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In 1898, J. J. Thomson found that the positive charge of a hydrogen ion was equal to the negative charge of a single electron. [ 70 ] In an April 1911 paper concerning his studies on alpha particle scattering, Ernest Rutherford estimated that the charge of an atomic nucleus, expressed as a multiplier of hydrogen's nuclear charge ( q e ), is ...
Leucippus was the first Western philosopher to develop the concept of atoms, but his ideas only bear a superficial resemblance to modern atomic theory. Leucippus's atoms come in infinitely many forms and exist in constant motion, creating a deterministic world in which everything is
Democritus and Lucretius denied the impossibility of a vacuum, being of the opinion that there must be a vacuum between the discrete particles (atoms) of which, they thought, all matter is composed. In general, however, the belief that a vacuum is impossible was almost universally held until the end of the sixteenth century. [ 41 ] ...
Thus, iron atoms are solid and strong with hooks that lock them into a solid; water atoms are smooth and slippery; salt atoms, because of their taste, are sharp and pointed; and air atoms are light and whirling, pervading all other materials. [3] It was Democritus that was the main proponent of this view.
This became the classic means of measuring the charge-to-mass ratio of the electron. Later in 1899 he measured the charge of the electron to be of 6.8 × 10 −10 esu. [32] Thomson believed that the corpuscles emerged from the atoms of the trace gas inside his cathode-ray tubes. He thus concluded that atoms were divisible, and that the ...
For Democritus, the only true realities are atoms and the void. What we perceive as water, fire, plants, or humans are merely combinations of atoms in the void. The sensory qualities we experience are not real; they exist only by convention. [7] Of the mass of atoms, Democritus said, "The more any indivisible exceeds, the heavier it is."
An orbital is the "cloud" of possible locations in which an electron might be found, a distribution of probabilities rather than a precise location. [62] Each orbital is three dimensional, rather than the two-dimensional orbit, and is often depicted as a three-dimensional region within which there is a 95 percent probability of finding the ...
Thomson later found that the positive charge in an atom is a positive multiple of an electron's negative charge. [23] In 1913, Henry Moseley discovered that the frequencies of X-ray emissions from an excited atom were a mathematical function of its atomic number and hydrogen's nuclear charge.