First ionization energy is the energy needed to remove one electron from a neutral gaseous atom. What is the usual trend across a period from left to right?
Q1. First ionization energy is the energy needed to remove one electron from a neutral gaseous atom. What is the usual trend across a period from left to right?
Answer: It generally increases because effective nuclear attraction to valence electrons rises
Explanation: Across a period, the nuclear charge increases while electrons are added to the same shell, increasing effective nuclear charge and pulling valence electrons closer, so more energy is needed to remove them.