Sigma rule ??~girl's attitude status #shorts whatsapp status #motivation #sigma #quotes

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.

Pauling give method to calculate univalent ion radii by assuming that (i) In ionic crystal (let M^(+)X^(-)) cations and anions are is contact of eac other and sum of their radii is equal to interionic distance, i.e., d_((M^(+)-X^(-)) = r_(M^(+) +r_(X^(-)) (ii) The radius of an ion having noble gas configuration is inversely proportional to the effective nuclear charge felt at the periphery of the ion, i.e., r_((M^(+))) = (C)/(Z_(eff(M^(+)))) and r_((X^(-))) = (C)/(Z_(eff(X^(-)))) Here C is constant of proportionality whose value depends on electronic configuration of ion. Thus, d_((M^(+)-X^(-))) =(C)/(Z_(eff(M^(+)))) +(C)/(Z_(eff(X^(-)))) pm Z_(eff) is the effective nuclear charge whose value can be calculated by the formula: Z_(eff) = Z - sigma . Here sigma is shielding constant and for neon, the value of sigma when calculate by Slater's rule is found to be 4.5 The value of univalent radii for F^(-) as calculated by Pauling method is (given that interionic distance of NaF = 231 pm):

Pauling give method to calculate univalent ion radii by assuming that (i) In ionic crystal (let M^(+)X^(-)) cations and anions are is contact of eac other and sum of their radii is equal to interionic distance, i.e., d_((M^(+)-X^(-))) = r_(M^(+) +r_(X^(-)) (ii) The radius of an ion having noble gas configuration is inversely proportional to the effective nuclear charge felt at the periphery of the ion, i.e., r_((M^(+))) = (C)/(Z_(eff(M^(+)))) and r_((X^(-))) = (C)/(Z_(eff(X^(-)))) Here C is constant of proportionality whose value depends on electronic configuration of ion. Thus, d_((M^(+)-X^(-))) =(C)/(Z_(eff(M^(+)))) +(C)/(Z_(eff(X^(-)))) pm Z_(eff) is the effective nuclear charge whose value can be calculated by the formula: Z_(eff) = Z - sigma . Here sigma is shielding constant and for neon, the value of sigma when calculate by Slater's rule is found to be 4.5 The value of 'C' for Na^(+), Mg^(2+) and Al^(3+) will be in the order:

In this section you have few short passages. After each passage, you will find some items based on the passage. First, read a passage and answer the items based on it. You are required to select your answers based on the contents of the passage and opinion of the author only. Passage During the past three generations the diseases affecting western societies have undergone dramatic changes. Polio, diphtheria, tuberculosis, commonly known as TB, are vanishing, one injection of an antibiotic often cures deadly diseases such as pneumonia or syphilis, and so many mass killers have ·come under control that two-thirds of all death are now associated with the diseases of old age. Those who die young are more often than not victims of accidents, violence, or suicide. These changes in health status are generally equated with the decrease in suffering and attributed to more or better medical care. Almost everyone believes that at least one. of his friends would not be alive and well except for the skill of a doctor. But there is in fact no evidence of any direct relationship between this change in the pattern or nature of sicknesses on the one hand and the so called progress of medicine on the other hand. These changes are the results of political technological changes. They are not related to the activities that require the preparation and status of doctors or the costly equipment in which doctors take pride. In addition, an increase in the number of new diseases in the last fifteen years are themselves the result for medical intervention. They are doctor made or iatrogenic. More death are now associated with old age than in the past because

In this section you have few short passages. After each passage, you will find some items based on the passage. First, read a passage and answer the items based on it. You are required to select your answers based on the contents of the passage and opinion of the author only. Passage During the past three generations the diseases affecting western societies have undergone dramatic changes. Polio, diphtheria, tuberculosis, commonly known as TB, are vanishing, one injection of an antibiotic often cures deadly diseases such as pneumonia or syphilis, and so many mass killers have ·come under control that two-thirds of all death are now associated with the diseases of old age. Those who die young are more often than not victims of accidents, violence, or suicide. These changes in health status are generally equated with the decrease in suffering and attributed to more or better medical care. Almost everyone believes that at least one. of his friends would not be alive and well except for the skill of a doctor. But there is in fact no evidence of any direct relationship between this change in the pattern or nature of sicknesses on the one hand and the so called progress of medicine on the other hand. These changes are the results of political technological changes. They are not related to the activities that require the preparation and status of doctors or the costly equipment in which doctors take pride. In addition, an increase in the number of new diseases in the last fifteen years are themselves the result for medical intervention. They are doctor made or iatrogenic. The writer probably is arguing for