![]() There is a compound with a positive oxidation state of oxygen (+1), O₂F₂ (oxygen monofluoride, obtained in the reaction of molecular oxygen and fluorine). It is obtained in the combustion of water in an atmosphere of fluorine, and also by the reaction:ĢF₂ + 2NaOH = OF₂ + 2NaF + H₂O (ozone and hydrogen peroxide can also form in the reaction). The compound is called “oxygen fluoride II”. As fluorine is a more electrically negative element than oxygen, it acquires the negative oxidation state (-1) in the compound. Only in one case can oxygen have a positive oxidation state of +2 – in a compound with fluorine, with the formula OF₂. In a free state, oxygen has the oxidation state of 0, like other simple substances. The formation of peroxides is characteristic for hydrogen ( hydrogen peroxide H₂O₂) and some metals (for example, sodium peroxide Na₂O₂, barium peroxide BaO₂, calcium peroxide CaO₂ etc.). In peroxides, the oxidation state of oxygen is -1. For H₃O⁺, the valence of oxygen is equal to three, as oxygen forms three bonds – two covalent and one donor-acceptor. In compounds of this type (apart from the hydroxonium ion), the valence of oxygen (its ability to form a certain number of chemical bonds) is equal to two. Typical examples of compounds where oxygen has an oxidation state of -2 are H₂SO₄, H₂O, KNO₃ and CaO (in the hydroxonium ion H₃O⁺ the oxidation state of oxygen is also -2). electrolysis of salts of acids containing oxygen:ĢCuSO₄ + 2H₂O₂ = 2Cu + 2O₂ + 2H₂SO₄ CuSO₄ hydrate crystalsīeing a strong oxidizer, oxygen most frequently displays an oxidation state of -₂ in compounds (other chalcogens have a lower oxidation state).There are numerous methods for obtaining oxygen:ĭistillation of liquid air (its rectification) Įlectrolysis of water according to the following equation:ĢH₂O = O₂ + 2H₂ (presence of an alkali is necessary) Ozone is a very reactive substance, and surpasses molecular oxygen by its reactivity and oxidation properties.Ĭlick here for experiments with pure oxyden. ![]() To prevent this from happening, it must be cooled to -78 ᵒC or -108.4 ᵒF in a hermetic glass or metal container, or have a little nitric acid added to it. The O₃ molecule is rather unstable, so for a relatively short time (several tens of minutes), it breaks down into molecular oxygen. ![]() It forms from the breakdown of molecular oxygen into atomic oxygen (this takes place with an electrical charge, harsh ultraviolet irradiation of the air or the breakdown of peroxides). In a solid state, the substance forms dark blue, almost black crystals. If it is compressed, it acquires a rich blue color. Ozone is a poisonous gas of a bluish color with a specific smell. Molecular oxygen has the allotropic modification O₃ (ozone). In nature, the maximum quantity of oxygen is contained in the air (around 21% of its volume), in water and in the earth’s crust (up to 47% oxygen by mass). Oxygen can be encountered most frequently with the atomic numbers 16, 17 or 18. In nature it is in encountered in the form of three isotopes (elements with an identical number on the periodic table, but with different atomic numbers). In an atmosphere of oxygen, breathing and decomposition are also possible. It has no taste or smell, but its presence can be identified with a smoldering stick: when it is placed in an atmosphere of oxygen it flares up, as oxygen supports combustion well. Oxygen is a colorless diatomic gas in normal conditions. ![]() In translation, “chalcogen” means “giving birth to ore” Physical properties of oxygen, its presence in nature It is a member of the group of chalcogens (besides oxygen, they include sulfur, selenium, tellurium and polonium). \): Color chart for thermally grown SiO 2 films observed under daylight fluorescent lighting.Oxygen is an element of the 6ᵗʰ group (according to the new classification an element of the 16th group) of the main subgroup of the periodic table. ![]()
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