Question

Important merits of the modern periodic table -

• A. it explains why elements in the same group have the same chemical properties
• B. hydrogen has been placed accurately
• C. isotopes have been placed in the same position
• D. it is based on classifying elements according to their atomic number

Answer 1

Answer: (A), (C), (D)

it is based on classifying elements according to their atomic number

Explanation of correct option:

(A)

• The modern periodic table consists of 18 vertical columns.
• The vertical columns are known as groups.
• The placement of elements in the modern periodic table is based on their electronic configuration.
• The number of valence electrons determines the group of an element and vice versa.
• Thus, the elements which have the same number of valence electrons are placed in the same group.
• All the elements of a group have the same chemical properties because they have an equal number of electrons.

(C)

• The modern periodic table is the arrangement of elements in increasing order of their atomic numbers.
• Isotopes are placed in the same position because elements are arranged in increasing order of their atomic number.

(D)

• The modern periodic table was discovered by Henry Moseley.
• Henry Moseley found that atomic number is a better fundamental property of elements compared to atomic mass.
• In the modern periodic table, the elements are arranged in the order of their increasing atomic number.

Explanation of incorrect option:

(B)

• Hydrogen resembles the properties of both the alkali metals and halogens but it has been placed with the alkali metals.
• Thus, the position of hydrogen is not accurate in the modern periodic table.

Conclusion:

Hence, option (A), (C), and (D) is correct and Important merits of the modern periodic table are it explains why elements in the same group have the same chemical properties, isotopes have been placed in the same position and it is based on classifying elements according to their atomic number