Question

Which of the following Statements are NOT true about the periodic table? 
A. The properties of elements are a function of atomic weights. 
B. The properties of elements are a function of atomic numbers. 
C. Elements having similar outer electronic configuration are arranged in the same period. 
D. An element's location reflects the quantum numbers of the last filled orbital. 
E. The number of elements in a period is the same as the number of atomic orbitals available in the energy level that is being filled.

• A. A, C, and E Only
• B. D and E Only
• C. A and E Only
• D. B, C, and E Only

Hint:

Remember, elements in the same period have the same principal quantum number, and elements in the same group have the same outer electronic configuration. The modern periodic table is based on atomic number, not atomic weight.

Answer 1

The Correct Option is A

To determine which statements about the periodic table are NOT true, let's evaluate each statement one by one: 

1. A. The properties of elements are a function of atomic weights.
   • This statement reflects the initial formulation of the periodic law by Dmitri Mendeleev, where elements were arranged by increasing atomic weights. However, this has since been revised to be based on atomic numbers, as certain anomalies in atomic weight-based ordering were resolved using atomic numbers.
   • Thus, this statement is NOT true according to the modern periodic law, which states that the properties of elements are a periodic function of their atomic numbers.
2. B. The properties of elements are a function of atomic numbers.
   • This statement is true and reflects the modern periodic law established by Henry Moseley, which arranges elements based on increasing atomic numbers, correcting anomalies from Mendeleev's version.
3. C. Elements having similar outer electronic configuration are arranged in the same period.
   • In a periodic table, elements with similar outer electronic configurations are arranged in the same group, not the same period.
   • Therefore, this statement is NOT true.
4. D. An element's location reflects the quantum numbers of the last filled orbital.
   • This statement is true. The position of an element in the periodic table, particularly the group and period, is determined by the quantum numbers, specifically the principal quantum number (n) and azimuthal quantum number (l) of the last filled orbital.
5. E. The number of elements in a period is the same as the number of atomic orbitals available in the energy level that is being filled.
   • The number of elements in a period corresponds to the number of electrons that can occupy the orbitals (subshells) in an energy level, not the number of atomic orbitals.
   • For example, the first period has 2 elements, corresponding to the filling of the 1s orbital, while the second period has 8 elements, corresponding to filling the 2s and 2p orbitals.
   • This statement is NOT true.

Given this analysis, the statements that are NOT true according to the modern understanding of the periodic table are A, C, and E.

Answer 2

Analysis of Periodic Table Statements 

Statement A: The properties of elements are a function of atomic weights. This statement is not true. The modern periodic table is organized based on atomic numbers, not atomic weights. This was a feature of the old periodic table by Mendeleev, where atomic weights were used. Therefore, Statement A is false.

Statement B: The properties of elements are a function of atomic numbers. This statement is true. The modern periodic table is arranged according to the atomic number (the number of protons) of elements. The properties of elements correlate with their atomic numbers, which determine their position in the table and chemical behavior. Therefore, Statement B is true.

Statement C: Elements having similar outer electronic configuration are arranged in the same period. This statement is not true. Elements with similar outer electronic configuration are arranged in the same group (column), not period (row). Elements in the same group have the same number of electrons in their outermost shell, resulting in similar chemical properties. Therefore, Statement C is false.

Statement D: An element's location reflects the quantum numbers of the last filled orbital. This statement is true. The location of an element in the periodic table corresponds to the quantum numbers of the last electron added to its electron configuration. This determines the element's group and period. Therefore, Statement D is true.

Statement E: The number of elements in a period is the same as the number of atomic orbitals available in the energy level that is being filled. This statement is not true. The number of elements in a period is based on the electron capacity of the subshells in that energy level. For example: - The first period has 2 elements (1s orbital), - The second and third periods have 8 elements (2s and 2p or 3s and 3p orbitals), - The fourth period has 18 elements (3d and 4s orbitals), and so on. Therefore, Statement E is false.

Conclusion:

The statements A, C, and E are not true.