Modern atomic theory has several main ideas. It holds that atoms are a constant. Chemical reactions cannot create, alter or destroy an atom. Atoms can combine to create elements, but the atomic structure of any given element is always the same. Atoms of different elements can combine to create compounds. When elements combine to create a compound, the total number of atoms of that compound is the same as the total atom count for each of those elements.
While atomic theory has evolved over the years, much of modern atomic theory is based on the work of physicists in the 1920s, who were basically the pioneers of quantum mechanics. It was in 1911 that British physicist Ernest Rutherford first proposed the nuclear atom, and Danish physicist Niels Bohr expanded on this in 1913.
One common question about atomic theory is whether or not we can actually manipulate individual atoms. Our ability to manipulate atoms dates back to the 1940s. If splitting the atom -- and causing an atomic explosion -- is a bit too uncontrolled a reaction to count as manipulation, never fear. In 1990, some engineers at IBM used a scanning tunneling microscope to nudge atoms into place. The point of the microscope was just one atom in size. What did the engineers do with the atoms? They made the world's smallest logo -- they used the atoms to spell out IBM [source: IBM].
As we learn more about atoms and how we can manipulate them, scientists hope to be able to use molecular nanotechnology in engineering, physics and medicine, even using tiny nanobots to target harmful cells like those that cause cancer [source: Jobbins].
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