6 electrons fit in the 3rd energy level.
6 electrons fit in the 3rd energy level.
how many electrons fit in the 3rd energy level?
6
when the voltage applied to a crookes tube is high enough, around 5,000 volts or greater, it can accelerate the electrons to a high enough velocity to create x-rays when they hit the anode or the glass wall of the tube. the fast electrons emit x-rays when their path is bent sharply as they pass near the high electric charge of an atom's nucleus, a process called bremsstrahlung, or they knock an atom's inner electrons into a higher energy level, and these in turn emit x-rays as they return to their former energy level, a process called x-ray fluorescence. many early crookes tubes undoubtedly generated x-rays, because early researchers such as ivan pulyui had noticed that they could make foggy marks on nearby unexposed photographic plates. on november 8, 1895, wilhelm röntgen was operating a crookes tube covered with black cardboard when he noticed that a nearby fluorescent screen glowed faintly. he realized that some unknown invisible rays from the tube were able to pass through the cardboard and make the screen fluoresce. he found that they could pass through books and papers on his desk. röntgen began to investigate the rays full-time, and on december 28, 1895, published the first scientific research paper on x-rays. röntgen
crookes tube
the process of gaining and losing energy is normally random, so under typical conditions, a large group of atoms is unlikely to be in a suitable state for this reaction. lasers depend on some sort of setup that results in many electrons being in the desired states, a condition known as a population inversion. an easy to understand example is the ruby laser, where there is a metastable state where electrons will remain for a slightly longer period if they are first excited to even higher energy. this is accomplished through optical pumping, using the white light of a flash lamp to increase the electron energy to a blue-green or ultraviolet frequency. the electrons then rapidly lose energy until they reach the metastable energy level in the deep red. this results in a brief period where a large number of electrons lie at this medium energy level, resulting in a population inversion. at that point any one of the atoms can emit a photon at that energy, starting the chain reaction.
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