"Chrome" is the generic name for chromium, which after polishing quickly establishes a very thin layer of chromium oxide that resists corrosion better than other metal oxide layers. Chromium is also mixed into steel to create stainless steel.

A chrome finish will have a slightly bluish color, while polished nickel will have a slightly yellow color.

You can indeed change the finish of most metals using one type of oxidizer or another. However, I would not do this myself, as it is quite hazardous, and just about every large town in the US has a chrome shop that can do this far better (and usually cheaper) than a DIYer can. Check the yellow pages for "chrome" or "metal."