Search results
Results From The WOW.Com Content Network
The most reactive metals, such as sodium, will react with cold water to produce hydrogen and the metal hydroxide: . 2 Na (s) + 2 H 2 O (l) →2 NaOH (aq) + H 2 (g). Metals in the middle of the reactivity series, such as iron, will react with acids such as sulfuric acid (but not water at normal temperatures) to give hydrogen and a metal salt, such as iron(II) sulfate:
From left to right in the periodic table, the nonmetals can be divided into the reactive nonmetals and the noble gases. The reactive nonmetals near the metalloids show some incipient metallic character, such as the metallic appearance of graphite, black phosphorus, selenium and iodine. The noble gases are almost completely inert.
Selenium is produced by roasting the coinage metal selenides X 2 Se (X = Cu, Ag, Au) with soda ash to give the selenite: X 2 Se + O 2 + Na 2 CO 3 → Na 2 SeO 3 + 2 X + CO 2; the selenide is neutralized by sulfuric acid H 2 SO 4 to give selenous acid H 2 SeO 3; this is reduced by bubbling with SO 2 to yield elemental selenium. Polonium and ...
[n 6] Selenium, in particular, is commonly designated as a metalloid in environmental chemistry [n 7] on account of similarities in its aquatic chemistry with that of arsenic and antimony. [n 8] There are fewer references to beryllium, in spite of its periodic table position adjoining the dividing line between metals and nonmetals. Isolated ...
The chemistry of selenium is largely covalent in nature, noting it can form ionic selenides with highly electropositive metals. The common oxide of selenium (SeO 3) is strongly acidic. Tellurium. Tellurium is a silvery-white, moderately reactive, [8] shiny solid, that has a density of 6.24 g/cm 3 and is soft (MH 2.25) and brittle. It is the ...
A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics.
[29] [dubious – discuss] Nonmetals closer to the left or bottom of the periodic table (and so closer to the metals) often have metallic interactions between their molecules, chains, or layers; this occurs in boron, [30] carbon, [31] phosphorus, [32] arsenic, [33] selenium, [34] antimony, [35] tellurium [36] and iodine.
Selenium (Se) is an element in group 16, the chalcogens. Selenium is the first nonmetal in period 4, with properties similar to sulfur. Selenium is quite rare in pure form in nature, mostly being found in minerals such as pyrite, and even then it is quite rare. Selenium is necessary for humans in trace amounts, but is toxic in larger quantities.