Iron + aluminum oxide

Thermite Reaction

Explanation:

The reaction between iron(III) oxide and aluminum produces aluminum oxide and iron. The chemical equation of the reaction is: This reaction is known as a thermite reaction and is highly exothermic. The large amount of heat released is enough to melt oxygen and aluminum.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.