Possible resonance structures for water (H2O)?
The question is –
Can we draw multiple resonance forms for H2O?
Answer:
⇒ No. Multiple resonance structures cannot be drawn for H2O.
Only one Lewis dot structure best represents the water molecule, as shown below.
Explanation:
The best possible Lewis structure of H2O represents an oxygen (O) atom at the center, which is single covalently bonded to two hydrogen (H) atoms, one on either side. There are 2 lone pairs of electrons on the central O-atom.
In this way, the H2O Lewis structure has a total of 8 valence electrons.
The central O-atom has a complete octet while each terminal H-atom has a complete duplet in the H2O Lewis structure.
Also, all the bonded atoms possess zero or no formal charges which indicates the extraordinary stability of this Lewis structure.
Resonance structures are different ways of representing the Lewis structure of a molecule.
Multiple resonance forms of a molecule should all possess the same number of valence electrons.
Atoms possessing lone pairs act as resonance-contributing atoms in a molecule and multiple resonance structures are drawn when a lone pair shifts to form a double bond.
H2O contains O-H single bonds only. The sigma bonds cannot break while drawing resonance structures.
Moreover, as the H-atom can only accommodate 2 valence electrons, thus if we attempt drawing a resonance structure of H2O using a lone pair present on oxygen, the formation of an O=H double bond clearly violates the duplet rule.
It also leads to increased formal charges denoting an overall unstable Lewis structure.
Thus, confirming no resonance structures can be drawn for H2O.
About the author
Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. He holds a degree in B.Tech (Chemical Engineering) and has four years of experience as a chemistry tutor. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. A passion for sharing knowledge and a love for chemistry and science drives the team behind the website. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/