5 public questions tagged with this topic.
Third ionization enthalpy peaks when removing an electron from a noble gas-like X²⁺ ion. Sr (after losing two electrons, becomes Sr²⁺ 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
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 decreases across a period from right to left. In period 5, Rb (group 1) has the lowest value compared to Sr, Ag, and I.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
The fifth period (n=5) includes 5s (2 electrons), 4d (10 electrons), and 5p (6 electrons), totaling 18 electrons.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Nomenclature of Elements with Atomic Number >100
In period 5 p-block (Rb to Xe), electronegativity increases across. I (group 17) has the highest electronegativity among Sn, Sb, and I, excluding noble gases.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Electron Gain Enthalpy and Electronegativity and Valency
