Periodicity 02 Class Notes - Target IIT JAM 2025 PDF

# TARGET - IIT JAM 2025 ## Concept & Questions ### Periodicity #### Lecture - 02 #### By - Hitesh Chugh Sir # Recap of previous lecture 1. Borazine # TOPICS to be covered 1. Periodicity: Concepts & Question * Quantum No. * Modern Periodic Table. * Size * E.A * OEN # The total...

# TARGET - IIT JAM 2025 ## Concept & Questions ### Periodicity #### Lecture - 02 #### By - Hitesh Chugh Sir # Recap of previous lecture 1. Borazine # TOPICS to be covered 1. Periodicity: Concepts & Question * Quantum No. * Modern Periodic Table. * Size * E.A * OEN # The total number of orbital present in a shell whose principle quantum number is 4. - (a) 32 - (b) 4 - (c) 9 - (d) 16 **Answer:** 16 **Explanation:** * n = 4 * l = 0 to n - 1 = 0, 1, 2, 3 * No of orbitale in a shell = n² = (4)² = 16 # Which of the following set of quantum number is correct for an electron in 4d orbital - (a) n = 4, l = 2, m = 1, s = 1/2 - (b) n = 4, l = 3, m = 3, s = -1/2 - (c) n = 3, l = 3, m = 3, s = -1/2 - (d) n = 4, l = 2, m = 3, s = 1/2 **Answer:** (b) n = 4, l = 3, m = 3, s = -1/2 **Explanation:** * n = Principal Quantum Number = Shell number = 4 * l= Azimuthal Quantum Number = Subshell = 2 (for d) * m = Magnetic Quantum Number = Orbital = -l to + l = -2, -1, 0, 1, 2 * s = Spin Quantum Number = ±1/2 # Which among the following is not in accordance with aufbau's principle- - (a) 5f < 6d < 7s < 7p - (b) 7s < 5f < 6d < 7p - (c) 3d < 4p < 5s < 4d - (d) 6s < 4f < 5d < 6p **Answer:** (a) 5f < 6d < 7s < 7p **Explanation:** * **n + l Rule:** According to the Aufbau principle, the lower the value of (n + l), the lower the energy of the orbital and it will get filled first. * **n Rule:** If (n + l) values are the same, then check for the lower value of n. # Be B C N Size des. ## The correct order of radii is- - (a) N > Be > B - (b) F- < O²- <N³ - (c) Na<Li<K - (d) Fe³⁺ < Fe²⁺ <Fe⁴⁺ **Answer:** (c) Na<Li<K **Explanation:** * **Ionic Radii:** In general, ionic radii increase as you move down a group in the periodic table and decrease as you move across a period. * **I.R & the charge α 1 / tue chary** # IE2 Be > IE2 B ## Amongst the following, incorrect order is - - (a) IE2 (Be) > IE2 (B) - (b) IE2(Na) > IE2(Mg) - (c) IE2 (Mg) > IE2 (Be) - (d) IE2 (N) > IE2 (O) **Answer:** (c) IE2 (Mg) > IE2 (Be) **Explanation:** * IE2 is higher for Be than Mg because of the half-filled electronic configuration of Be. * Stable E-C (Be) > stable E-C (B) # The electrons, identified by quantum numbers n and l ## can be placed in order of increasing energy, from the lowest to highest, as - (i) n = 4, l = 1, - n+l = 4+1 = 5 - (ii) n = 4, l = 0, - n+l = 4+0 = 4 - (iii) n = 3, l = 2 -n+l = 3+2 = 5 - (iv) n = 3, l = 1 n+l = 3+1 = 4 - A (iv) < (ii) < (iii) < (i) - B (ii) < (iv) < (i) < (iii) - C (i) < (iii) < (ii) < (iv) - D (iii) < (i) < (iv) < (ii) **Answer:** B (ii) < (iv) < (i) < (iii) **Explanation:** * n + l Rule: The ordering is as follows - (ii) < (iv) < (i) < (iii) # The numbers of radial nodes, planar angular nodes and non-planar angular nodes in 3d_z², 3s and 3p_x orbitals are - (a) (0, 0, 2), (2, 0, 0), (1, 1, 0) respectively - (b) (0, 2, 0), (2, 0, 0), (1, 1, 0) respectively - (c) (2, 0, 0), (2, 0, 0), (0, 1, 1) respectively - (d) (0, 2, 0), (0, 2, 0), (1, 1, 0) respectively **Answer:** (a) (0, 0, 2), (2, 0, 0), (1, 1, 0) respectively **Explanation:** * **Radial Nodes:** n - l - 1 * **Angular Nodes:** l # **Which of the following statement(s) about spectral series is incorrect?