History of an Atom

• Dalton Billard ball (1800) - thought atoms as small, hard sphere balls that couldn't be split up
• Thomas's “Plum pudding” model (1897) - shows electrons embedded in a positive charge sphere
• Rutherford's “Nucleur” model (1911) - describes them as a positively charged nucleus with electrons. Discovery of the  protons
• Bohr Model (1912) - electrons orbit the nucleus. Discovery of “electron shells”
• Quantanium Mechanical Model (1926) - The center of an atom is a nucleus made from protons and neutrons. Believed that electrons orbit the nucleus in electron shells