Effective Nuclear Charge

Consider the following statement I.Electron gain enthalpy becomes more negative with increase in atomic number across a period II.Effective nuclear charge increases from left to right across period III.Electron gain enthalpy becomes less negative as we go up a group Choose the correct option

The size of any species depends on various factors such as nature of charge, magnitude of charge/oxidation state, effective nuclear charge, electronic configuration etc. It has been observed that size of Indium (In) ~~ Thallium (TI). This can be attributed to:

Nuclear charge actually experienced by an electron is termed as effective nuclear charge The effective nuclear Z^(**) actually depends on type of shell and orbital in which electron is actually present. The relative extent to which the various orbitals penetrate is . s gt p gt d gt f (for the same value of n) The phenomenon in which penulitmate shell electrons act as screen or shield in between nucleus adn valence shell electrons and there by reducing nuclear charge is known as sheilding effect. The penultimate shell electrons repel the valence shell electron to keep them loosely held with nucleus . It is thus evident that more is the shielding effect, lesser is the effective nuclear charge and lesser is the ionizatio energy. Ionization energy is not influenced by :

J.C. Slater proposed an empirical constant that represents the cumulative extent to which the other electrons of an atom shield (or screen) any particular electron from the nuclear charge. Thus, slater's screening contant sigma is as : Z^(**)=Z-sigma Here, Z is the atomic number of the atom, and hence is equal to the actual number of protons in the atom. the parameter Z^(**) is the effective nuclear charge, which according to is smaller than Z, since the electron in question is screened (shielded) from Z by an amount sigma . Conversely, an electron that is well shielded from the nuclear charge Z experiences a small effective nuclear charge Z^(**) . The value of sigma for any one electron in a given electron configuration (i.e., in the presence of the other electrons of the atom in question) is calculated using a set of empirical rules developed by slater. according to these rules, the value of sigma for the electron in question is the cumulative total provided by the various other electrons of the atom. Q. Which of the following statement is correct?

J.C. Slater proposed an empirical constant that represents the cumulative extent to which the other electrons of an atom shield (or screen) any particular electron from the nuclear charge. Thus, slater's screening contant sigma is as : Z^(**)=Z-sigma Here, Z is the atomic number of the atom, and hence is equal to the actual number of protons in the atom. the parameter Z^(**) is the effective nuclear charge, which according to is smaller than Z, since the electron in question is screened (shielded) from Z by an amount sigma . Conversely, an electron that is well shielded from the nuclear charge Z experiences a small effective nuclear charge Z^(**) . The value of sigma for any one electron in a given electron configuration (i.e., in the presence of the other electrons of the atom in question) is calculated using a set of empirical rules developed by slater. according to these rules, the value of sigma for the electron in question is the cumulative total provided by the various other electrons of the atom. Q. According to Slater's rule, order of effective nuclear charge (Z^(**)) for last electron in case of Li, Na and K.

J.C. Slater proposed an empirical constant that represents the cumulative extent to which the other electrons of an atom shield (or screen) any particular electron from the nuclear charge. Thus, slater's screening contant sigma is as : Z^(**)=Z-sigma Here, Z is the atomic number of the atom, and hence is equal to the actual number of protons in the atom. the parameter Z^(**) is the effective nuclear charge, which according to is smaller than Z, since the electron in question is screened (shielded) from Z by an amount sigma . Conversely, an electron that is well shielded from the nuclear charge Z experiences a small effective nuclear charge Z^(**) . The value of sigma for any one electron in a given electron configuration (i.e., in the presence of the other electrons of the atom in question) is calculated using a set of empirical rules developed by slater. according to these rules, the value of sigma for the electron in question is the cumulative total provided by the various other electrons of the atom. Q. The effective nuclear charge at the periphery of chromium atom [Z=24]: