Chapter U1.10, Problem 4E

Interpretation Introduction

Interpretation:

Two elements that have similar properties to that of beryllium, Be, and average atomic masses higher than 130 are to be named.

Concept introduction:

A periodic table was developed by scientists to arrange the elements based on the patterns in their properties. Modern periodic table is a storehouse of information about the elements. There are 18 vertical columns called groups and 7 horizontal rows called periods. Each element square contains information such as element name, symbol, atomic number and average atomic mass.

Answer to Problem 4E

Barium and radium.

Explanation of Solution

In a periodic table, elements are arranged based on the similarities in their properties. The elements are arranged in horizontal periods and vertical groups. Elements of the same group are similar in properties.

Beryllium has an average atomic mass of 9.012 amu. It belongs to group 2A and is an alkaline earth metal. So elements with properties similar to those of beryllium will also belong to group 2A. These elements are magnesium, calcium, strontium, barium and radium. Out of these elements, only barium and radium have atomic masses more than 130. Barium has atomic mass of 137.3 amu and radium has atomic mass of 226 amu. Magnesium, calcium, strontium have atomic masses less than 130. Thus, correct elements are barium and radium.

Conclusion

Thus, the required elements are barium and radium.

They all belong to the second group of alkaline earth metals in the periodic table.