Q.2.52 P - Chemistry: Molecular Nature Of Matter And Change

Question

Correct each of the following statements:

(a) In the modern periodic table, the elements are arranged in order of increasing atomic mass.

(b) Elements in a period have similar chemical properties.

(c) Elements can be classified as either metalloids or nonmetals.

Step-by-Step Solution

Answer

(a) In the modern periodic table, the elements are arranged in order of increasing atomic number. 

(b) Elements in a group have similar chemical properties. 

(c) Elements can be classified as metals, metalloids, or nonmetals.

Step1: How elements are arranged in the modern periodic table

The modern periodic table is also known as the long form of the periodic table in which all the known elements are placed in the table by increasing atomic number. Every element is indicated by its atomic symbol in the modern periodic table. The atomic number of each symbol is shown by the number above it. Hence, the correct statement is “In the modern periodic table, the elements are arranged in order of increasing atomic number”.

Step 2: Use the concept of valence electrons

In the modern periodic table, elements in the same group (vertical column) have the same chemical properties due to the periodic repetition (valence electrons). Therefore, the correct statement is “Elements in a group have similar chemical properties”. 

Step 3: Use the concepts of physical properties to classify each element

All elements fall into three classes such as metals, nonmetals, and metalloids (semimetals). Each class's elements all share some fundamental properties such as physical states, ductility, thermal conductivity and electrical conductivity. Hence, the correct statement is “Elements can be classified as metals, metalloids, or nonmetals”.