CBSE Class 11 Modern Periodic Law And The Present Form Of The Periodic Table Detail And Preparation Downloads

The Modern Periodic Law governs the arrangement of elements based on their atomic numbers. Proposed by Glenn T. Seaborg in the mid-20th century, this law refined the earlier Periodic Table. The present form organizes elements in ascending order of atomic numbers, demonstrating their recurring chemical properties. This systematic arrangement highlights the periodicity of element properties, fostering a comprehensive understanding of their behavior. The current table, a cornerstone of chemistry, elegantly captures the intricate relationships among elements, guiding scientific exploration and innovation.

Modern Periodic Law and the Present Form of the Periodic Table – CBSE NCERT Download

What is Modern Periodic law?

The Modern Periodic Law is a principle that governs the arrangement of elements in the Periodic Table based on their increasing atomic numbers. This law, proposed by Glenn T. Seaborg in the mid-20th century, states that the physical and chemical properties of elements are a periodic function of their atomic numbers. In other words, elements with similar chemical properties recur at regular intervals when arranged in order of increasing atomic numbers. This arrangement provides a systematic and comprehensive understanding of the relationships among elements, forming the basis of the modern Periodic Table.

Modern Periodic Table 

The modern Periodic Table organizes chemical elements based on their increasing atomic numbers, aligning with the Modern Periodic Law. Introduced by Glenn T. Seaborg, this arrangement highlights the periodic recurrence of elements with similar properties. The table comprises rows (periods) and columns (groups/families), with each element's position determined by its atomic number. The table's structure reflects the electron configuration and facilitates the prediction of an element's properties. It's a fundamental tool in chemistry, aiding scientists in understanding and predicting the behavior of elements, fostering advancements in various scientific disciplines, and serving as a cornerstone in chemical education worldwide.

Classification of the Elements in the Periodic Table

The elements in the Periodic Table are classified based on their properties and electronic configurations. Here are the main classifications:

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1. Periods:

Elements are arranged in horizontal rows called periods.

Each period represents a different energy level or shell for electrons.

There are seven periods in the modern Periodic Table.

2. Groups/Families:

Elements are grouped into vertical columns called groups or families.

Elements in the same group have similar chemical properties due to the same number of valence electrons.

There are 18 groups in the modern Periodic Table.

3. Blocks:

Elements are categorized into blocks based on the subshell that receives the last electron in their electron configuration.

The blocks are s-block, p-block, d-block, and f-block.

• S-Block:

Includes groups 1 and 2, as well as helium in period 1.

Elements in this block have their outermost electrons in the s orbital.

•   P-Block:

Includes groups 13 to 18.

Elements in this block have their outermost electrons in the p orbital.

•  D-Block:

Includes transition metals, found in groups 3 to 12.

Elements in this block have their outermost electrons in the d orbital.

•   F-Block:

Includes lanthanides and actinides, placed separately at the bottom of the table.

Elements in this block have their outermost electrons in the f orbital.

4. Atomic Number Order:

  Elements are arranged in order of increasing atomic number.

5. Transition Metals:

Elements in groups 3-12 are transition metals, characterized by the filling of their d orbitals.

6. Noble Gases:

Group 18 consists of noble gases, which are chemically inert and have a full complement of electrons in their outermost shell.

Understanding these classifications helps scientists predict the properties and behaviors of elements, fostering a systematic approach to the study of chemistry

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SAMPLE PRACTICE QUESTIONS OF SIGNIFICANT FIGURES:

Q1. What is the genesis of periodic classification?

Answer. The genesis of periodic classification refers to the historical development and evolution of systematic arrangements of chemical elements based on their properties, leading to the creation of the periodic table.

Q2. What is Mendeleev's contribution to the periodic table?

Answer. Dmitri Mendeleev's major contribution was the creation of a periodic table that arranged elements based on their atomic masses, predicting the properties of undiscovered elements and leaving gaps for them in his table.

Q3. How has the periodic table evolved?

Answer. The periodic table has evolved with advancements in atomic theory and experimental techniques. It continues to be refined and expanded as new elements are discovered and our understanding of atomic structure deepens.

Q4. What role did atomic number play in the evolution of the periodic table?

Answer. The discovery of atomic numbers, later attributed to Henry Moseley, led to the modern periodic table. Elements were reorganized based on atomic number rather than atomic mass, providing a more accurate reflection of the periodicity of properties.

Q5. How does the Periodic Law play a role in the genesis of periodic classification?

Answer. The Periodic Law, formulated by Mendeleev, states that the properties of elements are a periodic function of their atomic masses. This principle guided the systematic arrangement of elements in the periodic table.

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