Final answer:
The ionization energy generally increases from left to right across a period on the periodic table. This is because the number of protons in the nucleus increases, resulting in a stronger attraction between the nucleus and the valence electrons.
Step-by-step explanation:
The ionization energy trend across a period on the periodic table is that it generally increases from left to right. This means that the ionization energy of elements tends to get higher as you move from left to right within a period.
This trend occurs because as you move across a period, the number of protons in the nucleus increases, resulting in a stronger attraction between the nucleus and the valence electrons. This stronger attraction requires more energy to remove an electron, hence the increase in ionization energy.
For example, comparing the ionization energies of lithium (Li) and neon (Ne), lithium has a lower ionization energy because its valence electron is further from the nucleus and experiences less attraction. In contrast, neon has a higher ionization energy because its valence electrons are closer to the nucleus and experience a stronger attraction.