What type of chemical reaction is
4Fe + 30, ---> 2Fe203

oxidation reaction.

Explanation:

Zerovalent iron is oxidized to give  

Zerovalent oxygen is reduced from  

. Each year significant amounts of money are spent to prevent the corrosion of structural steel. It is inevitably a losing battle.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.