In a water molecule (H2O), the oxygen atom has two unshared pairs of electrons and two bonding pairs of electrons. How do the unshared pairs affect the bond angle?

They reduce the bond angle to be slightly lower than the tetrahedral bond angle, approximately 104.45 degrees.

Explanation:

The unshared pair of electrons or lone pair electrons in order to have the minimum repulsion possible with each other pushes the other bonding pairs closer together making the bond angle smaller or bent.

The bond angle is slightly lower than the tetrahedral bond angle of 108 degrees, leaving the water molecule with a bent molecular geometry.

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