Question

There are 18 elements in the fourth period of the modern periodic table. Explain.​

Answer 1

Explanation:

Classification of Elements and Periodicity in Properties. Account for the fact that the 4th period has eighteen and not eight elements. Therefore, 18 elements (not eight) are present in the 4th period. The 4d and 4f sublevels are higher in enthalpy than 5s and hence are filled up in the next periods.

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Answer 2

Answer:

Classification of Elements and Periodicity in Properties. Account for the fact that the 4th period has eighteen and not eight elements. Therefore, 18 elements (not eight) are present in the 4th period. The 4d and 4f sublevels are higher in enthalpy than 5s and hence are filled up in the next periods.

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