5 public questions tagged with this topic.
Fourth ionization enthalpy peaks when removing an electron from a stable X³⁺ ion. Si (after losing three electrons, becomes Si³⁺ 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
Fifth ionization enthalpy peaks when removing an electron from a stable X⁴⁺ ion. P (after losing four electrons, becomes P⁴⁺ with 1s² 2s² 2p⁶) has the highest value in period 4.
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 period 4 d-block (Sc to Zn), ionization enthalpy increases across due to increasing nuclear charge, with Zn (3d¹⁰ 4s²) having the highest due to its full d-subshell stability.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
Metallic character decreases across a period and increases down a group. In period 4, K (group 1) has the highest metallic character compared to Ca, Sc, or Ti.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
Electronegativity increases across a period. In period 4 (K to Kr), Br (group 17) has the highest electronegativity among K, Ca, and Br.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Electronic Configuration and Types of Elements - s p d f Blocks
