Nitrogen Group Elements and Transition Metals Properties

Group 15 Elements (Nitrogen Family)

The nitrogen family (Group 15) includes Nitrogen (N), Phosphorus (P), Arsenic (As), Antimony (Sb), and Bismuth (Bi).

Physical Properties

• Allotropy: Phosphorus, Arsenic, and Antimony exhibit allotropy.
• Phosphorus: White phosphorus is highly active, while other forms are relatively inactive.

Oxides of Nitrogen

• N₂O: Nitrous oxide (laughing gas).
• NO: Nitric oxide (paramagnetic).
• NO₂: Nitrogen dioxide.
• N₂O₄: Dinitrogen tetroxide (diamagnetic).

Ammonia and Nitric Acid

Ammonia (NH₃) reacts with water to form ammonium hydroxide (NH₄OH). Nitric acid (HNO₃) is produced via the Ostwald process using a platinum catalyst.

Nitric Acid Properties

• Commercial HNO₃ (~15M) often appears yellow due to dissolved nitrogen oxides.
• It acts as a powerful oxidizing agent.
• Reactions with metals: Dilute HNO₃ reacts with active metals to produce hydrogen, while concentrated HNO₃ typically produces nitrogen oxides.
• Reactions with non-metals: Concentrated HNO₃ oxidizes non-metals into their respective oxoacids.

Transition Metals

Key features include incomplete d-subshells, compact atomic packing, small atomic radii, and strong metallic bonding, resulting in high density and high melting points.

• Properties: Most ions are colored, paramagnetic, act as Lewis acids, and function as excellent catalysts.
• Common Elements: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu.

Chromium (Cr)

Electron configuration: [Ar] 3d⁵4s¹. Common oxidation states: +2, +3, +6.

• Cr²⁺: Acts as a strong reducing agent.
• Dichromate (Cr₂O₇^2-): A powerful oxidizing agent.
• pH Dependence: The equilibrium between chromate (CrO₄^2-) and dichromate (Cr₂O₇^2-) depends on the pH of the solution.
• Applications: Used in stainless steel production and protective chrome plating.

Manganese (Mn)

Electron configuration: [Ar] 3d⁵4s². Known mineral: Pyrolusite (MnO₂).

• Oxidation States: Ranges from +2 to +7.
• MnO₂ (+4): Used in batteries.
• Permanganate (MnO₄^-, +7): A powerful oxidizing agent in both acidic and basic media.