Define Modern Periodic law . .

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Concept**: The Modern Periodic Law is a fundamental principle in chemistry that describes the relationship between the properties of elements and their atomic structure.

2. **Definition**: The Modern Periodic Law states that the physical and chemical properties of elements are periodic functions of their atomic numbers. This means that when elements are arranged in order of increasing atomic number, elements with similar properties appear at regular intervals.

3. **Atomic Number**: The atomic number of an element is defined as the number of protons in the nucleus of an atom. It is a unique identifier for each element and determines its position in the periodic table.

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