Peroxide is called H₂O₂ because that is its chemical formula. Here's why:

* H: The "H" stands for hydrogen. Each peroxide molecule contains two hydrogen atoms.

* O: The "O" stands for oxygen. Each peroxide molecule contains two oxygen atoms.

* 2: The subscript "2" after both "H" and "O" indicates the number of atoms of each element present in the molecule.

Therefore, H₂O₂ accurately represents the composition of a peroxide molecule: two hydrogen atoms and two oxygen atoms.