Explain the terms:
(a) screening effect
(b) penetration effect
(c) metallic character
Answers
a) Screening effect:
The reduction in the attraction force exerted by the center part of atom called “nucleus” on the “valence electrons” due to the electrons presence in the “inner shells” is called the “shielding effect”. This effect increases if there is increase in the electrons numbers between the core and the “outermost electrons” in the “inner shells”.
The screening effect order: “s-orbital” > “p-orbital” > “d-orbital” > “f-orbital”.
b) Penetration effect:
Electrons are “negatively charged” and attracted by the positive charge of the nucleus and also electrons are repelling each other. The balance of force of attraction and repulsion leads to shielding. Therefore, the electron ability gets “close to the nucleus” called penetration.
c) Metallic character:
The “metal character” refers to the “level” of “metal reactivity”. This decreases as we shift from “left to right” through a “period” in the “periodic table”. This happens because atoms accept electrons more readily to fill a “valence shell” than they lose to “remove” the “unfilled shell”.