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Aluminium (or aluminum in North American English) is a chemical element; it has symbol Al and atomic number 13. Aluminium has a density lower than that of other common metals, about one-third that of steel. It has a great affinity towards oxygen, forming a protective layer of oxide on the surface when exposed to air.
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Periodic table of the chemical elements showing the most or more commonly named sets of elements (in periodic tables), and a traditional dividing line between metals and nonmetals. The f-block actually fits between groups 2 and 3 ; it is usually shown at the foot of the table to save horizontal space.
Like the periodic table, the list below organizes the elements by the number of protons in their atoms; it can also be organized by other properties, such as atomic weight, density, and electronegativity. For more detailed information about the origins of element names, see List of chemical element name etymologies.
A silvery-colored metal, tin is soft enough to be cut with little force, [13] and a bar of tin can be bent by hand with little effort. When bent, the so-called "tin cry" can be heard as a result of twinning in tin crystals. [14] Tin is a post-transition metal in group 14 of the periodic table of elements.
In 1923, Horace G. Deming, an American chemist, published short (Mendeleev style) and medium form periodic tables. [17] Each one had a regular stepped line separating metals from nonmetals. Merck and Company prepared a handout form of Deming's 18-column table, in 1928, which was widely circulated in American schools.
The seven metals known since Classical times in Europe were associated with the seven classical planets; this figured heavily in alchemical symbolism. The exact correlation varied over time, and in early centuries bronze or electrum were sometimes found instead of mercury, or copper for Mars instead of iron; however, gold, silver, and lead had ...
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 ...