selenium
- History. In 1817 Swedish chemist Jöns Jacob Berzelius noted a red substance resulting from sulfide ores from mines of Falun, Sweden.
- Occurrence and uses. The proportion of selenium in Earth’s crust is about 10 −5 to 10 −6 percent. ...
- Allotropy. ...
- Preparation. ...
- Physical-electrical properties. ...
- Compounds. ...
Where is selenium commonly found on Earth?
selenium
- History. In 1817 Swedish chemist Jöns Jacob Berzelius noted a red substance resulting from sulfide ores from mines of Falun, Sweden.
- Occurrence and uses. The proportion of selenium in Earth’s crust is about 10 −5 to 10 −6 percent. ...
- Allotropy. ...
- Preparation. ...
- Physical-electrical properties. ...
- Compounds. ...
Where is selenium found in the world?
Selenium is also found in various types of meat, including beef and pork. Levels are most significant in animals raised in regions with selenium-rich soil. The high plains regions of Nebraska and the Dakotas, for example, have some of the highest concentrations of selenium in the country.
How can I locate this element with Selenium WebDriver?
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Is selenium on the periodic table?
Selenium, symbol Se, can be found in group sixteen on the periodic table, to the right of arsenic, and to the left of bromine. As a chalcogen, it shares similar properties to tellurium below it, and sulfur above it. The selenium atom has an electron configuration of [Ar] 3d10 4s2 4p4
Who was the element selenium discovered by?
Jöns Jacob BerzeliusJohan Gottlieb GahnSelenium/Discoverers
Where is selenium found in nature?
Because selenium occurs naturally in Earth's crust, its presence in air, water, and soil results from both geologic reactions and human activity. Selenium is found concentrated naturally in soils that overlie bedrock with high selenium concentrations.
When was selenium first discovered?
1817Selenium / Discovered
What is selenium found in or used for?
Uses of Selenium Selenium is used in the glass industry to decolorize glass and to make red-colored glasses and enamels. It is used as a catalyst in many chemical reactions. Selenium is used in solar cells and photocells – in fact the first solar cell was made using selenium. It is also used as a photographic toner.
How is selenium extracted from the earth?
Selenium is mostly extracted from the anode mud formed during the electrolytic refining of copper. Plants take up selenium from the soil and propagate it through the food chain. Selenium is found in water supplies as selenate and selenite.
How do we mine selenium?
The main source of selenium in mining operations is waste rock. Selenium species leach or migrate to the environment from the rock when it is exposed to water. More frequently, selenium occurs in the soluble form in mine runoffs.
Who and when was selenium discovered?
Jöns Jacob BerzeliusJohan Gottlieb GahnSelenium/Discoverers
Why selenium is called selenium?
The name Selenium comes from a joke made by Huggins in an email, mocking a competitor named Mercury, saying that you can cure mercury poisoning by taking selenium supplements. The others that received the email took the name and ran with it.
What is an interesting fact about selenium?
Here are some interesting facts about selenium: Selenium gets its name from the Greek word "selene," which means "moon." Selene was the Greek goddess of the moon. Selenium has atomic number 34, meaning each atom has 34 protons. The element symbol of selenium is Se.
Is selenium naturally occurring?
Selenium is a trace mineral, which means that the body only needs a small amount of it. It is found naturally in foods or as a supplement.
What's the nature of selenium?
semi-metallic elementSelenium is a semi-metallic element that belongs to the family of chalcogens (group 15). Placed just between sulfur and tellurium in that column of the periodic table, it resembles both elements in some aspects.
Why is selenium bad for the environment?
It is strongly bioaccumulated by aquatic organisms and even slight increases in waterborne concentrations can quickly result in toxic effects such as deformed embryos and reproductive failure in wildlife.
Is selenium toxic to humans?
Selenium toxicity can occur with acute or chronic ingestion of excess selenium. Symptoms of selenium toxicity include nausea; vomiting; nail discoloration, brittleness, and loss; hair loss; fatigue; irritability; and foul breath odor (often described as “garlic breath”).
Why is selenium low in HIV?
Selenium levels are often low in people living with HIV, possibly because of inadequate intakes (especially in developing countries), excessive losses due to diarrhea, and malabsorption [ 2, 25 ]. Observational studies have found an association between lower selenium concentrations in people with HIV and an increased risk of cardiomyopathy, death, and, in pregnant women, HIV transmission to offspring and early death of offspring [ 26-30 ]. Some randomized clinical trials of selenium supplementation in adults with HIV have found that selenium supplementation can reduce the risk of hospitalization and prevent increases of HIV-1 viral load; preventing HIV-1 viral load progression can lead to increases in numbers of CD4 cells, a type of white blood cell that fights infection [ 31, 32 ]. However, one trial showed that selenium supplementation in pregnant women can prevent early death in infants but has no effects on maternal viral load or CD4 counts [ 33, 34 ].
What foods contain selenium?
Includes a variety of protein foods such as lean meats; poultry; eggs; seafood; beans, peas, and lentils; nuts and seeds; and soy products. Pork, beef, turkey, chicken, fish, shellfish, and eggs contain high amounts of selenium . Some beans and nuts, especially Brazil nuts, contain selenium.
What are the factors that affect the amount of selenium in plant based food?
The amount of selenium in a given type of plant-based food depends on the amount of selenium in the soil and several other factors, such as soil pH, amount of organic matter in the soil, and whether the selenium is in a form that is amenable to plant uptake [ 2, 6, 8, 9 ].
What is the RDA for nutrition?
These values, which vary by age and sex, include: Recommended Dietary Allowance (RDA): Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.
What are the most commonly used measures of selenium?
The most commonly used measures of selenium status are plasma and serum selenium concentrations [ 1 ]. Concentrations in blood and urine reflect recent selenium intake. Analyses of hair or nail selenium content can be used to monitor longer-term intakes over months or years.
What is the role of selenium in the body?
Selenium, which is nutritionally essential for humans, is a constituent of more than two dozen selenoproteins that play critical roles in reproduction, thyroid hormone metabolism, DNA synthesis, and protection from oxidative damage and infection [ 1 ].
What are the guidelines for healthy eating?
The Dietary Guidelines for Americans describes a healthy dietary pattern as one that: 1 Includes a variety of vegetables; fruits; grains (at least half whole grains); fat-free and low-fat milk, yogurt, and cheese; and oils.#N#Many whole grains and dairy products, including milk and yogurt, are good sources of selenium. Some ready-to-eat breakfast cereals are fortified with selenium, and some fruits and vegetables contain selenium. 2 Includes a variety of protein foods such as lean meats; poultry; eggs; seafood; beans, peas, and lentils; nuts and seeds; and soy products.#N#Pork, beef, turkey, chicken, fish, shellfish, and eggs contain high amounts of selenium. Some beans and nuts, especially Brazil nuts, contain selenium. 3 Limits foods and beverages higher in added sugars, saturated fat, and sodium. 4 Limits alcoholic beverages. 5 Stays within your daily calorie needs.
