Many tables were made to arrange the elements in an ordered manner based on their characteristics to study the properties of elements in a fixed pattern.
The periodic table is the arrangement of the elements in tabular form according to their properties so that similar elements fall within the same vertical column and dissimilar elements are separated.
The modern Periodic law can be stated as: The physical and chemical properties of the elements are periodic functions of their atomic numbers.
The arrangement of elements in the long form of periodic table is a perfect matching of electronic configuration of the elements on one hand and physical and chemical properties of the elements on the other.
Table: This summarises the names of the elements with an atomic number above 100.
It is the nuclear attractive force experienced by the e- when it is shielded by inner lying electrons. In simpler words , effective nuclear charge measures the force exerted on an electron by the nucleus. A higher effective nuclear charge results in a greater attractive force, pulling electrons closer to the nucleus.
The e-s of the inner shell repels the e-s of outermost shells. This effect is known as the screening or shielding effect.
The penetrating power of e-s towards the nucleus in a given shell decreases in the order s > p > d > f.
Example: ‘K’ = (1s2)(2s2p6)(3s2p6)(4s1).
The ENC experienced by ‘4s’ e- is Z* = Z - S = 19 - (0.85 × 8) + (1.00 × 10) = 2.20
If we consider the E.C. of K as (1s2)(2s2p6)(3s2p6)(3d1) then Z* would be
Z* = 19 - (1 × 18) = 1
Thus the e- in the 4s orbital is under the influence of the greater effective nuclear charge and hence in the ground state, it is this orbital that is occupied.
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1. What is the significance of the periodic classification of elements in chemistry? |
2. How are elements classified as metals, non-metals, and metalloids in the periodic table? |
3. What is the IUPAC nomenclature for elements with atomic numbers greater than 100? |
4. What is effective nuclear charge (Z*) and how is it calculated? |
5. What are Slater's rules and how do they help in estimating effective nuclear charge? |
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