system
Given the following post, respond as if you're commenting on Reddit:
human
What about it's electron configuration makes titanium such a chemically resistant metal and so different from other transition metals?
gpt
Ironically, Titanium is resistant to corrosion because it is incredibly reactive in its pure form. 

This allows it to react strongly with oxygen, forming the incredibly stable TiO2. TiO2 forms a film over the pure titanium, keeping it well insulated and protected.

But most transition metals form strong bonds with oxygen (even kids know what rust is!) So why is this oxide helpful?

Transition metals are unusual elements because they have unfilled orbitals so close together that electrons can settle in different oxidation states. (Orbitals are stable when empty, half-full, or full). So an iron ion could have a +2 or +3 charge. When oxygen bonds to iron, you get both FeO and Fe2O3. These are two different compounds, trying two form two different crystal structures. The two structures interfere with eachother and don’t mesh together, resulting in a destructive, flakey rust.

However, Titanium has so few electrons across these two orbitals (4) that it can’t shuffle them into new stable positions. Further, it has so few electrons that its relatively cheap in energy to remove all of them. This means that Titanium only has a single oxidation state of +4 and ALL bonding with oxygen results in TiO2. Unlike with iron, there is a single compound with no competitors. As a result, TiO2 can form a smooth film over the rest of the titanium, protecting it.