atom

(at′ŏm)

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[Gr. atomos, indivisible]
The smallest part of an element. An atom consists of a nucleus and surrounding electrons. The nucleus is positively charged, and this determines the atomic number of an element. A large number of entities in the atomic nucleus have been identified, and the search for others continues. Dimensions of atoms are of the order of 10−8 cm.
SEE: atomic theory; SEE: electron
atomic (ă-tom′ik)
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, adj.

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