Nitrogen Dioxide NO2
Made from nitrogen and oxygen
Chemical bonding
Convalent bonding
Harmful effects
Nitrogen dioxide is harmful to vegetation, can fade and discolour fabrics, reduce visibility, and react with surfaces and furnishings. Vegetation exposure to high levels of nitrogen dioxide can be identified by damage to foliage, decreased growth or reduced crop yield. Indoor domestic appliances (gas stoves, gas or wood heaters) can also be significant sources of nitrogen oxides, particularly in areas that are poorly ventilated. Nitric oxide does not significantly affect human health. On the other hand, elevated levels of nitrogen dioxide cause damage to the mechanisms that protect the human respiratory tract and can increase a person's susceptibility to, and the severity of, respiratory infections and asthma. Long-term exposure to high levels of nitrogen dioxide can cause chronic lung disease. It may also affect sensory perception, for example, by reducing a person's ability to smell an odour.
Constituent elements
Nitrogen
a chemical element that has the symbol N, atomic number of 7 and atomic mass of 14.00674 u. Elemental nitrogen is a colourless, odourless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere.
Oxygen
Oxygen is a colourless, odourless, tasteless gaseous chemical element which appears in great abundance on Earth, trapped by the atmosphere. Many people are familiar with oxygen, because it is a vital component of the respiration process; without oxygen, most organisms will die within minutes. A number of forms of oxygen and oxygen compounds can be found in nature. Oxygen can also be isolated and sold in pure form for an assortment of uses, and was first isolated and identified in 1774. The atomic number of oxygen is eight, and it is identified by an O symbol on the periodic table of elements. In addition to being very widely distributed on Earth, oxygen is also the third most abundant element in the universe, and it is a key catalyst in many chemical reactions. Oxidation is one such reaction, and it occurs when oxygen mixes with other elements and compounds. Oxygen also plays a role in combustion.
NOx (often written NOx) refers to NO and NO2. They are produced during combustion, especially at high temperature. These two chemicals are important trace species in Earth's atmosphere. In the troposphere, during daylight, NO reacts with partly oxidized organic species (or the peroxy radical) to form NO2, which is then photolyzed by sunlight to reform NO: NO + CH3O2 → NO2 + CH3O, NO2 + sunlight → NO + O. The oxygen atom formed in the second reaction then goes on to form ozone; this series of reactions is the main source of tropospheric ozone. CH3O2 is just one example of many partly oxidized organic molecules that can react with NO to form NO2.
Dot diagram
Acknowledgements
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