Electron Affinity

Moderators: Chem_Mod, Chem_Admin

Mariane Sanchez 1E
Posts: 57
Joined: Fri Sep 29, 2017 7:07 am

Electron Affinity

Postby Mariane Sanchez 1E » Tue Oct 24, 2017 9:39 pm

Hey all,

In which scenario would there be a negative/positive electron affinity? I just can't visualize why there needs to be more energy /release of energy when attaching an electron to an atom.

Priyanka Bhakta 1L
Posts: 50
Joined: Fri Sep 29, 2017 7:04 am

Re: Electron Affinity

Postby Priyanka Bhakta 1L » Wed Oct 25, 2017 9:55 am

Hi!

So electron affinity is the energy released when an electron is added to an atom in the gas phase.

A positive election affinity means that energy is released when an electron attaches to an atom, and this occurs if the atom has many electrons in its valence shell and thus prefers to gain electrons in order to complete its valence shell. So, for atoms of elements in groups 16 and 17, energy is released when an electron is added - and the electron affinity is positive - because the electron is filling the valence shell and

A negative electron affinity means that energy must be supplied to push an electron onto an atom, and this occurs if the atom has less electrons in its valence shell. Since there are only a few I the valence shell, it is easier for the atom to lose those electron than gain them in order to end up with a complete valence shell. Thus, energy must be supplied to the atom in order to force additional electrons to join the valence shell.

It is also important to keep in mind that second electron affinities tend to be lower/more negative because the first addition of an electron to an atom has increased the electron repulsion, and thus, makes it harder to add another electron to the atom.

I hope this clarifies things a bit!


Return to “Trends in The Periodic Table”

Who is online

Users browsing this forum: No registered users and 0 guests