Oxygen is a colourless, odourless reactive gas, the chemical element of atomic number 8 and the life-supporting component of the air. It is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds.
Common uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.
One hundred million tonnes of oxygen are extracted from air for industrial uses annually by two primary methods. The most common method is fractional distillation of liquefied air, with nitrogen distilling as a vapor while oxygen is left as a liquid. The other primary method of producing oxygen is passing a stream of clean, dry air through one bed of a pair of identical zeolite molecular sieves, which absorbs the nitrogen and delivers a gas stream that is 90% to 93% oxygen.
Protons and Neutrons in Oxygen
Oxygen is a chemical element with atomic number 8 which means there are 8 protons in its nucleus. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs.
The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. Neutron number plus atomic number equals atomic mass number: N+Z=A. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.
For stable elements, there is usually a variety of stable isotopes. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. Mass numbers of typical isotopes of Oxygen are 16; 17; 18.
Main Isotopes of Oxygen
Naturally occurring oxygen is composed of three stable isotopes, 16O, 17O, and 18O, with 16O being the most abundant (99.762% natural abundance).
Oxygen-16 is composed of 8 protons, 8 neutrons, and 8 electrons. Most 16O is synthesized at the end of the helium fusion process in stars; the triple-alpha reaction creates 12C, which captures an additional 4He to make 16O. The relative and absolute abundance of 16O is high because it is a principal product of stellar evolution.
Oxygen-17 is composed of 8 protons, 9 neutrons, and 8 electrons. Both 17O and 18O are secondary isotopes, meaning that their nucleosynthesis requires seed nuclei.
Oxygen-18 is composed of 8 protons, 10 neutrons, and 8 electrons.
Oxygen-15, which is an unstable isotope of oxygen, is composed of 8 protons, 7 neutrons, and 8 electrons. It is frequently used in positron emission tomography, or PET imaging. Oxygen-15 is synthesized through deuteron bombardment of nitrogen-14 using a cyclotron.
Electrons and Electron Configuration
The number of electrons in an electrically-neutral atom is the same as the number of protons in the nucleus. Therefore, the number of electrons in neutral atom of Oxygen is 8. Each electron is influenced by the electric fields produced by the positive nuclear charge and the other (Z – 1) negative electrons in the atom.
Since the number of electrons and their arrangement are responsible for the chemical behavior of atoms, the atomic number identifies the various chemical elements. The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. In the periodic table, the elements are listed in order of increasing atomic number Z.
Electron configuration of Oxygen is [He] 2s2 2p4.
Possible oxidation states are -2.
Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. It is a strong oxidizing agent with high electronegativity and forms O2 at Standard Temperature and Pressure (STP). Metal oxides typically contain an anion of oxygen in the oxidation state of −2. Most of the Earth’s crust consists of solid oxides, the result of elements being oxidized by the oxygen in air or water. ven materials considered pure elements often develop an oxide coating. For example, aluminum foil develops a thin skin of Al2O3 (called a passivation layer) that protects the foil from further corrosion. Due to its electronegativity, oxygen forms stable chemical bonds with almost all elements to give the corresponding oxides.
Most Common Chemical Compound of Oxygen
Water is the most common chemical compound of hydrogen and oxygen. Its chemical formula is H2O, meaning that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds.Two hydrogen atoms attached one oxygen atom at angle of 104.45°.
|Number of protons||8|
|Number of neutrons (typical isotopes)||16; 17; 18|
|Number of electrons||8|
|Electron configuration||[He] 2s2 2p4|
Properties of other elements