18 total electrons fit in the 3rd energy level including the 1st and second.
18 total electrons fit in the 3rd energy level including the 1st and second.
how many total electrons fit in the 3rd energy level including the 1st and second?
18
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
chemical bonds between atoms in a molecule form because they make the situation more stable for the involved atoms, which generally means the sum energy level for the involved atoms in the molecule is lower than if the atoms were not so bonded. as separate atoms approach each other to covalently bond, their orbitals affect each other's energy levels to form bonding and antibonding molecular orbitals. the energy level of the bonding orbitals is lower, and the energy level of the antibonding orbitals is higher. for the bond in the molecule to be stable, the covalent bonding electrons occupy the lower energy bonding orbital, which may be signified by such symbols as σ or π depending on the situation. corresponding anti-bonding orbitals can be signified by adding an asterisk to get σ* or π* orbitals. a non-bonding orbital in a molecule is an orbital with electrons in outer shells which do not participate in bonding and its energy level is the same as that of the constituent atom. such orbitals can be designated as n orbitals. the electrons in an n orbital are typically lone pairs.
energy level