Chromium is used to make many things such as paints and dyes, stainless steel, and chrome plating. It also has many other uses but these are three of the most common. It is a very lustrous and shiny metal and gray in color.
You could always do an advertisement such "Our Lives Would Be Dull Without Chromium." Chrome plating is on everything from to license plates covers to wheels and many other items that can be found everywhere, especially on cars and motorcycles.
Chromium also is used to plate metals to prevent corrosion so you could use a slogan such as "Bust the Rust, Use Chromium."
How about "How did this ruby get so red?", accompanied by a photograph of a brilliant ruby? One of the things that jumped out at me while I was reviewing the properties of chromium is that very small amounts of this element give intense colors to other materials. Chromium is often used in the making of pigments. Another sexy use of chromium, of course, is in making the chrome plating on automobile parts.
If I were designed an advertsiing campaign for this element, I wouldn't focus on the scientifc aspects, such as its antiferromagnetic or anticorrosive properties. Big concepts that noone understands won't sell a product, right? Instead, I'd focus on the very real and visually appealing aspects of the element.