the outermost s orbital of an atom contains two electrons. always true sometimes true never true

the outermost s orbital of an atom contains two electrons. always true sometimes true never true
Answer
Brief Explanations:
In general, an s - orbital can hold a maximum of 2 electrons. However, for the outermost s - orbital:
- Consider hydrogen ($H$). Its electron configuration is $1s^{1}$, so the outermost s - orbital has 1 electron.
- Consider helium ($He$). Its electron configuration is $1s^{2}$, so the outermost s - orbital has 2 electrons.
- Consider calcium ($Ca$). Its electron configuration is $[Ar]4s^{2}$, so the outermost s - orbital has 2 electrons. But transition metals like copper ($Cu$) have an electron configuration of $[Ar]3d^{10}4s^{1}$ (due to the stability of a full d - subshell), so the outermost s - orbital has 1 electron.
Answer:
Sometimes true