Question

when moving from left to right across a period ionization energy is increasing by which other trend is this caused

Answer 1

Ionization energy increases from left to right across a period primarily due to increasing nuclear charge, which refers to the positive charge of the nucleus from the increasing number of protons. As you move across a period, electrons are added to the same principal energy level while the number of protons in the nucleus increases. This results in a stronger electrostatic force of attraction between the positively charged nucleus and the negatively charged electrons.

In addition to this, another trend that contributes to the increasing ionization energy is the decreasing atomic radius. As you move from left to right, the effective nuclear charge increases, pulling the electrons closer to the nucleus and resulting in a smaller atomic radius. The closer proximity of electrons to the nucleus means that more energy is required to remove an electron, leading to higher ionization energies.

Thus, the increasing ionization energy across a period is mainly caused by:
1. Increasing nuclear charge (more protons).
2. Decreasing atomic radius (electrons are held more tightly).