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Answers
Answer:
Allotropes of oxygen. For other uses, see Oxygen (disambiguation) and O2 (disambiguation).
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. After hydrogen and helium, oxygen is the third-most abundant element in the universe by mass. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O
2. Diatomic oxygen gas constitutes 20.95% of the Earth's atmosphere. Oxygen makes up almost half of the Earth's crust in the form of oxides.[2]
Oxygen, 8O
A transparent beaker containing a light blue fluid with gas bubbles
Liquid oxygen boiling
Oxygen
Allotropes
O2, O3 (ozone)
Appearance
gas: colorless
liquid and solid: pale blue
Standard atomic weight Ar, std(O)
[15.99903, 15.99977] conventional: 15.999
Oxygen in the periodic table
Hydrogen
Helium
Lithium
Beryllium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon
Sodium
Magnesium
Aluminium
Silicon
Phosphorus
Sulfur
Chlorine
Argon
Potassium
Calcium
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Gallium
Germanium
Arsenic
Selenium
Bromine
Krypton
Rubidium
Strontium
Yttrium
Zirconium
Niobium
Molybdenum
Technetium
Ruthenium
Rhodium
Palladium
Silver
Cadmium
Indium
Tin
Antimony
Tellurium
Iodine
Xenon
Caesium
Barium
Lanthanum
Cerium
Praseodymium
Neodymium
Promethium
Samarium
Europium
Gadolinium
Terbium
Dysprosium
Holmium
Erbium
Thulium
Ytterbium
Lutetium
Hafnium
Tantalum
Tungsten
Rhenium
Osmium
Iridium
Platinum
Gold
Mercury (element)
Thallium
Lead
Bismuth
Polonium
Astatine
Radon
Francium
Radium
Actinium
Thorium
Protactinium
Uranium
Neptunium
Plutonium
Americium
Curium
Berkelium
Californium
Einsteinium
Fermium
Mendelevium
Nobelium
Lawrencium
Rutherfordium
Dubnium
Seaborgium
Bohrium
Hassium
Meitnerium
Darmstadtium
Roentgenium
Copernicium
Nihonium
Flerovium
Moscovium
Livermorium
Tennessine
Oganesson
–
↑
O
↓
S
nitrogen ← oxygen → fluorine
Atomic number (Z)
8
Group
group 16 (chalcogens)
Period
period 2
Block
p-block
Element category
Reactive nonmetal
Electron configuration
[He] 2s2 2p4
Electrons per shell
2, 6
Physical properties
Phase at STP
gas
Melting point
(O2) 54.36 K (−218.79 °C, −361.82 °F)
Boiling point
(O2) 90.188 K (−182.962 °C, −297.332 °F)
Density (at STP)
1.429 g/L
when liquid (at b.p.)
1.141 g/cm3
Triple point
54.361 K, 0.1463 kPa
Critical point
154.581 K, 5.043 MPa
Heat of fusion
(O2) 0.444 kJ/mol
Heat of vaporization
(O2) 6.82 kJ/mol
Molar heat capacity
(O2) 29.378 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 61 73 90
Atomic properties
Oxidation states
−2, −1, 0, +1, +2
Electronegativity
Pauling scale: 3.44
Ionization energies
1st: 1313.9 kJ/mol
2nd: 3388.3 kJ/mol
3rd: 5300.5 kJ/mol
(more)
Covalent radius
66±2 pm
Van der Waals radius
152 pm
Color lines in a spectral range
Spectral lines of oxygen
Other properties
Natural occurrence
primordial
Crystal structure
cubicCubic crystal structure for oxygen
Speed of sound
330 m/s (gas, at 27 °C)
Thermal conductivity
26.58×10−3 W/(m·K)
Magnetic ordering
paramagnetic
Magnetic susceptibility
+3449.0·10−6 cm3/mol (293 K)[1]
CAS Number
7782-44-7
History
Discovery
Carl Wilhelm Scheele (1771)
Named by
Antoine Lavoisier (1777)
Main isotopes of oxygen
Isotope Abundance Half-life (t1/2) Decay mode Product
16O 99.76% stable
17O 0.04% stable
18O 0.20% stable
Category Category: Oxygen
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Dioxygen provides the energy released in combustion[3] and aerobic cellular respiration,[4] and many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone.