Which of the following is the correct Lewis structure for water (H2O)?
А. н-о:Н
B. H:0:
Носно
Н… ноn
The Correct answer and Explanation is:
The correct Lewis structure for water (H₂O) is represented as: H:O(option A).
Explanation of the Lewis Structure for Water (H₂O)
- Understanding Lewis Structures: Lewis structures illustrate the arrangement of atoms and the distribution of electrons in a molecule. They show bonding pairs of electrons (represented by lines or dots) and lone pairs (unshared pairs of electrons) around atoms.
- Count the Valence Electrons:
- Hydrogen (H) has 1 valence electron, and since there are two hydrogen atoms, they contribute a total of 2 valence electrons.
- Oxygen (O) has 6 valence electrons.
- Therefore, the total number of valence electrons in water is 2(from H)+6(from O)=82 (from \, H) + 6 (from \, O) = 8 2(fromH)+6(fromO)=8 valence electrons.
- Drawing the Structure:
- Start with the oxygen atom in the center because it is more electronegative and can form more bonds than hydrogen.
- Each hydrogen atom will bond with the oxygen atom. To represent this, we place a single bond (2 electrons) between the oxygen and each hydrogen. This uses up 4 of the 8 valence electrons.
- Distributing Remaining Electrons:
- After forming two bonds (one with each hydrogen), we have 4 remaining electrons (8 total – 4 used in bonds = 4 left).
- These remaining electrons are placed as two lone pairs on the oxygen atom.
- Final Structure: The final Lewis structure for water is depicted as H:O, showing two hydrogen atoms bonded to the oxygen atom with two lone pairs of electrons on oxygen. This arrangement reflects the molecular geometry of water, which is bent due to the repulsion between the lone pairs, resulting in a bond angle of approximately 104.5 degrees.
- Resonance: Water does not have resonance structures, as the arrangement shown is the most stable and only configuration for this molecule.
Understanding the Lewis structure for water is crucial for comprehending its properties, such as polarity and its role as a solvent in biological systems.