According to the law of conservation of matter, atoms cannot be created or destroyed during a chemical reaction. what do you think happened to the aluminum atoms after the reaction?

The word atom comes from the Greek atomos which means indivisible, indivisible (excepted in the nuclear reactions). It was therefore perfectly suited to the concept of atom when it was developed by chemists in the early nineteenth century, ie as the smallest part of a pure body.

So the atom of aluminum will remain unchanged, whatever the reaction it will undergo, it is only its molecular form that will change.