What is iodine? The molar mass of this element is 127 g / mol. Consider the main characteristics of this halogen, its significance for living organisms.
Introduction
To begin with, halogen was discovered at the beginning of the nineteenth century by the French chemist Courtois. Where is iodine located in the periodic system ? The molar mass of this element was indicated above, and its serial number is 53. It refers to halogens, is in the VIIA subgroup. Under natural conditions, it exists in the form of a stable atom, in addition, the radioactive isotopes of iodine were synthesized.
Atom structure
Iodine, whose molar mass is 127 g / mol, at the external energy level contains seven valence electrons. In addition, he has a vacant d-orbital. In a variety of compounds, it exhibits odd oxidation states. A significant molar mass of iodine, a large atomic radius, and an insignificant ionization energy allow such an element not only to exhibit acceptor properties, but also become an electron donor in some chemical interactions.
Physical properties
Since the molar mass of iodine 2 is 254 g / mol, more precisely, its molecules, this substance at room temperature is a violet-black crystalline substance with a metallic luster. Its crystals are diatomic molecules formed due to the inter-molecular interaction of Van der Waals.
Iodine, the molar mass of the molecule of which is 254 g / mol, is sublimated when heated to 183 ° C, forming violet-colored vapors. This substance is poorly soluble in water. With increasing temperature, this indicator increases. Iodine, the molar mass of which is considered to be quite large, forms a complex compound in the iodide solution. Its atom has a rapidly polarizable electron shell. Cations of many elements are able to get into the electron shell of an atom, leading to its deformation. That is why the existence of a positively polarized iodine atom is allowed, color appears, and the physiological activity of iodine compounds is high.
Chemical properties
The molar mass of iodine explains its low chemical activity. It does not interact with most metals, inert gases, carbon, nitrogen. With metals, it forms iodides with an ionic bond.
Saturated organic substances do not interact with iodine, since the C – H bond energy exceeds the figure between carbon and iodine.
Biological significance
What is iodine needed for the human body? Molar mass and chemical properties are discussed above, now we will focus on its physiological characteristics. It refers to the most important trace elements that take part in metabolic processes. In the body of an adult is about 30 mg of iodine, with about 10 mg located in the thyroid gland. In the body, this element is in the form of iodides, organic compounds (Tireglobulin protein), iodinated amino acids.
The molar mass of the equivalent of iodine is 127; it is used in quantitative calculations.
Functional meaning
The main source of this element for humans is plant food. From the intestines, this halogen enters the bloodstream, then is captured by the thyroid gland. The kidneys are responsible for removing iodine from the body.
In the thyroid gland there are special enzymatic systems that carry out the conversion of iodine from an inactive biological form to an active state.
Transformation Features
On the outer surface of the cell membrane, its iodide oxidase oxidizes to hypoiodite; it is he who gets into the body through the cell membrane.
Inside the cell, it is restored due to the action of the enzyme iodine reductase to iodide. It is he who is an active participant in the process of biosynthesis of thyroid hormones.
Hypothesis of the synthesis of thyroxine and triiodothyronine
Currently, there are two main versions about this transformation. According to one hypothesis, iodine is attached to the thyroglobulin molecule under the action of the enzyme (the molar mass and properties are indicated earlier).
Further, the resulting molecule decomposes with the formation of thyroxine, as well as other iodine-containing products.
The second version is that there is tyrosine iodination, then the synthesis of thyreglobulin. The possibility of the existence of stepwise thyroxine biosynthesis is allowed. At the first stage, the tyrosine molecule is iodized, diiodotyrosine is formed. At the second stage, their enzymatic condensation occurs with the release of alanine.
Circulating blood contains about 70 percent of iodine in organic compounds, the rest are in the form of an iodide ion.
For a healthy person, a low concentration of thyroid free hormones in the blood plasma is assumed. Most of the iodine-containing organic substances are represented by thyroxine, which is associated with specific plasma proteins: albumin, globulin.
Thyroid hormones that enter the tissues from blood plasma will be released from the plasma proteins from the bond, they play a hormonal role.
Interesting Facts
More than half of the densely populated territory of our state suffers from insufficient iodine content in soil, water, and food products. Therefore, the problem of iodine deficiency for Russia is currently particularly relevant. Iodine, molar mass and its characteristics - a question that is considered in the school chemistry course.
At first, a small increase in the thyroid gland occurs, but then the disease passes to the rest of the body's system. As a result, metabolic processes are disturbed, growth is slowed down. In some cases, endemic goiter causes deafness, cretinism. There is lethargy, weakness, fatigue, poor mood, and appetite decreases. In children and adolescents, school performance is significantly reduced, interest in cognitive activity is lost, and excessive aggression appears.
Danger of oversupply
Pure iodine is a potent poison. Vomiting begins with brown contents. Body temperature rises. A drop in blood pressure is noted, convulsions may occur. It is necessary for the victim to rinse the stomach, give a large amount of starch, flour paste, saline laxative. Take the victim to the hospital.
Drinking alcohol tincture can cause burns to the mucous membranes of the oral cavity, pharynx, larynx, esophagus, and stomach. In the presence of allergies, any self-treatment with iodine-containing drugs is excluded!
When treating wounds and scratches with iodine, only the edges of the wound are lubricated - blood reduces the bactericidal properties of iodine, and when iodine gets on tissues that are not protected by the skin, it causes severe burns.
In what form does this element enter our body? The source may be salt, in which 167 g / mol is the molar mass. Potassium iodine is a salt that is found in many marine products when dissolved. That is why doctors recommend eating algae, marine fish to make up for the lack of iodine in the body.
Conclusion
The total amount in the human body contains from twenty to thirty-five milligrams of iodine. Its distribution throughout the body is very uneven: a smaller part of iodine is concentrated in the blood and kidneys, and a large part in the thyroid gland.
If we talk about the absolute values of the quantitative content of iodine in a living organism, then it should be noted that about half of all iodine is located in the thyroid gland (about 10-15 mg). It is she who is called the organ in which iodine accumulates. A significant amount of this element was found in the following products: in the liver, hair, prostate gland, pituitary gland, and bile. In muscles, the approximate concentration of halogen is a thousand times less than in the thyroid gland.
In our body, iodine comes to a greater extent through the digestive tract. Many inorganic iodine compounds are found in foods and water. They can be absorbed along almost the entire length of the gastrointestinal tract, but the process occurs more intensively in the small intestine. Also, iodine enters the body through the lungs, which is obvious for coastal marine areas. In 4000 liters of air passing through the lungs of a person in 12 hours, contains 0.044 mg of iodine, a fifth of which is exhaled back. Small amounts of iodine pass through the skin.
An excess of iodine in the human body is much less common than its lack. Basically, from an excess of iodine, problems arise in people who are engaged in production related to the extraction of iodine salts.
Doctors do not recommend the abuse of iodine, they call a safe dose of 500 mg of iodine. Excess of this halogen leads to toxicity (poisoning) of the body.
Despite the fact that in the subgroup of halogens there are several chemical elements, iodine is of the greatest biological importance. Deficiency of this element in the human body leads to serious health problems, so it is so important to undergo an examination of the thyroid gland in a timely manner.
Doctors are worried that recently there has been an increase in patients among children and adolescents.