Robert Millikan's primary contribution to atomic theory came as a result of his oil-drop experiment, which measured an electron's charge. Previously, J.J. Thomson had suggested the hypothesis that an electron's mass was at least 1,000 times less than the mass of the tiniest atom. Millikan's contribution to this hypothesis was to specify the size of the electron's charge.Continue Reading
Millikan's oil-drop experiment involved spraying oil from a perfume atomizer into a sample chamber. Some of the droplets traveled through a pinhole into a space between two plates, one of which had a negative electric charge and the other of which had a positive charge. This central chamber was then ionized with X-rays. Particles that failed to catch electrons followed gravity to the bottom plate, while particles that managed to catch at least one electron floated up to the positive plate or fell at a slower rate of speed. Millikan reached the conclusion that each drop had a charge that was a multiple of 1.59 x 10^(-19) Coulombs.
Later, Millikan also verified Albert Einstein's photoelectric equation and developed the first photoelectric calculation of Planck's constant h. Later studies involved hot-spark spectroscopy of the various elements, pushing the ultraviolet spectrum far past the known lowest limit, and his motion law for a particle falling earthward after coming into the atmosphere, which led to his radiation studies.Learn more about Atoms & Molecules
An atom with no charge becomes positively charged when it loses an electron. When this happens, it is called a positive ion. If the atom gains an electron, the atom becomes a negative ion. In either case, the number of protons in the atom’s nucleus does not change. More than one electron can be removed from an atom to give it a positive charge of +2, +3 or more.Full Answer >
The subatomic particle with a negative charge is the electron. This particle was first identified in 1897.Full Answer >
Robert Andrews Millikan, an American physicist, discovered the charge carried by the electron, an elementary particle, in 1910. He made this discovery by conducting an experiment called the oil-drop experiment.Full Answer >
The molecular geometry of dichlorine monoxide is bent as a result of the lone electron pairs located on the oxygen atom. Molecular geometry is physical representation of the relation between elements in a compound.Full Answer >