Question

Why 2nd electron affinity is positive while 1st electron affinity is negative?

Answer 1

Answer:

For the first electron affinity we were adding an electron to a neutral atom, but now we are adding a negative electron to a negative ion so they will repel each other. So to overcome this electrostatic repulsion energy must be added in.

Answer 2

Answer:

2nd electron affinity is always endothermic (positive) because the electron is added to an ion which is already negative therefore it must overcome the repulsion