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:
“The flame from the angel’s sword in the garden of Eden has been catalysed into the atom bomb; God’s thunderbolt became blunted, so man’s dunderbolt has become the steel star of destruction.”
—Sean O’Casey (1884–1964)
“We have grasped the mystery of the atom and rejected the Sermon on the Mount.... The world has achieved brilliance without wisdom, power without conscience. Ours is a world of nuclear giants and ethical infants.”
—Omar Bradley (1893–1981)
“Truth is one, but error proliferates. Man tracks it down and cuts it up into little pieces hoping to turn it into grains of truth. But the ultimate atom will always essentially be an error, a miscalculation.”
—René Daumal (1908–1944)