They are named as K , L , M , N ... . Where in K is the first shell , L is the second shell , M is the third shell , N is the fourth shell and so on.
At a ground state, argon has three energy levels. For future reference, just count the number of horizontal rows (also named periods) an element is from the top of the periodic table.
Bromine has FOUR energy Levels.
Arsenic has 8 levels of energy.
bismuth has six energy levels
An electron transitioning between levels further apart in an atom's energy levels will release more energy. This is because the energy difference between higher energy levels is greater than that between lower energy levels.
Aluminium Al: 13 2.8.3 So three energy levels
Germanium has 4 energy levels.
Chlorine has three energy levels.
It is all because of a man named Charles Barkla. He was measuring the energy levels of X-rays, and noticed that they came in two main categories, one of which had a higher energy level than the other. He first called them A and B, then realized that there might be levels higher than the one he had called "A". Wanting to leave some room, he decided that K would be a good starting point, and if he later discovered an even higher energy levels he could call them J, I, H and so on down. It turns out there aren't... the K-series was the highest possible energy level for a given atom. But the name had stuck by that point.
Germanium has 4 energy levels.
Iodine has seven energy levels.
Xenon has 6 energy levels.