# why are mercury gas and tungsten filament used in electric bulbs instead of fluorine which has higher electron affinity?

Fluorine has greater electron affinity than mercury or tungsten and hence fluorine could have been in electric bulbs.Because it can attract electrons easily than the metals which mostly repel extra electrons, so fluorine should release more energy[light].Then why wasn't it used?

• Fluorine is way more dangerous than mercury – Lighthart Jul 15 '16 at 15:58
• And etches glass, which isn't good for the bulb. But, it seems to me that the question is driven more on misunderstandings of how the different types of light bulbs work. The connecting of the electron affinity and supposing F would release more light is just wrong. – Jon Custer Jul 15 '16 at 16:03
• and it is not just a $very$ $very$ dangerous gas it reacts with most everything including, I expect, a hot tungsten filament. Mercury is used mainly in high pressure arc lamps, or low pressure discharge lamps and not in domestic filament bulbs. The gas in a domestic light bulb is mainly there to stop the filament oxidising and is usually a rare gas or nitrogen. The bulb may also be evacuated. – porphyrin Jul 15 '16 at 16:28