Science Behind: Rust
Do you know that there’s very little pure iron out there? This is because iron and air bind very easily.
To rust, there needs to be iron, water, and oxygen. When the water hits the pure iron, it reacts by forming a weak acid with the carbon dioxide in the air. The Iron then dissolves and binds with the oxygen in the water (H2O). This leads to the formation of what is known as F2O3, or rust.
Now, if you're looking to avoid this chemical reaction, be cognizant of a few things: keep iron in a dry, room temperature area to avoid the formation of precipitation and moisture.