Group 2 — Alkaline earth metals, trends
s-block Elements
5
JEE Qs
8%
Hard
75
min
Focus on understanding the periodic trends in physical and chemical properties, the anomalous behavior of beryllium, and the specific solubility/thermal stability trends of various compounds to tackle comparison-based questions effectively.
🧮 Key Formulas
✅ Key Points for JEE
- 1**Periodic Trends**: Atomic/ionic radii, metallic character, and reducing nature increase down the group. Ionization enthalpy, electronegativity, and polarizing power decrease down the group. Be has the highest ionization energy and smallest size.
- 2**Anomalous Behavior of Beryllium**: Due to its exceptionally small size, high charge density, and absence of d-orbitals, Be forms predominantly covalent compounds, its oxide/hydroxide are amphoteric, and it exhibits a diagonal relationship with Aluminium (e.g., forming Be2C and Al4C3, having similar polarizing power).
- 3**Solubility and Thermal Stability**: Solubility of hydroxides M(OH)2 increases down the group (increasing basicity). Solubility of sulfates MSO4 decreases down the group. Thermal stability of carbonates MCO3 and nitrates M(NO3)2 increases down the group (decomposition temperature increases).
- 4**Reactivity and Reducing Character**: Alkaline earth metals are strong reducing agents; their reducing power increases down the group. They react with water (except Be), halogens, hydrogen, and acids.
- 5**Flame Coloration**: Ca, Sr, Ba impart characteristic colors (brick red, crimson, apple green respectively) to an oxidizing flame due to electron excitation. Be and Mg do not give flame tests because their high ionization enthalpies require too much energy to excite electrons into higher energy states.
⚠️ Common Mistakes
- ✕Confusing the solubility trends: M(OH)2 solubility increases down the group, while MSO4 solubility decreases down the group.
- ✕Forgetting that BeO and Be(OH)2 are amphoteric, unlike other Group 2 oxides/hydroxides which are basic.
- ✕Incorrectly assuming all Group 2 metals give flame tests; Be and Mg do not due to high ionization energies.
📝 Practice Questions
See allQ49. List - I List - II Reaction Type of redox reaction (A) Li (I) 589.2 Match List - I with List - II. Choose the correct answer from the options (B) Na (II) 455.5 (C) Rb (III) 670.8 (D) Cs (IV) 780.0 given below : (1) (A)-(II), (B)-(IV), (C)-(III), (D)-(I) (2) (A)-(I), (B)-(IV), (C)-(III), (D)-(II) (3) (A)-(IV), (B)-(II), (C)-(I), (D)-(III) (4) (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
Q40.Ion having highest hydration enthalpy among the given alkaline earth metal ions is: (1) Be2+ (2) Sr2+ (3) Ba2+ (4) Ca2+
Q32.Match List I with List II (A) Slaked lime (I) NaOH (B) Dead burnt plaster (II) Ca ( OH ) 2 (C) Caustic soda (III) Na2CO3 · 10H2O (D) Washing soda (IV) CaSO4 Choose the correct answer form the options given below: (1) (A) - I, (B) - IV, (C) - II, (D) - III (2) (A) - III, (B) - IV, (C) - II, (D) - I (3) (A) - II, (B) - IV, (C) - I, (D) - III (4) (A) - III, (B) - II, (C) -IV, (D) -I
Q33.Choose the correct statement(s): A. Beryllium oxide is purely acidic in nature. B. Beryllium carbonate is kept in the atmosphere of CO2. C. Beryllium sulphate is readily soluble in water. D. Beryllium shows anomalous behavior. Choose the correct answer from the options given below: JEE Main 2023 (01 Feb Shift 1) JEE Main Previous Year Paper (1) A, B and C only (2) B,C and D only (3) A and B only (4) A only
Q40.The correct order of bond enthalpy ( kJ mol–1 ) is: (1) Si −Si > C −C > Sn −Sn > Ge −Ge (2) Si −Si > C −C > Ge −Ge > Sn −Sn (3) C −C > Si −Si > Sn −Sn > Ge −Ge (4) C −C > Si −Si > Ge −Ge > Sn −Sn
Q37. O −O bond length in H2O2 is X than the O −O bond length in F2O2 . The O −H bond length in H2O2 is Y ¯¯ than that of the O −F bond in F2O2 . Choose the correct option for X and Y from the given below. ¯¯ (1) X - shorter, Y− shorter (2) X -shorter, Y -longer (3) X -longer, Y -longer (4) X-longer, Y - shorter
NCERT Chapters
- Class 11 Chemistry Ch 10: The s-Block Elements