First in school I learnt that when supplied enough energy, the electron in a hydrogen atom will jump energy level(s), denoted by $n=1$, $n=2$ and so on for integral values of $n$. Then I learnt about shells, subshells and orbitals and what they have to do with the quantum numbers $n$, $l$ and $m_l$.
- I'm confused about the difference between energy level and shell, if there is any. The quantum number $n$ tells us the shell, but we also use $n$ to talk about energy levels in hydrogen atom as well.
- When we say that the electron in hydrogen jumps energy levels, does it mean that it is jumping shells? Is it going from the orbital in $1s$ subshell to the orbital in $2s$ subshell? If we supply even more energy, can it go from the orbital in $1s$ subshell to one of the three orbitals in the $2p$ subshell? Do my questions make sense, or am I wrong about some basic fundamentals?
- A comment to a different question said:
"s orbitals have lower energy than p orbitals which have lower energy than d orbitals" This statement is only true when there is more than one electron.
Why is it not true in multi-electron atoms? Is the person referring to the Aufbau Principle i.e. the orbitals in the $4s$ subshell have lower energy than the orbitals in $3d$ subshell?
If I have used any terminology incorrectly, please do let me know.