History of the Atomic Models

Trace the history of atomic models and key scientists' contributions.

NAME and GROUP Click on each blank space to complete the sentences. - An atom is the basic building block of all matter. An ELEMENT is a substance made of only one type of atoms, while a COMPOUND has different types of atoms.- An atom is formed by a nucleus found in the center of the atom, and has a positive charge; and by electrons, which have a negative charge and occupy different energy levels around the atom.- Electrons do not travel in circular orbits like a solar system; instead they create an electron cloud around the nucleus. MODEL DESCRIPTION AUTHOR Different materials have differently shaped "a-tomos" Democritus The atom is a tiny indivisible sphere. Elements are atoms with unique properties and mass, and can combine in specific ratios to form compounds. J. Dalton Discovered the electrons, as negative particles distributed throughout the atom in a positively charged substance, like fruit in a pudding. J.J. Thomson Discovered the nucleus as the positive center of an atom and electrons are distributed around it in mostly empty space. E. Rutherford MODEL DESCRIPTION AUTHOR The atom has a nucleus with protons and neutrons, while electrons travel around the nucleus in specific circular energy levels called "orbits". Niels Bohr Electrons travel around the nucleus in energy levels and sublevels with elliptic shapes Sommerfeld Electrons spin around the nucleus in an electron cloud. It is impossible to know their exact location, however denser regions called "orbitals" increase the probability of finding an electron. Schrödinger / Quantum theory