As you move left to right across a period in the periodic table, which property generally increases?

As you move left to right across a period in the periodic table, ionization energy generally increases. This phenomenon occurs due to the increasing positive charge of the nucleus as protons are added to the atomic structure while the electrons are added to the same principal energy level. As a result, the effective nuclear charge experienced by the outermost electrons increases. This heightened attraction between the nucleus and these outer electrons means that more energy is required to remove an electron, thus raising the ionization energy.

In addition to this, the addition of protons increases the nuclear charge without significantly increasing the shielding effect because the added electrons are entering the same energy level. Consequently, the electrostatic attraction between the nucleus and the valence electrons becomes stronger, leading to a higher ionization energy. This trend is a critical aspect of understanding periodic trends, as ionization energy influences chemical reactivity and bonding behavior in elements.