61 public questions tagged with this topic.
Calcium (Ca) has the configuration [Ar] 4s² . Losing 2 electrons forms Ca²⁺ with a stable noble gas configuration [Ar] .
Ref: NCERT Class 11 Chemistry > Chapter 4: Chemical Bonding and Molecular Structure > Topic: Hydrogen Bonding and Resonance and Dipole Moment
Metalloids lie along the metal-non-metal boundary. Si (group 14) is a metalloid, while Na (group 1), Mg (group 2), and S (group 16) are not.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Periodic Trends - Atomic Radii Ionic Radii and Ionization Enthalpy
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
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
Fourth ionization enthalpy is highest for C (removing an electron from C³⁺ with 1s²) due to its small size and stable configuration, compared to Si, Ge, or Sn.
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 down a group due to increasing size. Among O, S, Se, and Te, Te (period 5) has the lowest value.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Nomenclature of Elements with Atomic Number >100
All group 15 elements can exhibit a +5 oxidation state, but N achieves it most prominently (e.g., in HNO₃) due to its small size and high electronegativity, unlike P, As, or Sb.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Nomenclature of Elements with Atomic Number >100
Pnictogens are group 15 elements. Sb (group 15) is a pnictogen, while Te (group 16), I (group 17), and Sn (group 14) are not.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Nomenclature of Elements with Atomic Number >100
In group 15, As is a metalloid, while N (non-metal), P (non-metal), and Bi (metal) are not.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Nomenclature of Elements with Atomic Number >100
Second period elements (Li to F) have only 2s and 2p orbitals, limiting covalency to 4. C (group 14) achieves this (e.g., CH₄), unlike Li, Be, or N.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Nomenclature of Elements with Atomic Number >100
The third period (n=3) includes 3s and 3p orbitals, accommodating 8 electrons, hence 8 elements (Na to Ar).
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Nomenclature of Elements with Atomic Number >100
Elements with Z > 100 have systematic IUPAC names until officially named. For 113: 1 (un), 1 (un), 3 (tri) → ununtrium. However, it’s now officially Nihonium (Nh).
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Nomenclature of Elements with Atomic Number >100
