 Metallic tellurium, diameter 3.5 cm.
Image: anonymous ( license.)
This week's element is tellurium, which has the symbol Te and the atomic number, 52. Its name comes from the Latin, tellus,Whirling Darvish gets better of Verlander as Rangers maul Tigers Sport guardi, for "earth". Despite its name, this lustrous, pale grey metalloid is quite rare on earth, rarer than it is elsewhere in the universe, in fact. The reason for its comparative rarity is attributed to the formation of 2Te, a volatile gas that was lost to space during the early formation of earth.
Tellurium is used in a number of industrial and commercial applications. It is alloyed with stainless steel and copper to improve their machinability and tellurium is used as a semiconductor, telluride is used in solar panels because it has the highest efficiency for electricity generation, tellurium speeds the curing of rubber and renders it less susceptible to aging and to the softening effects of oil, and tellurium , Te,Mulberry outlet, is used in some rewritable CDs and DVDs.
When I was a microbiologist,ghd, one of the many types of growth media that I used to diagnose human pathogens was an agar made with serum and tellurite (2Te3). This agar is used specifically to diagnose the human respiratory pathogen, Corynebacterium diphtheriae. Tellurite agar is a selective medium because tellurium inhibits growth of a variety of bacteria, and it is a differential medium because Corynebacterium will reduce tellurite to metallic tellurium, producing characteristic black or brownish-black colonies on the otherwise pale straw-coloured and transparent agar.
In humans and other animals, tellurium has no known biological role,Mulberry uk, but the body does metabolise it to create the volatile gaseous compound, dimethyl telluride, (3)2Te, which is excreted in sweat and exhaled, and is the source of a charmingly potent "garlic breath", similar to what happens with ingestion. (Which makes me wonder why don't any of these elements make people smell minty or fruity? Why must we always smell like a litter box,ghd sale?) I should point out that taking vitamin C can reduce these odoriferous effects.
Tellurium can be toxic if ingested in high enough quantities,ray ban aviators. *
Chemically speaking, the discovery of tellurium caused the inventor of the of elements, Dmitri Mendeleev, a lot of headaches. This is because tellurium has an atomic mass of 127.6 whilst the element that comes after it, iodine, is lighter with an atomic weight of 126.9. Mendeleev concluded that the atomic mass for one of these two elements must be wrong because tellurium clearly preceded iodine in the periodic table. After 50 years of headbanging frustration and effort by a number of chemists to accurately determine the atomic mass of these two elements, the concept of chemical isotopes was discovered. Isotopes are variant forms of an element that maintain the element's characteristic number of protons, but contain variable numbers of neutrons. As it turns out, the most common isotopes of tellurium have atomic masses of 128 and 130, whilst iodine's most common isotope has an atomic mass of 127. Thus, tellurium has an average atomic mass of 127.6 whilst iodine has an average atomic mass of 126.9.
Here's our favourite professor telling us more about tellurium:
Visit 's YouTube channel [].
* [added 1430 on 2 March 2012] Tellurium is "[h]ighly toxic, may be fatal if inhaled, swallowed or absorbed through skin. Avoid any skin contact. Effects of contact or inhalation may be delayed." []. Sodium tellurite is also toxic: "The material is both an oral and dermal toxic hazard. The material is toxic by ingestion. Oral ingestion of tellurium compounds is generally regarded as extremely toxic. The probable oral lethal dose is 5-50 mg/kg or between 7 drops and 1 teaspoonful for a 70 kg (150 pound) person. Tellurium compounds are regarded as super toxic for skin exposures." [].
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Video journalist is the man with the camera and the is the place with the chemists. You can follow Brady on twitter @ and the University of Nottingham on twitter @
You've already met these elements:
: Sb, atomic number 51
: Sn, atomic number 50
: In, atomic number 49
: Cd, atomic number 48
: Ag, atomic number 47
: Pd, atomic number 46
: Rh, atomic number 45
: Ru, atomic number 44
: Tc, atomic number 43
: Mo, atomic number 42
: Ni, atomic number 41
: Zr, atomic number 40
: Y, atomic number 39
: Sr, atomic number 38
: Rr, atomic number 37
: Kr, atomic number 36
: Br, atomic number 35
: Se, atomic number 34
: As, atomic number 33
: Ge, atomic number 32
: Ga, atomic number 31
: Zn, atomic number 30
: Cu, atomic number 29
: Ni, atomic number 28
: Co, atomic number 27
: Fe, atomic number 26
: Mn, atomic number 25
: Cr, atomic number 24
: V, atomic number 23
: Ti,cheap ghd, atomic number 22
: Sc, atomic number 21
: Ca, atomic number 20
: K, atomic number 19
: Ar, atomic number 18
: Cl, atomic number 17
: S,Mulberry uk, atomic number 16
: P, atomic number 15
: Si, atomic number 14
: Al, atomic number 13
: Mg,ray ban sale, atomic number 12
: Na, atomic number 11
: Ne, atomic number 10
: F, atomic number 9
: O, atomic number 8
: N, atomic number 7
: C, atomic number 6
: B, atomic number 5
: Be, atomic number 4
: Li,Mulberry uk, atomic number 3
: He, atomic number 2
: H, atomic number 1
Here's a wonderful interactive that is just really really fun to play with!
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