** - 1. Paschen series appears in the infrared region - 2. The lines in the Balmer series corresponds to electron transitions from energy levels higher than n = 2 energy level. - 3. Transitions from higher energy levels to 5th energy level produce P-fund series which falls in the infrared region - 4. The lines of Lyman series appear in the visible region **Answer:** 4. The lines of Lyman series appear in the visible region **Explanation:** * **Lyman series:** n = 1 to higher energy levels (UV region) * **Balmer series:** n = 2 to higher energy levels (Visible region) * **Paschen series:** n = 3 to higher energy levels (IR region) * **Brackett series:** n = 4 to higher energy levels (IR region) * **Pfund series:** n = 5 to higher energy levels (IR region) # Which one will have the highest 2nd ionisation energy? - (A) 1s²2s²2p⁶3s¹ - (B) 1s²2s²2p⁴ - (C) 1s²2s²2p⁶ - (D) 1s²2s²2p⁶3s² **Answer:** (A) 1s²2s²2p⁶3s¹ **Explanation:** * The second ionization energy is the energy required to remove the second electron from the atom. In option A, the second electron will be removed from a stable, completely filled p shell, making it more difficult to remove. # For Na+, Mg²⁺> Na⁺>F⁻, the CORRECT order of ionic radii is ## [IIT JAM 2021] - A Al³⁺> Mg²⁺>Na⁺> F⁻ - B Al³⁺> Na⁺>Mg²⁺> F⁻ - C F⁻> Na⁺>Mg²⁺> Al³⁺ - D Na⁺>F⁻>Mg²⁺> Al³⁺ **Answer:** C F⁻> Na⁺>Mg²⁺> Al³⁺ **Explanation:** * **Ionic radii** increase as you move down a group and decrease as you move across a period. * **Z_eff** (Effective Nuclear Charge) is the net positive charge experienced by an electron in an atom. Higher Z_eff leads to a smaller ionic radius. * The larger the charge on the ion, the smaller the ionic radius. # With respect to periodic properties, the CORRECT statement is ## [IIT JAM 2018] - (a) Electron affinity order is F > O > Cl - (b) First ionisation energy order is Al > Mg > K - (c) Atomic radius order is N > P > As - (d) Ionic radius order is K⁺> Ca²⁺> Mg²⁺ **Answer:** (d) Ionic radius order is K⁺> Ca²⁺> Mg²⁺ **Explanation:** * **Electron affinity** is the change in energy that occurs when an electron is added to a neutral atom to form a negative ion. Electron affinity generally increases from left to right across a period and decreases down a group, however, there are some exceptions. * **First ionization energy** is the minimum energy required to remove the most loosely bound electron from a neutral gaseous atom in its ground state. First ionization energy generally increases from left to right across a period, and decreases as you move down a group. * **Atomic radius** is a measure of the size of an atom. Atomic radius decreases from left to right across a period and increases as you move down a group. * **Ionic radius:** is the size of an ion. In general, ionic radii increase as you move down a group in the periodic table and decrease as you move across a period. Larger ionic radii generally correlate with a lower Z_eff. # The correct statement about ionization potential (IP) is [IIT JAM 2015] - (a) Non-metallic character of an element decreases as the IP increases - (b) IP decreases down the group in the periodic table - (c) Second IP of Ca is larger than second IP of K - (d) IP decreases on going from left to right in the periodic table **Answer:** (b) IP decreases down the group in the periodic table **Explanation:** * **Ionization potential (IP):** The amount of energy required to remove the most loosely bound electron from a neutral isolated gaseous atom in its electronic ground state. * **IP α Z_eff/ (T_eff)² α Metallic character** * **IP α 1/ size or atomic radius**