Latest questions in this category.
Sixth ionization enthalpy peaks when removing an electron from a stable X⁵⁺ ion. Te (after losing five electrons, becomes Te⁵⁺ 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: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
Mendeleev predicted Eka-silicon below Si, later identified as Germanium (Ge), matching its properties like oxide formula GeO₂.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
This configuration (Z=23) corresponds to V (period 4, group 5), with 3d³ 4s², distinguishing it from Ti (3d² 4s²), Cr (3d⁵ 4s¹), or Mn (3d⁵ 4s²).
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
For isoelectronic species (10 electrons), ionic radius decreases with increasing nuclear charge. Al³⁺ (Z=13) has the lowest radius compared to Na+, Mg²⁺, or F⁻.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
Second ionization enthalpy is highest when removing an electron from a stable X+ ion. Na (after losing one electron, becomes Na+ with 1s² 2s² 2p⁶) has the highest value in period 3 compared to Mg, Si, or P.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
Lattice energy increases with smaller ionic radii (higher charge density). BeF₂ has the highest lattice energy in group 2 due to Be²⁺’s small size, compared to MgF₂, CaF₂, or SrF₂.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
Ionic character increases with larger cation size and lower polarizing power in group 2. BaF₂ (Ba²⁺, largest) has the highest ionic character among BeF₂, MgF₂, CaF₂, and BaF₂.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
Acidity of group 15 oxides increases with oxidation state and decreases down the group. N₂O₅ (N in +5) is the most acidic, forming HNO₃, unlike P₂O₅, As₂O₅, or Sb₂O₅.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
Electronegativity decreases down group 15 due to increasing size. Bi (period 6) has the lowest value among N, P, As, and Bi.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
In period 5 d-block (Y to Cd), Tc (group 7) achieves a +7 oxidation state (e.g., in Tc₂O₇) due to the availability of d-electrons, unlike Zr, Nb, or Mo.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
For isoelectronic species (36 electrons), lattice energy increases with charge. Sc³⁺ (Z=21, +3) forms ScF₃ with the highest lattice energy compared to K+, Ca²⁺, or Br⁻.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
This configuration (Z=28) corresponds to Ni (period 4, group 10), with 3d⁸ 4s², distinguishing it from Fe (3d⁶ 4s²), Co (3d⁷ 4s²), or Cu (3d¹⁰ 4s¹).
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev
