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### Removing the 2nd electron is always harder

Posted: Wed May 02, 2018 4:19 pm
Hi!

Today in lecture we discussed how removing the second electron from an element is always harder. Indeed, the 2nd ionization energy of an element is always higher than the first one. I just didn't really understand the reason behind this statement. Why is it harder to remove an electron from an element when we have already removed an electron before that?

Thank you!!
Anna De Schutter - section 1A

### Re: Removing the 2nd electron is always harder

Posted: Wed May 02, 2018 5:33 pm
the first electron removed is the outermost, meaning it is farthest from the nucleus. The nucleus is positive and electrons are negative, meaning they are attracted to each other. The outermost electron is easiest to take away because the strength of attraction to the nucleus is least because the electron is the farthest away. Once the outermost electron is gone, the next electron will be closer to the nucleus, so the attraction between them will be stronger and thus it will be harder to break the electron away.

### Re: Removing the 2nd electron is always harder

Posted: Wed May 02, 2018 5:49 pm
Yes! and also, maybe i heard him wrong, but he said something about the table with the ionization energies, which would be helpful because then you can use it to calculate the first then the second, etc., energies which then proves that the second is one higher, meaning it is harder to remove.

### Re: Removing the 2nd electron is always harder

Posted: Wed May 02, 2018 9:36 pm
I'm still a bit confused, like if we take away one electron, the second electron could still be on the outermost shell right? Like for oxygen for example, there are 6 electrons in n=2 so wouldn't removing one electron mean that the second electron we remove is still on the outermost shell (n=2)? Why would the ionization energy then be higher for removing the second electron? But I'm probably misunderstanding this. So sorry but thank you for your help!! :)

### Re: Removing the 2nd electron is always harder  [ENDORSED]

Posted: Fri May 04, 2018 1:38 pm
Removing the second electron is always harder because once you remove the first electron, the atom becomes a cation (positive charge) and will exert a greater electrostatic pull on its remaining electrons.

### Re: Removing the 2nd electron is always harder

Posted: Sat May 05, 2018 11:02 am
Thank you Beverly! :)