Question

explain salient features of modern periodic table

Answer 1

1. The modern periodic table has 7 horizontal rows called 'Period' and 18 vertical columns called 'groups' or families. 2. Periods - 1st period contains 2 elements . It is called very short period. 2nd period contains 8 elements. It is called short period. 3rd period contains 8 elements. It is called a short period. 4th period contains 18 elements. It is called long period. 5th period contains 18 elements. It is also called a long period. 6th period contains 32 elements . It is called very long period. 7th period contains 25 elements. This period is still incomplete. 3. Two series of elements, 14 each, are placed at the bottom of the main periodic table . These are called inner- transition elements. 4 . The 1st series of 14 elements from atomic numbers 58- 71 is called Lanthanide series . The second series of 14 elements from atomic numbers 90-103 is called Actinide series. 5 . Groups - The 18 vertical columns are numbered from 1 to 18. Group 18 is also know as zero group.

Answer 2

Heya!



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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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