1. What is an _________? The smallest particle of an ________ that is still an ________ _________ are the building blocks of all ___________

2. Atomic Theory according to … THE GREEKS Early _________ believed matter was made from the four elements of earth, ______, water and ____ Wind Earth Fire Water

3. Atomic Theory according to … DEMOCRITUS Greek with a different __________ on what matter was made of Proposed that there is an _________ particle He called the particle an atomos, which means __________ Born: 460 BC Died: 370 BC

4. Atomic Theory according to … John Dalton He performed many ___________ to understand why elements combine the way they do Formulated the __________ Theory His theory has been __________ to integrate the findings of other _________ Born: 1766 Died: 1844

5. Dalton’s Atomic Theory All substances are made of ______. Atoms are small particles that cannot be created, divided or ___________. Atoms of the same element are exactly _________. Atoms of different elements are ___________. Atoms join with other atoms to make ____ substances.

6. Atomic Theory according to … J.J. Thomson Discovered smaller, _______ particles inside the atom through the cathode- ray tube experiment Born: 1856 Died: 1940

7. Atomic Theory according to … J.J. Thomson The particles were negatively charged particles called ___________ Dalton’s atomic theory was revised to account for electrons Plum _________ Model of Atom after discovery of electrons

8. Ernest Rutherford He tested Thomson’s plum pudding model by aiming a beam of _________ particles at a piece of gold foil Born: 1871 Died: 1937

9. Atomic Theory according to … Ernest Rutherford Rutherford’s findings suggested that the plum pudding model was _________! Atomic model was revised to include a _________ + + + + - - - - ______ _______

10. Atomic Theory according to … Neils Bohr Suggested that _______ travel around the nucleus in a definite _____ Born: 1885; Died: 1962

11. Modern Atomic Theory The current model of an atom contains a nucleus surrounded by regions called electron __________ Electrons do not travel in specific paths, and the _______ path of an electron cannot be _____________ The electron clouds are the regions an electron is likely to be _________

12. Electron Cloud Model

13. Subatomic Particles Subatomic particle SymbolCharge Mass Location Protonp+_____ ______ Neutronnº_________________ Electrone-______ ______ amu _______ Cloud