39 public questions tagged with this topic.
5f orbitals shield less effectively than 4f orbitals, increasing effective nuclear charge and contraction in actinoids. This follows from NCERT principle where relation explains outcome clearly for students.
Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: d and f Block Elements, Topic: Lanthanoid contraction due to poor shielding of 4f orbitals.
The 4f orbitals have poor shielding due to their radial distribution, causing a greater effective nuclear charge and size reduction across the lanthanoids.
Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.
Gradual decrease in atomic/ionic radii of lanthanoids due to poor shielding by 4f electrons.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Lanthanoids - Electronic Configuration and Lanthanoid Contraction
Lanthanoid contraction compensates for the expected increase in size from Zr to Hf.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: General Properties of d-Block - Electronic Configuration and Trends
Atomic radius increases down a group due to additional electron shells. For group 2: Be < Mg < Ca.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
First ionization enthalpy increases across a period. Among Na, Mg, Si, and Ar, Ar (group 18, period 3) has the highest value due to its stable noble gas configuration.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
In group 13, Ga and In have a smaller ionization enthalpy difference due to d-block contraction effects, unlike B-Al, where the drop is larger due to a new shell.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
Second ionization enthalpy is highest when removing an electron from a stable configuration. Na (after losing one electron, becomes Na+ with noble gas configuration) has the highest value compared to Mg, Al, or Si.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
Third ionization enthalpy peaks when removing an electron from a noble gas-like X²⁺ ion. Mg (after losing two electrons, becomes Mg²⁺ with 1s² 2s² 2p⁶) has the highest value.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
Second ionization enthalpy peaks when removing an electron from a stable X+ ion. Rb (after losing one electron, becomes Rb+ with 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶) has the highest value in period 5.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
First ionization enthalpy increases across a period due to increasing nuclear charge and decreases down a group due to increased shielding. Among Li, Be, Na, and Mg, Be (second period, group 2) has the highest value due to its stable 2s² configuration.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
First ionization enthalpy generally increases across period 2, but N (half-filled 2p³) has higher stability than O. Order: B < C < O < N.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
