Why does chlorine has most electron affinity in periodic table.
Answers
Electron Affinity Trends :
Atoms and molecules have certain qualities, one of which is electron affinity. As a rule of thumb, when you are looking at the periodic table, you can expect electron affinity to increase as you move from left to right across the periodic table -- excluding the noble gases -- and to decrease when you move down a group. Therefore, elements with the highest electron affinity in the top right corner of the periodic table. Chlorine, however, breaks this rule.
Atomic Orbitals :
Electrons inhabit regions of space in atoms known as orbitals. Each orbital can only hold two electrons and is named to indicate its shape and energy level. The energy levels range from 1 to 7, and the shapes of the orbitals are labelled by "s," "p," "d" and "f." For example, the orbital that the hydrogen electron occupies is the 1s orbital -- "1" refers to the orbital being in the energy level closest to the nucleus, and "s" refers to the symmetrical and spherical shape of the orbital.
Chlorine and Electron Affinity :
As fluorine sits atop chlorine in the periodic table, most people expect it to have the highest electron affinity, but this is not the case. Fluorine is a small atom with a small amount of space available in its 2p orbital. Because of this, any new electron trying to attach to fluorine experiences lower electron affinity from the electrons already living in the element's 2p orbital. Since chlorine's outermost orbital is a 3p orbital, there is more space, and the electrons in this orbital are inclined to share this space with an extra electron. Therefore, chlorine has a higher electron affinity than fluorine, and this orbital structure causes it to have the highest electron affinity of all of the elements.