Question

Modern periodic table

Answer 1

A table in which the chemical elements are arranged in order of increasing atomic number. Elements with similar properties are arranged in the same column (called a group), and elements with the same number of electron shells are arranged in the same row (called a period).
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Answer 2

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Modern periodic law states that physical and chemicals properties of elements are periodic functions of their atomic numbers.

Modern periodic table is based on modern periodic law and elements are arranged in increasing order of their atomic numbers.

Features of modern periodic table -:

Modern periodic table has 18 vertical columns called groups.
Elements in any group of the periodic table have similar physical and chemical properties.

There are 7 horizontal rows called periods. 

• First period - It contains just two elements that are Hydrogen and Helium and this period is called the shortest period.

• Second and third period - It contains 8 elements and are called short period.

• Fourth and fifth period - It contains 18 elements and are called long periods.

• Sixth period - There are 32 elements, it has 14 element series called Lanthanide series placed seperately below the main body of periodic table.
Lanthanide series are rare - earth elements that show similar properties.

• Seventh period - It us incomplete period and a series of 14 elements called Actinide series are placed seperately too.



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