CBSE Class 10 Science Notes & Important Questions Chapter 5 Periodic Classification of Elements

CBSE Class 10 Science Notes & Important Questions Chapter 5 Periodic Classification of Elements

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CBSE Class 10 Science Notes & Important Questions Chapter 5 Periodic Classification of Elements

CBSE Class 10 Science Notes & Important Questions Chapter 5 Periodic Classification of Elements

Chapter 5: Periodic Classification of Elements

Introduction:

  • The discovery of a large number of elements and their various properties made it difficult to study and remember them individually.
  • This led to the development of periodic table by Dmitri Mendeleev and Lothar Meyer.
  • The periodic table is a tabular arrangement of all the known elements in order of their atomic number.

Mendeleev’s Periodic Table:

  • Dmitri Mendeleev, a Russian chemist, was the first to arrange the elements in the periodic table.
  • Mendeleev arranged the elements in order of increasing atomic masses and according to their chemical and physical properties.
  • He left gaps for undiscovered elements and predicted their properties.

Modern Periodic Table:

  • The modern periodic table is based on the atomic number of the elements.
  • It is arranged in horizontal rows called periods and vertical columns called groups.
  • The elements in a group have similar chemical and physical properties.
  • The periodic table is divided into four blocks: s-block, p-block, d-block, and f-block.

Electronic Configuration:

  • The arrangement of electrons in the shells of an atom is called its electronic configuration.
  • The electronic configuration of an element determines its chemical and physical properties.
  • Elements in the same group have the same number of valence electrons and similar electronic configurations.

Trends in the Modern Periodic Table:

  • Atomic size increases down a group and decreases across a period.
  • Ionization energy increases across a period and decreases down a group.
  • Electronegativity increases across a period and decreases down a group.
  • Metallic character increases down a group and decreases across a period.

Conclusion:

  • The periodic table is an important tool for studying and understanding the properties of elements.
  • It helps in predicting the properties of new elements and in developing new materials and compounds.

Some Important Questions

  1. What is the periodic table and who developed it?
  2. How is the modern periodic table arranged?
  3. What are the different blocks in the periodic table and what are their properties?
  4. How is the electronic configuration of an element related to its position in the periodic table?
  5. What are the trends in the periodic table for atomic size, ionization energy, electronegativity, and metallic character?
  6. How can the periodic table be used to predict the properties of new elements?
  7. What is the significance of the periodic table in chemistry?
  8. How did Mendeleev arrange the elements in his periodic table?
  9. Why are the elements in the same group in the periodic table said to have similar chemical properties?
  10. How did the discovery of new elements influence the development of the periodic table?
  1. What is the periodic table and who developed it?

The periodic table is a tabular arrangement of all the known elements in order of their atomic number. It was developed by Dmitri Mendeleev and Lothar Meyer.

  1. How is the modern periodic table arranged?

The modern periodic table is arranged in horizontal rows called periods and vertical columns called groups. The elements in a group have similar chemical and physical properties.

  1. What are the different blocks in the periodic table and what are their properties?

The periodic table is divided into four blocks: s-block, p-block, d-block, and f-block. The s-block elements are metals with low melting and boiling points, the p-block elements are non-metals or metalloids, the d-block elements are metals with high melting and boiling points, and the f-block elements are lanthanides and actinides.

  1. How is the electronic configuration of an element related to its position in the periodic table?

The electronic configuration of an element determines its chemical and physical properties. Elements in the same group have the same number of valence electrons and similar electronic configurations.

  1. What are the trends in the periodic table for atomic size, ionization energy, electronegativity, and metallic character?

Atomic size increases down a group and decreases across a period. Ionization energy increases across a period and decreases down a group. Electronegativity increases across a period and decreases down a group. Metallic character increases down a group and decreases across a period.

  1. How can the periodic table be used to predict the properties of new elements?

The periodic table can be used to predict the properties of new elements by examining the properties of elements in the same group and period. The position of an element in the periodic table can give information about its electronic configuration, valence electrons, and reactivity.

  1. What is the significance of the periodic table in chemistry?

The periodic table is an important tool for studying and understanding the properties of elements. It helps in predicting the properties of new elements and in developing new materials and compounds.

  1. How did Mendeleev arrange the elements in his periodic table?

Mendeleev arranged the elements in order of increasing atomic masses and according to their chemical and physical properties. He left gaps for undiscovered elements and predicted their properties.

  1. Why are the elements in the same group in the periodic table said to have similar chemical properties?

Elements in the same group have the same number of valence electrons and similar electronic configurations. This makes them have similar chemical properties.

  1. How did the discovery of new elements influence the development of the periodic table?

The discovery of new elements challenged the existing periodic table and led to the development of new versions with more accurate predictions. It also led to the discovery of new trends and properties of elements.

Some MCQS Related to The Topics

  1. The horizontal rows in the modern periodic table are called: a) periods b) groups c) blocks d) families

Answer: a) periods

  1. The vertical columns in the modern periodic table are called: a) periods b) groups c) blocks d) families

Answer: b) groups

  1. Which of the following blocks in the periodic table includes elements with the highest ionization energies? a) s-block b) p-block c) d-block d) f-block

Answer: c) d-block

  1. The trend in the periodic table for atomic size is: a) increases down a group and increases across a period b) increases down a group and decreases across a period c) decreases down a group and increases across a period d) decreases down a group and decreases across a period

Answer: b) increases down a group and decreases across a period

  1. Which element has the highest electronegativity? a) Fluorine b) Oxygen c) Nitrogen d) Carbon

Answer: a) Fluorine

  1. Which of the following elements is a metalloid? a) Boron b) Nitrogen c) Oxygen d) Fluorine

Answer: a) Boron

  1. What is the group number and period number for the element sodium (Na)? a) Group 1, Period 2 b) Group 2, Period 1 c) Group 1, Period 3 d) Group 3, Period 1

Answer: a) Group 1, Period 2

  1. Which of the following elements is a noble gas? a) Helium b) Chlorine c) Sodium d) Calcium

Answer: a) Helium

  1. The elements in the same group have the same number of: a) electrons b) neutrons c) protons d) valence electrons

Answer: d) valence electrons

  1. The modern periodic law states that the properties of elements are a periodic function of their: a) atomic mass b) atomic number c) atomic weight d) atomic radius

Answer: b) atomic number

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