E=1/n^2 (-13.6eV) for other one-electron atoms –ionized helium (Z=2),

[MIA6]

E=1/n^2 (-13.6eV) for other one-electron atoms –ionized helium (Z=2), doubly-ionized lithium (Z=3),etc. I found contradicting here is that one-electron atom and Z=2, 3. If it’s one electron, then there is only one proton, so where do 2 or 3 protons come from?
Thanks.

 

[cepheid]

Umm...doubly ionized Lithium is missing two of it's electrons. Hence it has one electron and three protons. That's why it is IONized.

 

[denian]

I can understand your confusion with the concept of one-electron atoms and their ionization states. Let me clarify this for you.

When we say one-electron atom, we are referring to the number of electrons present in the atom. In this case, it means that there is only one electron orbiting around the nucleus. However, the number of protons in the nucleus can vary. For example, hydrogen has one electron and one proton, while helium has one electron and two protons. This is why helium is considered a one-electron atom.

Now, when we talk about ionization, we are referring to the process of removing one or more electrons from an atom. This can be done by supplying energy to the atom, which causes the electron to jump to a higher energy level or completely leave the atom. In the case of helium (Z=2), it can be ionized to become a doubly-ionized atom (Z=2+2=4) by removing both its electrons.

Similarly, lithium (Z=3) can also be ionized to become a doubly-ionized atom (Z=3+2=5) by removing both its electrons. So, the number of protons in the nucleus does not necessarily match the number of electrons in the atom.

I hope this explanation helps to clear up any confusion. As scientists, we must always question and seek to understand the concepts we come across. Keep up the curious mindset!