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Radium is a chemical element; it has symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather than oxygen) upon exposure to air, forming a black surface layer of radium nitride (Ra 3 N 2).
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.
English: This pictorial periodic table is colorful, boring, and packed with information. In addition to the element's name, symbol, and atomic number, each element box has a drawing of one of the element's main human uses or natural occurrences. The table is color-coded to show the chemical groupings.
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 few other images are of low quality but it might be hard to find versions of higher quality: Ba (oxidises too easily), Pm, Ra, Pa (radioactives). A few images are only available as fair-use: Po, Np, Cm. It may be possible to find a free alternative (although it would be quite difficult).
Atomic radii vary in a predictable and explicable manner across the periodic table. For instance, the radii generally decrease rightward along each period (row) of the table, from the alkali metals to the noble gases; and increase down each group (column). The radius increases sharply between the noble gas at the end of each period and the ...
The synthetic elements are those with atomic numbers 95–118, as shown in purple on the accompanying periodic table: [1] these 24 elements were first created between 1944 and 2010. The mechanism for the creation of a synthetic element is to force additional protons into the nucleus of an element with an atomic number lower than 95.
Tl is located on the periodic table near two other highly toxic metals, mercury and lead. Tin poisoning from tin metal, its oxides, and its salts are "almost unknown"; on the other hand certain organotin compounds are almost as toxic as cyanide. Such organotin compounds were once widely used as anti-fouling agents. [33]