Draw lewis structures for the following molecules HCOOH and CO₂^-2

To draw Lewis structures for the molecules HCOOH (formic acid) and CO₂^2- (carbonate ion), we need to follow a systematic approach. This involves determining the total number of valence electrons, arranging the atoms, and ensuring that each atom satisfies the octet rule where applicable. Let’s break down each molecule step by step.

Lewis Structure of HCOOH

Formic acid, HCOOH, consists of one carbon (C) atom, two oxygen (O) atoms, and two hydrogen (H) atoms. Here’s how to draw its Lewis structure:

Step 1: Count Valence Electrons

• Hydrogen (H): 1 x 2 = 2 electrons
• Carbon (C): 4 electrons
• Oxygen (O): 6 x 2 = 12 electrons

Total = 2 + 4 + 12 = 18 valence electrons

Step 2: Arrange Atoms

Carbon is the central atom because it can form four bonds. The arrangement is H-C(=O)-O-H, where one oxygen is double-bonded to carbon and the other is single-bonded.

Step 3: Distribute Electrons

Place the double bond between carbon and one oxygen. The other oxygen will have a single bond with carbon and will carry a negative charge, while the hydrogen atoms will be bonded to the carbon and the negatively charged oxygen.

Final Structure

The Lewis structure can be represented as follows:

H₂C(=O)O^-

In this structure, carbon has four bonds (two with hydrogen, one with oxygen via a double bond, and one with oxygen via a single bond), and all atoms satisfy the octet rule.

Lewis Structure of CO₂^2-

The carbonate ion, CO₃^2-, consists of one carbon atom and three oxygen atoms. Here’s how to construct its Lewis structure:

Step 1: Count Valence Electrons

• Carbon (C): 4 electrons
• Oxygen (O): 6 x 3 = 18 electrons
• Charge: 2 additional electrons due to the 2- charge

Total = 4 + 18 + 2 = 24 valence electrons

Step 2: Arrange Atoms

Carbon will be the central atom, surrounded by three oxygen atoms. The initial arrangement is C surrounded by O atoms.

Step 3: Distribute Electrons

To satisfy the octet rule, we can form one double bond between carbon and one oxygen atom, while the other two oxygens will have single bonds with carbon. Each of the singly bonded oxygens will carry a negative charge, balancing the overall 2- charge of the ion.

Final Structure

The Lewis structure can be depicted as:

O^- - C(=O) - O^-

In this structure, carbon is surrounded by three oxygen atoms, with one double bond and two single bonds, ensuring that all atoms achieve a full octet.

Both Lewis structures illustrate how atoms bond and share electrons to achieve stability, reflecting the underlying principles of molecular structure and bonding. If you have any further questions about these structures or related concepts, feel free to ask!