Ugrás a tartalomhoz Lépj a menübe
 


06 Nemesgázok, hidrogén, halogének

2016.02.08

Inorganic Chemistry

 

Classification, Noble Gases, Hydrogen, Halogens

 

Elements

Three main groups:

Metals:

  • Group I-IV and the d-block
  • 1,2,3 electrons on the outer shell
  • Most of them is solid at room temperature (except mercury)
  • Shiny grey (gold: yellow, copper: reddish brown)
  • Conduct electricity and heat
  • Melleable and ductile

Nonmetals:

  • Group IV – VIII
  • 4,5,6,7,8 electrons on the outer shell (Hydrogen: 1, Helium: 2)
  • Gas (hydrogen, oxygen, nitrogen, chlorine)
  • Liquid (bromine)
  • Solid (carbon, sulphur, phosphor)
  • Different colours
  • Opaque or transparent
  • Fragile
  • Don’t conduct electricity and heat (insulators)

Metalloids

  • They have metallic and nonmetallic properties

 

Frequency of Elements

In the Universe:

  • H: 90.8%
  • He: 9.1%

In the Earth:

  • O: 52%
  • Si: 16%
  • Al: 5.5%

 

 

Noble gases

Group VIII: helium, neon, argon, krypton, xenon, radon

Structure:

  • Atoms: closed outer shells
  • Monoatomic elements

Physical properties:

  • Colourless, odourless gases
  • Insoluble in water
  • Don’t conduct electricity (insulators)

Chemical properties:

  • Noble gas notation: closed outer shell
  • Nonreactive substances: don’t form chemical bonds and compounds

Occurence:

  • In the air
  • In rocks
  • In crude oil and natural gas
  • In stars

Use:

  • He: filling airships, balloons
  • He: artificial air (divers)
  • Ne: „neon lights”
  • Ar: protective gas in welding
  • Kr: light bulbs
  • Rn: radioactive (danger of cancer, rock dating)

 

 

Hydrogen

Structure

  • Atom: 1 proton, 1 electron
  • Molecule: H – H, H2 (covalent bonding, nonpolar molecule)

Physical properties

  • Odorless, colourless gas
  • Insoluble in water
  • Density is the smallest (14,5 times lighter than the air)

Chemical properties

Combustion:

  • 2H2 + O2 = 2H2O
  • Mixture of hydrogen and oxygen (2:1): explosive gas

Reaction with chlorine:

  • H2 + Cl2 = 2HCl

Reaction with copper oxide:

  • CuO + H2 = Cu + H2O
  • H2 is reducing agent

Occurrence

  • Volcanic gases
  • Upper atmosphere
  • In compounds

Production

  • Electrolysis of water
  • C + H2O = CO + H2

Use

  • Production of ammonia, ammonium nitrate (fertilizer)
  • Welding

 

 

 

Group VII: Halogens

Name: „salt-makers”

  • Fluorine (F): pale yellow gas
  • Chlorine (Cl): yellow-green gas
  • Bromine (Br): orange-brown liquid
  • Iodine (I): grey crystals

Structure:

  • Outer shell: 7 electrons
  • In nature: diatomic molecules, covalent bonding: F2, Cl2, Br2, I2
  • Nonpolar molecules

 

Chlorine

Physical characteristics:

  • Yellow-green gas
  • Distinctive odour (makes cough)

Chemical characteristics:

  • Diatomic molecules
  • Reactive
  • Poisonous

Reaction with water:

  • Cl2 + H2O = HCl + HOCl
  • Bleach: decolorises

Reaction with hydrogen:

  • H2 + Cl2 = HCl

Reaction with sodium:

  • Na + Cl2 = NaCl  redoxireaction

Occurence: in volcanic gases, in compounds

Importance:

  • Poisonous, disinfectant,
  • Industry: hydrochloric acid, pesticides, pharmaceutical industry

 

 

Iodine

  • Grey, solid crystals, vapour is violet

Solubility:

  • Slightly soluble in water
  • Soluble in oil, gasoline, alcohol

Sublimation: solid transforms to gas without liquid state

Importance: disinfectant

 

Hydrogen chloride

Structure:

  • H-Cl
  • Electronegativity: H: 2.1, Cl: 3.0
  • Cl attracts the bonding electrons much more: polar bond, dipole molecule

Physical properties:

  • Colourless gas
  • Distinctive odor (makes cough)
  • Soluble in water: forms hydrochloric acid
  • Acidic pH:
  • HCl + H2O = H3O+ + Cl-      Hydronium ion and chloride ion is formed

Chemical reactions

Reacts with metals (except copper), hydrogen and salts are formed:

  • 2HCl + Zn = ZnCl2 + H2
  • 6HCl + 2Al = 2AlCl3 + 3H2

Occurence:

  • Volcanic gases
  • Stomach

Production:

  • H2 + Cl2 = 2HCl

Use:

  • Cleaning
  • Textile, paint and pharmaceutical industry

 

Sodium chloride

Structure:

  • NaCl: ionic lattice

Physical properties:

  • Colourless cubic crystals
  • High melting and boiling point
  • Soluble in water, neutral solution

Occurence:

  • Seas and oceans
  • Salt deposits

Importance:

  • Na, Cl2, glass production
  • In living creatures (blood, cytoplasm)
  • Food preservation