lewis structure is a two-dimensional representation that shows the arrangement and bonding between atoms, as well as the lone pairs of electrons.

For oxalic acid, we know that each of the two carbon atoms forms a single bond with the other. Hydrogen atoms are bonded singularly to oxygen atoms, and each carbon is also bonded to two oxygen atoms. Such preliminary arrangements guide us through the distribution of the valence electrons.

Chemical Bonding and Lone Pairs

Chemical bonds are formed when atoms share valence electrons, while lone pairs are unshared electrons that still belong to a single atom. In the Lewis structure, a line represents a bond (each line accounts for two electrons), and lone pairs are depicted as dots adjacent to the atoms.

In oxalic acid, each hydrogen forms a bond with an oxygen atom. Each carbon atom is bonded to two oxygen atoms. After creating the bonds, we then place lone pairs on the oxygen atoms, ensuring that each has a complete set of electrons in its outer shell.

Octet Rule in Molecules

The octet rule states that atoms tend to form chemical bonds in such a way that they each have eight electrons in their valence shell, giving them the same electronic configuration as a noble gas. Every atom seeks to achieve this stable configuration.

In the final step of drawing the Lewis structure for oxalic acid, we ensure that each oxygen atom has eight electrons by forming double bonds where necessary. After fulfilling the octet rule for all atoms, the structure is complete, accurately reflecting the stability of the molecule.