Question

(a) How were the positions of isotopes of an element decided in the modern periodic table?
(b) How were the positions of cobalt and nickel resolved in the modern periodic table?
(c) where should hydrogen be placed in the modern periodic table? Give reason for your answer.

Answer 1

Answer:

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Answer 2

Isotopes Have Same Atomic But Different Mass Number

Explanation:

a.) Modern Periodic Table is based on the Atomic Number of elements and elements are arranged in the increasing order of their atomic number.

Since, isotopes has same atomic number but different atomic masses, and in Modern Periodic Table elements are arranged in the increasing order of their atomic numbers, thus there is no need to assign separate place for them.

b.) Modern Periodic Table is based on the Atomic Number of elements and elements are arranged in the increasing order of their atomic number.

Cobalt has atomic number equal to 27 and nickel has atomic number equal to 28. Thus these elements are placed in their correct order of increasing atomic number.

In Mendeleev's Periodic Table also these elements had same position and order.

c.) Since, elements having same valence electrons are placed in same group and hydrogen have valence electron equal to one, so hydrogen is placed with the elements having same number of valence electrons, in first group. Thus, position of hydrogen in Modern Periodic Table is correct.