Final answer:
Ionization energy increases when moving from left to right within a row in the periodic table, due to a stronger nuclear attraction from the additional protons.
Step-by-step explanation:
Periodic Table and Ionization Energy Trend
The ionization energy within the periodic table exhibits a predictable trend. As you move from left to right across a row in the periodic table, the ionization energy for an atom typically increases. This can be attributed to the additional protons in the nucleus, which strengthen the electrostatic interaction between the nucleus and electrons, thereby requiring more energy to remove an electron.
Conversely, as one goes down a group (from top to bottom), the ionization energy decreases because the valence electrons are further from the nucleus and more shielded by filled inner electron shells, making them easier to remove.
Therefore, the answer to the question is: Ionization energy increases from left to right across the periodic table.