you have to show us the rest of it because we have no idea what your looking at. I'm sorry
Decomposition.
Decomposition is the chemical reaction in which a compound breaks down into the two elements or molecules that formed the compound. In this case, Dialuminium Trioxide has broken down into the basic components of Al2 and O2.
Hope this helps!
It's a FUSION reaction because Iron and Oxygen react together to make Iron Oxide (rust) and it's EXOTHERMIC because the reaction forms heat (stated above), which means it's releasing energy.
If we knew the number of electrons in the outermost shell, the valence electrons, then we could find the valency of the element by calculating how many electrons need to be gained or lost to achieve stable electronic configuration.
For example, if an element has 7 valence electrons, and requires 8 valence electrons to be stable, then its valency will be -1.
