Properties of Alkali Metals (Group 1A)

Alkali Metals (Group 1A)

• Have 1 valence electron, which they lose to form a +1 oxidation state, making them reducing agents
• Electropositive, with weak metallic bonds due to their single valence electron
• Have large radii, small electron affinities, low first ionization energies, and low electronegativities
• Form ionic compounds

Compounds of Alkali Metals

• Potassium superoxide (KO2) is used to purify air, taking in CO2 and producing O2
• Peroxides and superoxides are oxidizing agents, reacting with water or acid to produce O2
• Alkali hydrides are reducing agents, reacting with water or acid to produce H2
• Alkali nitrates decompose, such as potassium nitrate (salt peter)
• Sodium nitrate is hygroscopic, absorbing water vapor from the air

Industrial Preparation of Sodium Carbonate (Na2CO3)

• Used to remove water hardness by precipitating Mg and Ca ions
• Prepared through the Solvay process: NaCl + CO2 + H2O + NH3 → NH4Cl + NaHCO3
• NaHCO3 is then heated to produce Na2CO3 + H2O + CO2
• NaOH is used to remove CO2, Cu to remove oxygen, H2SO4 to dehydrate water, and Hg to collect nitrogen

Ammonia (NH3)

• Prepared in the lab: 2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3
• Alternatively, prepared industrially: NH3 + LiOH → LiNH2 + H2O
• Colorless, lighter than air, dissolves in water, and has a high boiling point due to hydrogen bonds
• A base, turning blue litmus paper red, and reacts with acids to form ammonium salts
• Anhydrous NH3 is prepared by reacting nitrogen with lithium: Li + N2 → Li3N + H2O

Haber-Bosch Process

• Used to produce ammonia on a large scale: N2 + H2 → 2NH3
• Calcium cyanamide (CaCN2) is also used in this process

Alkali Metals (Group 1A)

• Valence electron: 1, loses 1 electron to form +1 oxidation state
• Reducing agent, electropositive (Na+)
• Weak metallic bond due to 1 valence electron
• Large radius, small electron affinity, low first ionization, and low electronegativity

Compounds of Alkali Metals

• Potassium superoxide (KO2): used to purify air, takes CO2 and produces O2
• Peroxides and superoxides: oxidizing agents, react with water or acid to produce O2
• Alkali hydrides: reducing agents, react with water or acid to produce H2
• Alkali nitrates: decompose (e.g., potassium nitrate, salt peter)

Sodium Compounds

• Sodium nitrate: hygroscopic, absorbs water vapor from air
• Sodium carbonate (Na2CO3): used to remove water hardness by precipitating Mg and Ca, industrially prepared by Solvay process
• Sodium hydroxide (NaOH): used to remove CO2, Cu is used to remove oxygen, H2SO4 is used to dehydrate water, and Hg is used to collect nitrogen

Ammonia

• Prepared from nitrogen: industrial preparation involves NH3CI + NaNO2, lab preparation involves 2NH4Cl + Ca(OH)2
• Properties: colorless, lighter than air, dissolves in water, polar, high boiling point due to hydrogen bonds
• Reacts with acids to form ammonium (NH4+), turns blue litmus paper to red
• Uses: anhydride, Haber-Bosch process, and CaCN2 reaction