Chapter 8, Problem 107A

Interpretation Introduction

Interpretation: The criteria chosen by Mendeleev and Moseley for arranging elements in the periodic table is to be determined.

Concept introduction:

The periodic table is a columnar structure that organizes different elements into groups based on how they behave. The elements in the periodic table of today are ordered according to the periodic law. The elements are organized in the modern periodic table in increasing order of their atomic number.

Answer to Problem 107A

Mendeleev chose atomic mass and Moseley chose atomic number

Explanation of Solution

In Mendeleev's periodic table, the order of the elements was determined by their atomic masses. Only 63 elements were known at the time of Mendeleev's work. Mendeleev discovered a periodic relationship between the qualities of elements and atomic mass. He organized the elements according to increasing atomic mass.

Henry Moseley put forth the modern periodic law in 1913. The physical and chemical characteristics of the elements are periodic functions of their atomic numbers, according to the modern periodic law. Thus, the elements are organized in the modern periodic table in increasing order of their atomic number.