How we can add electron to atom if it is too small?

I have a question about electron affinity?

• Effective nuclear charge of an atom is more when the atom is small in size which means an electron can easily be added to that atom. Then why is electron affinity more i.e., if the nuclear charge is more, then less amnt. of energy is required to add an electron to the atom, then why should more energy be released

• Answer:

  Nuclear charge is nothing but the force of attraction between the nucleus and electrons While adding the electron it is attracted by nucleus but while removing it the work has to be done against the Nuclear force so we need more energy.....