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Democritus believed that atoms were uniform, solid, hard, incompressible, and indestructible. He also believed that they moved in infinite numbers through empty space till stopped. -
A Greek philosopher named Plato introduced the atomic theory which states that ideal geometric forms serve as atoms, according to which atoms broke down mathematically into triangles -
The Greek philosopher Aristotle introduced the atomic theory that there has to be something that is the source of all things. -
Lavoisier believed that matter was neither created nor destroyed in chemical reactions. -
John Dalton's experiments with gases led him to the atomic theory that all matter is composed of extremely small particles called atoms. -
The Alchemists believed that metals were formed from mercury and sulfur -
when elements are arranged in increasing order of their atomic masses. -
Mendeleev arranged the periodic table of elements in order of their increasing atomic weight. -
When electric charged particles are released from or within in a material when it absorbs electromagnetic radiation. It was discovered by Heinrich Rudolf Hertz -
Henri Becquerel Discovers Radioactivity as an accident. He opened a drawer and discovered spontaneous radioactivity. -
J.J. Thomson's experiments with cathode ray tubes showed that all atoms contain negatively charged particles or as they are known electrons. -
Planck's Quantum Theory states that different atoms and molecules can emit or absorb energy in discrete quantities only. -
The plum pudding model is a scientific model of the atom. it is defined by electrons surrounded by a volume of positive charge. it was made by J.J Thomson. -
A piece of gold foil was hit with alpha particles, which have a positive charge. Most alpha particles went right through. This showed that the gold atoms were mostly empty space. -
Rober Millikan found the correct charge of the electron using the "falling-drop method". -
The electron is the lightest stable subatomic particle and has a negative charge (1.602176634 × 10−19 coulomb) -
A structural model of the atom in the model the electrons travel around the nucleus of the atom in distant circular orbits or shells -
Henry Moseley discovered that the atomic number on periodic table is the number of positive charges in the atomic nucleus -
The proton was discovered by Ernest Rutherford his research resulted in a nuclear reaction which led to the first splitting of the atom, where he discovered protons. -
Schrodinger's Equation is a linear partial differential equation that governs the wave function of a quantum-mechanical system. -
It is a principle that states that we cannot know the position or speed of a particle accurately. It was formulated by Werner Heisenberg. -
James Chadwick founded the neutron by knowing that most of the mass of an atom was in the nucleus, so he found that there was uncharged particle in the nucleus.