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The alchemists believed that all metals were formed from two principles — mercury and sulfur -
Solid forms of matter are composed of indivisible elements shaped like triangles. He believes triangles must be the correct form because they can join together to make very different kinds of shapes. -
He believed atoms were uniform, solid, hard, incompressible, and indestructible and that they moved in infinite numbers through empty space until stopped. -
He didn’t believe in the atomic theory and thought that the stuff on earth wasn’t all made from atoms except for Earth, Air, Fire, and water. He thought that all substances were made from small amounts of all four elements of matter. -
He believed that everything was composed of very tiny particles, an idea known as atomism. -
All matter was comprised of indivisible and indestructible atoms with distinct masses and properties, the combination of which determined the physical nature of their constituent elements. -
If the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements. -
Mendeleev arranged the elements in order of increasing relative atomic mass. It is the number of times heavier an atom is than one-twelfth of a carbon-12 atom. -
When electrons are ejected from the surface of a metal when light is on it. -
The radioactivity of uranium was discovered in 1896 by Henri Becquerel. He accidentally discovered that uranium salts spontaneously emit a penetrating radiation that can be registered on a photographic plate. -
Planck proposed that the energy of light is proportional to frequency, and Planck's constant (h) is the constant that relates them. -
The plum pudding model has electrons surrounded by a volume of positive charge, like negatively charged "plums" embedded in a positively charged "pudding". The plum pudding model of the atom The current model of the sub-atomic structure involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. -
Millikan's work demonstrated that electrons did have a discrete, quantifiable charge. -
The experiment was a piece of gold foil was hit with alpha particles and those have a positive charge, most of the particles went through, which meant that most of the gold atoms were mostly empty space. -
The electrons encircle the nucleus of the atom in specific allowable paths called orbits. When the electron is in one of these orbits, its energy is fixed. -
In 1914 Moseley published a paper in which he concluded that the atomic number is the number of positive charges in the atomic nucleus. -
The discovery of the proton is credited to Ernest Rutherford, who proved that the nucleus of the hydrogen atom is present in the nuclei of all other atoms in the year 1917. -
A linear partial differential equation that governs the wave function of a quantum-mechanical system. -
The uncertainty principle states that we cant know the position and speed of a particle, such as a photon or electron with perfect accuracy. -
In May 1932 James Chadwick announced that the middle contained a new uncharged particle that he called the neutron.