Chemical weathering over hundreds of thousands of years formed modern caves. One form of chemical weathering occurs when carbon dioxide reacts with water to produce carbonic acid, H2CO3. How many bonds formed in H2CO3? Each of the elements found in carbonic acid has the number of valence electrons shown:

Question

H valence electrons: 1 C valence electrons: 4 O valence electrons: 6

Based on this information, how many single and how many double bonds are found in carbonic acid?

Answer 1

To determine the number and types of bonds in carbonic acid (H₂CO₃), we start by analyzing its molecular structure based on the valence electrons provided.

1. Valence Electron Counts:

   • Hydrogen (H): 1 valence electron, and there are 2 H atoms → 2 total electrons.
   • Carbon (C): 4 valence electrons, and there is 1 C atom → 4 total electrons.
   • Oxygen (O): 6 valence electrons, and there are 3 O atoms → 18 total electrons.
   • Total valence electrons in H₂CO₃ = 2 (H) + 4 (C) + 18 (O) = 24 valence electrons.

2. Lewis Structure of Carbonic Acid (H₂CO₃):

   • The central atom is Carbon (C), which forms one carbon-oxygen double bond with one O atom and single bonds with the other O atom and both H atoms.
   • The Lewis structure can be represented as:

         O
         ||
      H - C - O - H
     

   • In this structure:
     • 1 Carbon-Oxygen double bond (between C and one O)
     • 2 Carbon-Oxygen single bonds (one C-O bond to the second O, and one H-O bond to both H atoms)

3. Bonds Count:

   • Double Bonds: 1 (C=O)
   • Single Bonds: 3 (C-O and 2 H-O)

In summary, carbonic acid (H₂CO₃) contains 1 double bond and 3 single bonds.