Moden periodic law states that the properties of the elements are periodic functions of their

Options

A. Atomic number
B. Electronic configuration
C. Atomic mass
D. Atomic size

Answer

**Step-by-Step Solution:**

1. **Understanding Modern Periodic Law**: The modern periodic law states that the properties of the elements are periodic functions of their atomic number. This means that when elements are arranged in order of increasing atomic number, their physical and chemical properties exhibit a recurring pattern.

2. **Identifying the Options**: The question provides four options:
- Atomic number
- Electronic configuration
- Atomic mass
- Atomic size

3. **Analyzing Each Option**:
- **Atomic Number**: This is the number of protons in the nucleus of an atom and is the basis for the arrangement of elements in the periodic table. According to the modern periodic law, properties of elements are periodic functions of their atomic number.
- **Electronic Configuration**: This refers to the distribution of electrons in an atom's orbitals. The electronic configuration is directly related to the atomic number, as it determines how electrons are arranged around the nucleus. The periodic properties of elements are also influenced by their electronic configuration.
- **Atomic Mass**: While atomic mass was historically used in earlier periodic tables, it is not the basis for the modern periodic law. The modern periodic table is organized by atomic number, not atomic mass.
- **Atomic Size**: This refers to the size of an atom, which can vary among elements but is not a direct basis for the periodic law.

4. **Conclusion**: Based on the analysis, the correct answer is that the properties of the elements are periodic functions of their atomic number and electronic configuration. Therefore, the correct options are:
- Atomic number (Correct)
- Electronic configuration (Correct)
- Atomic mass (Incorrect)
- Atomic size (Incorrect)

**Final Answer**: The properties of the elements are periodic functions of their atomic number and electronic configuration.

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