Two main ingredients are FDA-approved for sunscreen, both of which are very common, but have chemical names that can seem strange.
Titanium dioxide could be called 'Brightener.' It has the unusual quality of being opaque but enhancing brightness. That's why it is found in makeup, for example. For sunscreen, titanium dioxide is made ultra-fine so it is transparent, yet absorbs bad UV light, protecting skin.
Another approved sunscreen is familiar: Zinc Oxide, which could be called 'Reflector.' Naturally occurring in minerals, zinc oxide has been used by humans since about 500 BC. The mineral remains on top of the skin, scattering and reflecting UVA and UVB rays.