The statement that is not correct for the periodic classification of elements is

Options

A. The properties of the elements are the periodic function of their atomic number
B. non metallic elements are lesser in number than metallic elements
C. for transition elements the 3d orbitals are filled with electrons after 3p orbitals and before 4s orbitals
D. none of the above

Answer

To determine which statement is not correct regarding the periodic classification of elements, we need to analyze the properties and characteristics of the periodic table.

### Step-by-Step Solution:

1. **Understanding the Periodic Table**:
The periodic table organizes elements based on their atomic number, electron configuration, and recurring chemical properties. Elements are arranged in rows (periods) and columns (groups).

**Hint**: Remember that the periodic table is organized by atomic number, not mass.

2. **Periodic Properties**:
The properties of elements, such as electronegativity, atomic radius, and ionization energy, show periodic trends. This means that these properties repeat at regular intervals when elements are arranged by atomic number.

**Hint**: Look for trends in properties as you move across a period or down a group.

3. **Classification of Elements**:
Elements are classified into metals, nonmetals, and metalloids. Metals are generally found on the left side and in the center of the periodic table, while nonmetals are found on the right side.

**Hint**: Identify where metals and nonmetals are located on the periodic table.

4. **Evaluating Statements**:
We need to evaluate the statements given about the periodic classification of elements. If a statement suggests that the periodic classification is less than the number of metallic elements or that it does not accurately reflect the properties of elements, it may be incorrect.

**Hint**: Compare each statement against your understanding of the periodic table and its classifications.

5. **Identifying the Incorrect Statement**:
After analyzing the statements, we find that the statement claiming "the periodic classification of elements is less than the number of metallic elements" is incorrect. The periodic classification encompasses all elements, including metals, nonmetals, and metalloids.

**Hint**: Remember that the periodic table includes all elements, so no classification can be "less" than the number of any specific category of elements.

### Conclusion:
The statement that is not correct for the periodic classification of elements is that "the periodic classification of elements is less than the number of metallic elements." The periodic table includes all elements, and the classification does not diminish the number of any type of element.