element

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element Substance that cannot be split into simpler substances by chemical means. All atoms of a given element have the same atomic number (at.no.) and thus the same number of protons and electrons. The atoms can have different atomic mass numbers and a natural sample of an element is generally a mixture of isotopes. The known elements range from hydrogen (at.no. 1) to unnilenium (at.no. 109); elements of the first 95 atomic numbers exist in nature, the higher numbers have been synthesized. See also periodic table

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