Most people, including chemists, prefer to use these common names for the compounds mentioned because they are frequently found, and the common names are shorter, easier to pronounce, and more widely known.
The flashlight's beam will all be refracted towards a central axis. But, this is still dependent on the type of lens that is used for the said activity. The speed of light will vary depending whether the lens is a concave or a convex lens. The exit point of the light will always head towards the central axis.
