Oxygen
Lenka Šibravová, Soňa Konečná
OXYGEN
the element is very common
major component of air
the second largest single component of the earth's atmosphere
(21% by volume)
the atmosphere of Mars contains only about 0.15% oxygen
usually bound with other elements
produced by plants during photosynthesis
necessary for aerobic respiration
plant = rostlina
bound = vázaný
necessary = nutný, nezbytný
photosynthesis = fotosyntéza
Properties
•
•
•
•
Name: Oxygen
Symbol: O
Atomic number: 8
Atomic weight:
15.9994
• Group number: 16
• Group name:
Chalcogen
• Period number: 2
Properties
heavier than air
soluble in water
without smell or taste
the gas is colourless, odourless and tasteless
chemical bonds with almost all other elements
three isotopes
heavy = těžký
soluble = rozpustný
taste = chuť
Property
liquid O2 and solid O2
have a light blue color
highly paramagnetic
electronegativity
highly oxidizing
releasing heat
release = uvolnit
liquid = kapalný
solid = pevný
Liquid oxygen
Properties
the shell structure of
oxygen
crystal structure of
oxygen.
History
• Discovered by: Joseph Priestley, Carl Scheele
• Discovered at: England, Sweden
• Discovered when: 1774
Joseph Priestley
Preparation
• large number of different methods for its preparation
1) Preparation of oxygen using potassium chlorate
2 KClO3 ==> 2 KCl + 3 O2
2) Preparation of oxygen using hydrogen peroxide
2 H2O2 ==> 2 H2O + O2
use = použít
potassium = draslík
Preparation
3) Preparation of oxygen by electrolysis of water
2 H2O ==> 2 H2 + O2
4) Preparation of oxygen by the decomposition of
salts
2 KNO3 ==> 2 KNO2 + O2
5) Preparation of oxygen from air
electrolysis of water = elektrolýza vody
decomposition of salts = rozklad solí
Compounds
• oxygen is very reactive
• oxygen forms chemical bonds with almost all other
•
•
elements
oxygen derivatives are prone to form free radicals
the most common oxidation numbers are -2
chemical bond = chemická vazba
prone = náchylný, nakloněný
free radicals = volné radikály
oxidation numbers = oxidační číslo
Compounds
Hydroxide
Aluminium hydroxide, Al(OH)3
Barium hydroxide, Ba(OH)2
Oxide
Water
Carbon dioxide, CO2
has the chemical formula H2O
Alcohols (R-OH)
methanol, CH3OH
Methanol burns in air forming carbon dioxide and water:
2CH3OH + 3 O2 → 2CO2 + 4H2O
Ozone
 allotropic form of oxygen
 important component of the atmosphere
 effect on the ozone layer
 ozone is toxic!
 used for drinking water treatment
important = důležitý
drinking water = pitná voda
layer = vrstva
treatment = léčba
Applications
 oxygen is essential to respiration
 used in medicine
 used in welding
 making of steel and methanol
essential = nezbytný
steel = ocel
weld = svářet kovy
Thank You