The force that must be overcome to remove an electron from an atom is called the ionization energy. This is the minimum amount of energy required to remove an electron from the gaseous atom in its ground electronic state.

Here's a breakdown:

* Electrostatic force: Electrons are attracted to the positively charged nucleus of an atom due to the electrostatic force. This force is what holds the electrons in the atom.

* Ionization energy: To remove an electron, you need to provide enough energy to overcome this electrostatic attraction and pull the electron away. This energy is called the ionization energy.

Factors affecting ionization energy:

* Distance from the nucleus: Electrons closer to the nucleus experience a stronger attraction and thus require more energy to remove.

* Number of protons in the nucleus: A higher number of protons means a stronger attraction, leading to higher ionization energy.

* Shielding effect: Electrons in inner shells can shield outer electrons from the nucleus, making it easier to remove those outer electrons.

* Electron configuration: Electrons in filled or half-filled orbitals are more stable and require more energy to remove.

It's important to note that ionization energy is a specific value for each element and can vary depending on the electron being removed. For example, the first ionization energy refers to the removal of the first electron, while the second ionization energy refers to the removal of the second electron, and so on.