Ionization energy usually increases across which type of periodic trend?

Ionization energy refers to the amount of energy required to remove an electron from an atom in its gaseous state. As you move from left to right across a period in the periodic table, ionization energy generally increases. This trend occurs due to several factors.

Firstly, as you move across a period, the number of protons in the nucleus increases, which enhances the positive charge of the nucleus. This increased nuclear charge creates a stronger attraction between the nucleus and the electrons surrounding it. Therefore, more energy is needed to overcome this attractive force and remove an electron.

Additionally, electrons are being added to the same energy level (the same principal quantum shell) as you move across a period. As these electrons are added to the same shell, the increase in positive charge from the additional protons does not allow for significant shielding. Consequently, the effective nuclear charge experienced by the outermost electrons increases, leading to a greater ionization energy.

In contrast, as you move down a group in the periodic table, the ionization energy generally decreases, as the atomic radius increases. With more energy levels being added, the outer electrons are further away from the nucleus and feel more shielding from the inner electrons, making them easier to remove. Other options do not reflect