Question

(a)Who prepared the modern periodic table?

(b) Define-

• Modern periodic law
• Modern periodic table

Answer 1

(a) In 1869 Russian chemist Dimitri Mendeleev arranged the elements into 8 groups and 7 periods but some issues were there in that periodic table which was later revised by Henry Gwyn Jeffery Moseley. So, the Modern periodic table was led by Mendeleev and revised by H G J Moseley.

(b) Modern periodic law: “The physical and chemical properties of the elements are periodic functions of their atomic numbers”.

Initially, the law was that the physical and chemical properties of the elements are periodic functions of their atomic numbers. which was later revised by Moseley and become a modern periodic law.

Modern periodic table:

• The modern periodic table is used to organize all the known elements. Elements are arranged in the table by increasing atomic number. In the modern periodic table, each element is represented by its chemical symbol. The number above each symbol is its atomic number.
• Modern periodic table contains 18 groups and 7 periods in it has four blocks that is group 1 and 2 belongs to the s-block, group 3 to 12 belongs to the d-block and group 13 to 18 belongs to the p-block elements while the f-block elements are placed below the main periodic table and belong to 3 group only.