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4. Nitrogéncsoport, széncsoport

2017.01.07

Inorganic Chemistry

Group V. and Group IV.

 

 

Members of the group:

  • Nitrogen
  • Phosphor

 

Nitrogen (N2)

Structure

  • 5 electrons on the outer shell (2 paired, 3 unpaired)
  • Diatomic molecule, triple bond

Physical properties

  • Odourless, colourless gas, slightly soluble in water

Chemical properties

  • Nonreactive in normal conditions
  • Lightning (3000 oC): reacts with oxygen

Occurence

  • Atmosphere (78%)
  • Compounds

 

Ammonia (NH3)

Physical properties

  • Colourless gas with a pungent smell
  • Soluble in water (1 l water dissolves 700 l ammonia at room temperature)
  • NH3 + H2O = NH4+ + OH-

Chemical properties

  • NH3 + HCl = NH4Cl

Production:

  • N2 + 3H2 = 2NH3

Importance:

  • Nitric acid, explosive, fertilizer, medicine, dye, plastic producing
  • In refrigerators: chilles when evaporates

 

 

Nitric acid (HNO3)

Physical properties

  • Colourless liquid with a pungent smell
  • Stored in dark bottle (decomposes to NO2)
  • Soluble in water:
  • HNO3 + H2O = NO3- + H3O+ (nitrate ion)

Chemical properties

  • Dilute nitric acid: Zn, Fe are dissolved, but Cu is not
  • Concentrated nitric acid: Cu is dissolved, but Fe is not (passive layer on the surface)
  • Oxidating agent
  • Választóvíz: az ezüstöt oldja, aranyat nem
  • Királyvíz: salétromsav, sósav 1:3 elegye, ez oldja az aranyat is
  • Yellow colour with proteins
  • HNO3 + NH3 = NH4+ + NO3-

Occurence

  • Compounds: nitrates

Importance:

  • Explosive, fertilizer, medicine, dye, plastic producing

 

Phosphorus (P)

Two allotropes:

 

 

White

Red

Physical properties

Yellow-white, soft, solid, insoluble in water, soluble in toluene, oils, fats

Red dust, insoluble in water, toluene, oils, fats

Chemical properties

Flammable at 60oC

 Flammable at 400oC

Poisonous

Not poisonous

 

Occurence

  • Only in compounds: guano, volcanic stones

Importance:

  • Match industry

 

Phosphoric acid (H3PO4)

Physical properties

  • Colourless crystal with low melting point
  • Soluble in water
  • H3PO4 +3H2O = 3H3O+ + PO43-
  • Weak acid

Use

  • In dilute solution it is not poisonous, used in soft drinks, preservative as food additive

Phosphates:

  • Trisodium phosphate Na3PO4 („water softener” in detergents)
  • In bones: Tricalcium diphosphate Ca3(PO4)2

 

 

 

Group IV.

 

 

Members of the group:

  • Carbon
  • (Silicon: metalloid)

 

Carbon (C)

Structure

  • Four unpaired electrons – 4 strong covalent bondings
  • Allotropes: diamond, graphite, fullerene

Chemical properties

  • C + O2 = CO2
  • 2C + O2 = 2CO (less oxygen)
  • Fe2O3 + 3C = 2Fe + 3CO reductive agent in iron production

Occurence

  • Elementary state: diamond, graphite, fullerene
  • Compounds: oxides, carbonates
  • Coal, charcoal

Importance:

  • Diamond: jewellery, drills
  • Graphite: pencils, lubricant, brushes in electric motors, neutron moderator

 

Carbon monoxide (CO)

Physical properties

  • Colourless, odourless gas
  • Poisonous

Chemical properties

  • 2CO + O2 = 2CO2
  • Fe2O3 + 3CO = 2Fe + 3CO2

 

 

Carbon dioxide (CO2)

Structure

  • Rodlike molecule, 2 double bonds

Physical properties

  • Colourless, odorless gas
  • Heavier than air
  • Soluble in water:
  • CO2 + H2O = H2CO3

Importance: chilling, beverages, mineral water

 

 

Carbonic acid (H2CO3)

  • Instable: decomposes to water and carbon dioxide
  • Soluble in water:
  • H2CO3 + 2H2O = 2H3O+ + CO32-   carbonate ion

Occurence:

  • Volcanic gases, spring water
  • Compounds: carbonates (limestone, dolomite)

 

 

Silicon (Si)

Physical properties

  • Shiny grey cristals
  • Hard, melting point is high
  • Semiconductor (conductivity depends on circumstances)

Occurence:

  • In minerals, rocks
  • Compounds: quartz, silicates

Use: transistors, solar cells, computers

 

Quartz (SiO2)

  • Hard, transparent crystals with high melting point
  • Occurence, importance: jewellery, sand, glass production