The shell structure of an atom starts with an s subshell in shell 1. The s subshell can hold 2 electrons. Helium atoms have 2 electrons. They can either both go in the 1s shell, or one could go into the next shell, no 2 and into its 2s subshell. However, the 2s subshell requires more energy to fill than the remaining slot in the 1s shell, so the electrons will be paired in the 1s subshell. The atom can be excited by external energy, however and that will excite one or both electrons into the next shell. However, that is no a stable state.
The Z scheme, which depicts the energy of an electron as it moves from photosystem II to NADP+
Adenosine triphosphate (ATP) provides energy
Shy children often have a high arousal level in novel social situations. Over time, parents can help ...
Hydrogen burns to produce energy and water
Average real hourly wages (2010 dollars) by education level, full-time workers aged 17 to 34 in 2011
A slice of cheese pizza has a caloric content of 150 Cal. If this energy could b