How are electrons held within atoms? What happens to an atom as it becomes an ion? What types of energy changes accompany the addition or loss of electrons from atoms?
Electrons in atoms are attracted to the nucleus with an electrostatic force that exists between the positive charge of the protons and the negative charge of the electrons. In order for an electron to be removed from an atom, an energy source that can overcome the attractive force must be present. The removal of an electron from a neutral atom produces an ion with a positive charge and a free electron.
The first ionization energy of an element is the minimum energy required to remove one electron from a gaseous-state atom of that element. Ionization energies are measured through experimentation. Ionization energy values are also measured for the removal of successive electrons. Thus, a person could consider the energy involved in the removal of the first electron to form a +1 ion or the removal of the second electron to form a +2 ion or the removal of the third electron to form a +3 ion.
