Page 45 - Curriculum Visions Dynamic Book

Oxygen (O)
Element 8. Oxygen is a non-metallic chemical element in group 6 (the oxygen group) in the Periodic Table.
Oxygen is the most common gas
after nitrogen, making up just over one-
fifth of the Earth’s atmosphere. It is the
third most abundant element in the
universe after hydrogen and helium. It
is a colourless, tasteless and odourless
gas.When electrically excited, it
produces colours.They are, for example,
responsible for the bright red and yellow–green colours of an aurora in the night sky (northern or southern lights).
Oxygen is very reactive and reacts with many elements to produce oxides.The most common oxide is water.
Ozone (O3) is a form of oxygen created when electrical discharges or ultra-violet light act on oxygen, O2. Ozone is harmful if breathed in too large concentrations. High in the atmosphere, however, ozone prevents harmful ultra- violet rays from the Sun from reaching the Earth
in too high a concentration. Ozone can be
destroyed by reacting it with some gases.
Oxygen is essential for combustion, and spacecraft therefore have to
take their own supply of liquid oxygen as well as fuel.
Oxygen is produced
by liquefying air. Liquid
oxygen is magnetic. High concentrations of oxygen present a fire hazard because of the increased risk of spontaneous combustion.
Key facts...
Name: oxygen
Symbol: O
Atomic number: 8
Atomic weight: 16
Position in Periodic Table: group 6 (16)
(oxygen group; chalcogen); period 2
State at room temperature: gas
Colour: colourless as a gas, but pale blue as a liquid Density of gas at 20°C: 1.33 g/l
Melting point: –218.3°C
Boiling point: –182.9°C
Origin of name: the French chemist Antoine
Lavoisier gave oxygen its name, using the Greek words oxy and genes, meaning acid forming.
Shell pattern of electrons: 2–6
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