atomisädevaikutuksesta

Atomisädevaikutus, or atomic radius effect, refers to the gradual decrease in atomic size across a period in the periodic table. As you move from left to right across a period, the number of protons in the nucleus increases, leading to a stronger positive charge. Simultaneously, electrons are added to the same principal energy level, or shell. Despite the addition of electrons, the increased nuclear attraction pulls the electron cloud closer to the nucleus, resulting in a smaller atomic radius.

This trend is a fundamental concept in understanding chemical properties. Elements with smaller atomic radii tend to have higher ionization energies and electron affinities because their valence electrons are held more tightly by the nucleus. Conversely, elements with larger atomic radii, typically found on the left side of the periodic table, have valence electrons that are less tightly bound and are more easily removed. The atomic radius effect is a direct consequence of the interplay between nuclear charge and electron shielding. While inner electrons shield the valence electrons from the full nuclear charge, the increasing number of protons across a period outweighs this shielding effect, causing the atomic radius to shrink.