Define : (i) Modern Periodic Law (ii) Modern Periodic Table.
Answers
Modern periodic table is also known as periodic table it is a tabular arrangement in which chemical elements are arranged according to their atomic numbers configuration of electrons and chemical properties
Question 1:
Define Modern Periodic Law.
Answer:
Physical and chemical properties of elements are a periodic function of their atomic numbers (or protons).
Modern periodic law states that the properties of elements are dependent on their atomic numbers and elements show similar properties at regular interval of increasing atomic number.
Also, Modern Periodic law can be stated as:
“The physical and chemical properties of the elements are periodic functions of their atomic numbers”.
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Question 2:
Define Modern Periodic Table.
Answer:
In Modern Periodic Table, the horizontal rows are called periods and the vertical columns are known as the groups.
Groups consist of elements that have similar outer shell electronic configuration in their atoms. Groups are named as 1, 2, 3…18.
In the modern periodic table, periods are the seven horizontal rows. Principle quantum number ‘n’ decides the period of the element. Principle quantum number (n) is one of the four quantum numbers (n, l, m, and s). It tells us about the principle electron shell.
For example, if n= 3, then it indicates the principle shell as 3.
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Classification of the Elements in the Periodic Table:
Classification of the elements in the periodic table can be done in four ways on the basis of their electronic configurations as follow:
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1. Noble gas elements:
Elements of group 18 of the modern periodic table are considered a noble gas. The electronic configuration of the first element (helium) of this group is 1s2. Rest all the elements (neon, argon, krypton, xenon, and radon) have their outer shell electronic configuration is ns2np6. As the octet of these elements is complete, hence they are highly stable elements.
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1. Representative elements:
S-lock and P-block elements come under the category of representative elements. Elements in groups 1 and 2 are known as the s – block elements (elements with 1s2and 2s2 outermost configuration).
Group 13-17 are known as the p-block elements (outermost configuration varies from ns2np1 to ns2np5).
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3. Transition elements:
Elements which belong to group 3 to 12 and have their outer shell electronic configuration as (n-1)d1-10ns1-2 are referred to as transition elements. These elements are also known as the d-block elements.
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4. Inner transition elements:
Lanthanides and actinides series which falls at the bottom of the periodic table comes under the category of inner transition elements. In these elements the 4f and 5f orbitals are partially filled, rendering them special properties.
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