Which metal has the most negative electron affinity and why?

Why the electron affinity show that pattern on the periodic table ?

• electron affinity increases across a row and decreases across a column . some answers says that it is because to the attraction of the nucleus between the valence electrons when the atomic size increases this attraction is weaker so it is easier to add an electron but i do not really understands what is teh relationship between the size and adding an electron i think their answer is for the ionization energy not the electron affinity so please give me a right answer with explanation please because i am very confused

• Answer:

  Size, IE and EA are all related by the strength of the nucleus' attraction for its electrons. Across a period, the number of protons in the nucleus increases, so the attraction gets stronger (meaning the size decreases, the IE increases, and the EA increases) Down a group, the electrons are being added to a higher energy level, increasing the distance from the nucleus, and adding an additional layer of electrons that increases the shielding of the nucleus. These two factors decrease the nucleus' attraction for the electrons (meaning the size increases, the IE decreases, and the EA decreases).