Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons (except in the case of hydrogen-1, which is the only stable nuclide with no neutrons). The electrons of an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain bound to each other by chemical bonds based on the same force, forming a molecule. An atom containing an equal number of protons and electrons is electrically neutral, otherwise it is positively or negatively charged and is known as an ion. An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determines the isotope of the element.
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Famous quotes containing the word atom:
“Thank God! none of my children have an atom of poetry in their composition!”
—Augusta Leigh (1783–1851)
“Idealism sees the world in God. It beholds the whole circle of persons and things, of actions and events, of country and religion, not as painfully accumulated, atom after atom, act after act, in an aged creeping Past, but as one vast picture, which God paints on the instant eternity, for the contemplation of the soul.”
—Ralph Waldo Emerson (1803–1882)
“The savages don’t have atom bombs.”
—Friedrich Dürrenmatt (1921–1990)