Yes, valence electrons are generally the most difficult to remove from an atom. Valence electrons are the electrons located in the outermost energy level or valence shell of an atom. These electrons are held less tightly by the nucleus compared to the electrons in inner shells.
The attraction between the positively charged nucleus and the negatively charged electrons decreases as you move farther away from the nucleus. As a result, valence electrons experience weaker electrostatic forces and are more likely to be involved in chemical reactions or bonding.
When an atom undergoes ionization, it loses or gains electrons to achieve a more stable electron configuration. Removing an electron from an atom requires overcoming the electrostatic attraction between the negatively charged electron and the positively charged nucleus. Since valence electrons are farther from the nucleus and experience weaker attraction, they are generally easier to remove compared to inner electrons.
However, it's important to note that the ease of removing an electron also depends on factors such as the effective nuclear charge (the net positive charge experienced by an electron) and the shielding effect (the repulsion between electrons in different energy levels). These factors can influence the ionization energy required to remove an electron from an atom.