what is the difference between effective nuclear charge and Nuclear charge?explain it in detail.
Answers
In a nucleus of an atom, mainly there are two sub atomic particles, neutrons and protons. Neutrons don't have any electrical charge. But each proton have a positive charge. If there are only proton in a nuclei, the repulsion between those will be higher. (therefore, presence of neutrons is important to bind the protons together in the nuclei.
Effective Nuclear Charge:
Electrons in an atom are arranged in different orbitals. Inside a main orbital, there are other sub orbitals. For each sub orbital two electron in filled. The electron in the last orbital is called Valence electrons, and they are situated farther from the nucleus.
Answer:
(i) Screening effect : The inner shell electrons in an atom screen or shield the outermost valence electrons from the nuclear attraction. This effect is called screening effect or shielding effect. The magnitude of screening effect depends upon the number of inner electrons. Higher the number of inner electrons, greater is the value of screening effect. The screening constant is represented by 'o' (sigma). For example, across a period the electrons enter the same shell. Thus, shielding due to inner electrons remain same. Down a group, a new larger valence shell is added which increases the inner electrons and thus the shielding effect increases
(ii) Effective nuclear charge : Due to screening effect the valency electrons experience less attraction towards nucleus. This reduces the active nuclear charge (z) actually present on the nucleus. This reduced nuclear charge is termed as 'effective nuclear charge. (Z_eff).