electronegativity

[Fiona Choi 1K]

why does electronegativity increase left-to-right down a period and decrease down the columns?

[rachelcameron2E]

Electronegativity is the combination of electron affinity and ionization energy. As atoms get bigger, going down a group, they decrease in electron affinity and ionization energy (more shielding of outer electrons leads to the atom holding on to them less and less) so electronegativity decreases. Across a period, electron affinity and ionization energy increase (as the atoms will hold tighter to electrons since the new electrons go onto the same shell and thus do not experience increased shielding) so electronegativity increases. I hope this helps!

[Neha Mukund]

Electronegativity increases left to right because the closer an atom gets to having a full octet, the more electronegative it will be. It decreases going down because the more shielding it has from more shells, the less electronegative it becomes. Hope this helps.

[carrie_karchmer_3D]

The way I think about it is that atoms on the right of the periodic table are close to filling an octet so they have the strongest attraction to shared electrons, while atoms on the left are closer to an octet by losing an electron, so they have the weakest attraction to shared electrons. That means that electronegativity would increase from left to right. Also, as you move down a group, atoms increase in size and energy levels, so bonding electrons are further away from the nucleus and hence electronegativity is lesser.

[Irene Kim 3E]

It is also important to keep electron-electron repulsion as a factor in electronegativity. For example, since all elements in the same group (column) have increasing energy levels, the electronegativity will decrease since there are more valence electrons, causing them to repel one another.

[Kayla Ziebell 1H]

Electronegativity increases as it moves right because the electrons are getting closer to 8 valence shell electrons and want to complete their shell by getting more electrons. The electronegativity decreases down the table because as you move down, the element gets another shell added, and thus the electrons are farther spread from the nucleus with the protons, thus the electronegativity is smaller as electrons are not as pulled in.

[Daniel Tabibian 3K]

Electronegativity increases across a period because the atoms are closer to reaching a full octet to reach a more stable form, so they pull on electrons with a greater force. It decreases down a group due to more subshells and electron shielding.

[Nathalia Garibay 1D]

Electronegativity increases left to right because the atom gets closer to having a full octet (the group numbers are an indicator) and thus the elements closest to having full octets will want to fill their valence shells.

[605721741]

Fluorine has only two subshells which means that the electrons are not very shielded. Furthermore it has the most protons in its respective row. This is why it has the highest electronegativity, it holds electrons very well.