[vhpk]

The electronegativity and electron affinity both express the strong or weak ability of un-metal, but electron affinity has negative and positive value, while electronegativity only has positive value. Why
@enahs: sorry very much

[enahs]

Where are you getting negative values for electronegativity?

Also, some older books will label electron affinity as negative for the noble gases, but now a days that is rejected and they are labeled 0.
http://en.wikipedia.org/wiki/Electron_affinity
http://en.wikipedia.org/wiki/Electronegativity

[vhpk]

The electron affinity of almost metals gets 0 or negative values

[enahs]

The electron affinity of almost metals gets 0 or negative values

No, they do not. That is my point. That is an older standard, they are usually now referred to as positive values.


The change, is however "negative". Say a chlorine atom gains an extra electron to form Cl^-, it releases ~350 kJ/mol.
So it releases 350kJ/mol, or -350 kJ/mol.