why does water and hydrogen peroxide have different chemical and physical properties

3 answers

Because they both have different bonds. Water contains stable O-H bonds, whereas hydrogen peroxide contains a much less stable O-O bond as well.

Because there is an extra bond in hydrogen peroxide, the molecule as a different geometry than the water molecule. This already impacts its physical properties, since the molecules will pack in a different way. Also, the lower stability of the O-O bond drives the molecule to try and find a more stable arrangement, increasing its reactivity.
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