2. Atomic Structure Where our ideas of the atom come from and what we know now

3. Dalton’s Theory Elements made of INDIVISIBLE atoms Atoms of an element IDENTICAL Different element, atoms have different masses Compounds are atoms of more than one element

4. Where Dalton was wrong Atoms NOT indivisible Atoms of element NOT identical Atoms of different elements have more different than just their masses

5. Then we talk about J.J. Thompson Part of the atom is the ELECTRON –Electron is negative –Deflected by magnetic field Led to the Plum Pudding model –Think of raisin bread –Charges evenly spread out

6. Ernest Rutherford Shot alpha particles at gold foil –Alpha particles are basically helium atoms –Like elephants being thrown at tissue paper

7. What he expected Most alpha particles pass straight through Few slightly deflected Gold atoms are reasonably large

8. Rutherford’s Gold Foil Experiment

9. Another view of Gold Foil Experiment

10. What he got Most particles went straight through Very few deflected just a little bit Some even deflected A LOT! More amazing – some bounced BACK!!!

11. What does this all mean The atom has a small, dense core with a positive charge The atoms is MOSTLY EMPTY SPACE!!! Center to be called – the Nucleus

12. The next level of understanding The Bohr Model –Accepted the experiments of Thompson –Nucleus in the middle with electrons around it

13. What could he add to it? Electrons exist in ENERGY LEVELS Energy Levels = ORBITS (like planets) They do not live in between Specific amount of energy to move Quanta Absorb energy to move up, release energy to move down

14. Wave-Mechanical Model Uses ORBITALS Orbitals = Probability maps Show where the electrons are in the structure of the atom The problem: –Particles –Waves

15. Orbitals

16. Structure of the atom Protons Neutrons Electrons ParticleMassChargeLocation Proton1 a.m.u.+1Nucleus Neutron1 a.m.u.0Nucleus Electron1/1836 a.m.u. Outside Nucleus