At room temperature, chlorine is a yellowish gas, bromine is a brown liquid, and iodine is a shiny blue-black solid. Why are these elements considered similar enough to group together on the periodic table?

Which of the following statements is true about energy quantization at the atomic level? electrons in the outermost orbits are the most stable. electrons in all the orbits around the nucleus have the same amount of energy. electrons in the orbit closest to the nucleus have the least amount of energy. electrons absorb or release the same amount of energy independent of the energy levels.