Who proposed the Modern Periodic Law, and what is the physical basis for it?

📚 Chapter: Classification of Elements and Periodicity in Properties

📘 Answer with Explanation

🔵 Step 1: Who proposed the Modern Periodic Law?

The Modern Periodic Law was proposed by Henry Moseley in 1913.

"The physical and chemical properties of elements are periodic functions of their atomic numbers."

🟢 Step 2: What is the physical basis?

The physical basis of the Modern Periodic Law is the atomic number (Z) of an element.

Atomic number represents the number of protons present in the nucleus of an atom. In a neutral atom, it is also equal to the number of electrons.

Z = Number of protons = Number of electrons

🟣 Step 3: Why is atomic number important?

The atomic number determines the electronic configuration of an element. The electronic configuration, particularly the arrangement of valence electrons, determines the chemical properties of the element.

Atomic Number → Electronic Configuration → Chemical Properties

🎬 3D-Style Atomic Number Animation

Increasing atomic number means an increase in the number of protons and, for a neutral atom, electrons.

Z=1 Z=2 Z=3 Z=4 Z=5

Atomic Number increases → Periodic properties repeat

✅ Final Answer

Henry Moseley proposed the Modern Periodic Law in 1913.

The physical basis of the Modern Periodic Law is atomic number and the corresponding electronic configuration of elements.

🎯 Exam Point

Modern Periodic Law → Henry Moseley → 1913

Basis → Atomic Number (Z)

Atomic Number → Electronic Configuration → Properties