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422 BCE
Democritus Model
Democritus’s model stated that matter consists of invisible particles called atoms and a void (empty space). He stated that atoms are indestructible and unchangeable. Also that they are homogeneous, meaning they have no internal structure. His atomic model was solid, and stated all atoms differ in size, shape, mass, position and arrangement, with a void exists between them. His ideas were based on reasoning rather than science. -
Dalton Model
John Dalton came up with a theory on the smallest particles in the universe, of what makes up what we call "matter". Dalton created the "Law of Multiple Proportions". This states that the weights of elements always combine with one another in ratios of small whole numbers. Dalton experimented with a gas called nitric oxide (NO) and oxygen (O). He reacted them together to produce a third type of gas. The results were determined by the proportions or ratios of the two reacting gasses. -
Thomson Model
Thomson's work suggested that the atom was not an "indivisible" particle as John Dalton had suggested but a jigsaw puzzle made of smaller pieces. Thomson's notion of the electron came from his work with a nineteenth century scientific curiosity: the cathode ray tube. Thomson found that the mysterious glowing stream would bend toward a positively charged electric plate. Thomson theorized that the stream was in fact made up of small particles, pieces of atoms that carried a negative charge. -
Rutherford Model
Rutherford proposed that atoms consisted of a small dense center filled with positive charges. He named this center the nucleus. He then said that negatively charged electrons were scattered surrounding this dense, positively charged center. He stated these negatively charged electrons were held in orbit by the positively charged nucleus, due to the electrical forces. -
Rutherford's experiment
Rutherford performed a series of experiments with radioactive alpha particles.Rutherford shot tiny alpha particles at solid objects such as gold foil.He found that while most of the alpha particles went through the gold foil,a small number of alpha particles went through and some bounced back.Rutherford's experiments suggested that matter in general,had holes in it.These holes allowed most of the alpha particles to pass through,while a small number bounced back because they hit a solid object. -
Bohr model
Atomic structure Developed by Danish physicist and Nobel laureate Niels Bohr (1885–1962). n atomic physics, the Rutherford–Bohr model or Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system. -
Schrodinger Model
Schrodinger discovered that electrons don't move in orbits (or in a set path at all). He theorizes electrons move in waves, and they have no exact location. Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. This model introduced the concept of sub-energy levels.
