Core Reactions

Reaction with water (Group 1): 2M + $2H_{2}O$ --[room temp]--> 2MOH + $H_{2}$↑

Oxide type trend (excess $O_{2}$): Li + $O_{2}$ --[excess]--> $Li_{2}O$ Na + $O_{2}$ --[excess]--> $Na_{2}$$O_{2}$ K + $O_{2}$ --[excess]--> K$O_{2}$

Solvay process (key step): NaCl + $NH_{3}$ + C$O_{2}$ + $H_{2}$O --> $NaHCO_{3}$↓ + $NH_{4}Cl$ 2$NaHCO_{3}$ --[$\Delta$]--> $Na_{2}$$CO_{3}$ + C$O_{2}$↑ + $H_{2}$O

NaOH manufacture (chlor-alkali): 2NaCl + $2H_{2}O$ --[electrolysis]--> 2NaOH + $Cl_{2}$↑ + $H_{2}$↑

Whitewashing reaction: Ca(OH)_{2} + C$O_{2}$ --> Ca$CO_{3}$↓ + $H_{2}$O

Bleaching powder preparation: Ca(OH)_{2} + $Cl_{2}$ --> CaO$Cl_{2}$ + $H_{2}$O

Plaster of Paris manufacture: $2CaSO_{4}$·$2H_{2}O$ --[373 K]--> $2CaSO_{4}$·½$H_{2}$O + 3$H_{2}$O

Plaster of Paris setting: $CaSO_{4}$·½$H_{2}$O + 3/$2H_{2}O$ --> $CaSO_{4}$·$2H_{2}O$ (gypsum, exothermic)

Limestone calcination: Ca$CO_{3}$ --[1073 K]--> CaO + C$O_{2}$↑

Key Numerical Data

$IE_1(\text{Li}) = 520 \text{ kJ/mol},\quad IE_1(\text{Na}) = 496,\quad IE_1(\text{K}) = 419,\quad IE_1(\text{Cs}) = 376 \text{ kJ/mol}$

$E^\circ(\text{Li}^+/\text{Li}) = -3.04\text{ V}\quad (\text{most negative in Group 1 — highest reducing power in aqueous solution})$

Ionic radii trend (pm): $Li^{+}$ (76) < $Na^{+}$ (102) < $K^{+}$ (138) < $Rb^{+}$ (152) < $Cs^{+}$ (167) ↑

Hydration enthalpy trend (kJ/mol): $Li^{+}$ (−520) > $Na^{+}$ (−406) > $K^{+}$ (−322) > $Cs^{+}$ (−276) ↓ (most negative = most hydrated)

Formula Summary Table