Latest questions in this category.
s-block elements have outermost electrons in s-orbitals (groups 1 and 2). Na (group 1) is an s-block element, while B (group 13), Si (group 14), and P (group 15) are p-block elements.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
The +3 oxidation state becomes more stable down group 15 due to the inert pair effect. Bi forms stable BiCl₃ (+3), more so than N, P, or As, where +5 is also common.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
Solubility of group 2 hydroxides increases down the group due to decreasing lattice energy. Be(OH)2 has the lowest solubility due to Be’s small size and high charge density.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
d-block elements (groups 3–12) have electrons filling (n-1)d orbitals, with outer configuration (n-1)d¹⁻¹⁰ ns⁰⁻².
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
Group 16 trioxides (XO₃) show a +6 oxidation state. S forms SO₃, the most stable and common trioxide, unlike O, Se, or Te where XO₃ is less prevalent.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
d-block elements (groups 3–12) have electrons filling d-orbitals. Mn (group 7) is a d-block element, while Ga (p-block), Rb (s-block), and Kr (p-block) are not.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
Stability of group 17 oxides in high oxidation states increases down the group. I₂O₅ (I, +5) is the most stable, unlike F₂O, Cl₂O₇, or BrO₃.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
Covalent character (Fajans’ rule) increases with smaller size and higher charge density. NCl₃ (N, smallest) has the highest covalent character among N, P, As, and Sb trichlorides.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
The f-block in period 6 corresponds to the lanthanoids (4f), with 14 elements (Ce to Lu).
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
Transition elements (d-block, groups 3–12) have partially filled d-orbitals. Fe (group 8) is a transition element, while Na (s-block), Al (p-block), and Cs (s-block) are not.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
f-block elements have electrons filling f-orbitals (lanthanoids and actinoids). Ce (Z=58) is an f-block element, while Sc (d-block), Rb (s-block), and Xe (p-block) are not.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
Group 15 elements (N, P, As, etc.) form hydrides like NH₃. CH₄ (group 14), H₂O (group 16), and HCl (group 17) are from other groups.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
