1. More on the Atomic Model B/t Rutherford’s & Bohr’s models: it was hypothesized that electrons orbited the nucleus, just not in a fixed orbit The problem: if the orbitals aren’t fixed then the electrons will just fall into the nucleus because + and – attract Bohr proposed fixed orbits to fix that problem

2. More on the Atomic Model Quantum mechanics: explains how particles behave (on very tiny scales) This is in contrast to classical mechanics used to explain how everyday objects work Key idea of QM proposed by Louis de Broglie: matter behaves as particles & waves (wave- particle duality)

3. De Broglie’s Atom

4. Heisenberg & Schrödinger The key contributors to the current electron cloud model of the atom (among others who contributed to QM such as Planck, Einstein, de Broglie) – Heisenberg’s uncertainty principle: can’t precisely know position & momentum at the same time – Schrödinger’s wave equation: calculates the probability of the location of a particle

5. Schrödinger’s Cat Schrodinger was confuzzled by the QM notion of superposition proposed by Einstein & co. Superposition: a particle simultaneously exists in all its possible states until observed or interacts with the external world – E.g. e - has both up and down spin states until observed Proposed a thought experiment to demonstrate how ridiculous superposition was

6. Schrödinger’s Cat Cat in box Box has container filled w/ HCN (poison) HCN triggered by decay of radioactive substance Amount of substance is so tiny that over an hour 1 atom may decay (w/ equal chance of not decaying)

7. Schrödinger’s Cat

8. Possible states of the radioactive substance: decayed and not decayed…and as a result the cat will be dead and not dead Superposition states that these states simultaneously exist until observed So until the box is opened, cat is alive and dead (“living & dead cat mixed or smeared out in equal parts” in Schrödinger’s words)

9. Atomic Structure

10. LocationCharge mass (AMU) Mass (kg) ProtonIn nucleus+1 (positive)~11.67262178 x 10 -27 NeutronIn nucleus0 (neutral)~11.6749 x 10 -27 Electron In orbitals outside of the nucleus -1 (negative)~09.10938291 x 10 -31

11. Elementary Particles

12. The Higgs Boson Can explain why certain particles have mass while others do not Can explain how mass is generated, how the universe came to be massive Existence confirmed at the Large Hadron Collider (LHC)

14. Large Hadron Collider

15. Key Terms Atomic number = # of protons (determines what the element is!) Mass number = # of protons + neutrons (not the same mass as the one on the periodic table) Charge = difference b/t protons & electrons – e.g. if there are 10 protons and 11 electrons… Charge = 10(+1) + 11(-1) = 10 - 11 = -1 Ions: atoms or molecules with a charge – Cations: + ions – Anions: - ions

16. Nuclear Notation Try writing the following in nuclear notation: Nitrogen atom, Cl -, Mg 2+, carbon-14

17. Isotopes Isotopes of an element have different # of neutrons and therefore masses E.g. Carbon-12 is the most common isotope of carbon on earth. C-13 ( 13 C) and C-14 ( 14 C) are other isotopes. Atomic mass (on the periodic table) is a weighted average of all the isotopes of an element using their % abundance

18. Remember Carbon Dating? Radioactive 14 C is made in the atmosphere Combines w/ O 2 to make CO 2 CO 2 taken in by plants for photosynthesis Animals eat plants & acquire radiocarbon until they die at which point they stop acquiring 14 C and it undergoes radioactive decay Can be used to measure up to 50,000 years in the past ( 14 C half-life ~5730 years)

20. Calculating Atomic Mass E.g. calculate the molar mass of carbon given the following table

21. Calculating Atomic Mass 12.000000 x 0.9893 + 13.003355 x.0107 = 11.8716 + 0.1391358985 = 12.0107359 = 12.01

22. PhET Simulations 1)Hydrogen Atom 2)Rutherford Scattering 3)Isotope 4)Build an Atom Play around, visualize what you’ve learned. #4 make sure you do the quiz!

23. HW for Tomorrow On the website Print it out, copy it out or email it