Draw and upload a picture of the Lewis structure of H2O (as seen above) with an arrow next to the molecule to show the direction along each of the bonds in which the electron density increases (from low density to high density).
The Correct Answer and Explanation is :
The diagram above represents the Lewis structure of the water (H₂O) molecule. The oxygen atom (O) is depicted in red, with its two lone pairs of electrons shown as dots. The hydrogen atoms (H) are in blue, connected to oxygen by single bonds.
The arrows next to the bonds indicate the direction of increasing electron density. In a water molecule, oxygen is more electronegative than hydrogen, meaning it attracts the shared electrons in the covalent bonds more strongly. Consequently, the electron density increases towards the oxygen atom, as shown by the arrows pointing from hydrogen to oxygen.
Explanation
- Electronegativity and Bond Polarity:
- Electronegativity is a measure of an atom’s ability to attract electrons. Oxygen has a higher electronegativity (3.44) compared to hydrogen (2.20).
- As a result, the shared electrons in the O-H bonds are pulled closer to the oxygen atom, creating a partial negative charge (δ⁻) on oxygen and partial positive charges (δ⁺) on the hydrogen atoms.
- Bond Dipoles:
- The arrows indicate the dipole moment in each O-H bond, pointing towards the more electronegative oxygen atom.
- This shift in electron density leads to a polar covalent bond, with oxygen being the electron-rich center.
- Molecular Polarity:
- The overall structure of water is bent (angular) due to the lone pairs on oxygen, which repel the bonded pairs of electrons.
- This geometry results in an asymmetric distribution of electron density, making water a polar molecule.
The ability of oxygen to attract electrons is crucial to water’s unique properties, such as its high boiling point and ability to form hydrogen bonds.