History of the Discoveries Related to the Atom Mrs. Paul Atomic Theory History of the Discoveries Related to the Atom Mrs. Paul

Main Contributors To Atomic Theory 450 BC 1800 1897 1901 1910 1911 1913 Planck: Quanta, predictable packets of energy Millikan: Charge on the electron of -1 Rutherford: atoms have a nucleus Bohr: Proposed a model of an atom Dalton: Wrote an Atomic Theory with 4 main ideas Thompson negative charge in the atom Democritus: Matter made of tiny things called ATOMS 1924 1926 1926 1932 1962 Chadwick: neutrons Debroglie: Matter has a wave-like nature Heisenberg: E- are waves and particles Gell-Mann: Quarks Schrödinger: E- travel in waves

Timeline of Atomic Theory 450 BC 1800’s _________________________________________________________ Dalton: proposed 4 components to an Atomic Theory. Democritus: matter was made of “atoms”

Dalton’s Theory: Foundation of Future Investigations All matter consists of tiny particles. Atoms are indestructible and unchangeable (Has been modified with recent discoveries in nuclear chemistry) Elements are characterized by the mass of their atoms. When elements react, their atoms combine in simple, whole-number ratios. Their atoms sometimes combine in more than one simple, whole-number ratio. Click the picture to explore more about experiments related to Dalton’s theory.

Atomic Theory 1897-1962 Sub-Atomic Particles ___1897________ 1910________ 1911_________1913________1932________1962___ Thomson Cathode Ray Experiment Negative charge in the atom Millikan Oil Drop Experiment Charge on e- is 1- Rutherford Gold Foil Experiment Alpha Particles and Nucleus Animation Nucleus Bohr Bohr Model Bohr’s Discovery Quantum Model Chadwick History of Chadwick Neutron Gell-Mann What are p+ and n0? Quarks

3 Basic Parts of the Atom. Click on this link and participate in the interactive questions

Quarks = up (+2/3) and down (-1/3) Gluon forces between quarks Types of Quarks Determine Charge http://nobelprize.org/educational_games/physics/matter/1.html Quarks = up (+2/3) and down (-1/3) p+ = 2ups and 1 down n0 = 2 down and 1 up +2 +2 -1 = +1 -1 -1 +2 = 0 3 3 3 3 3 3 Gluon forces between quarks

Energy Nature of Matter 1900-1926 ____________1905______1924_____1926______1926__ 1900 Planck Quantum Hypothesis Atoms Absorb and Emit Light Photo Electric Animation Quanta Einstein Matter and Energy different forms of the same thing E=mc2 Explained E=mc2 De Broglie Wave nature of matter Heisenberg Uncertainty e- acts as a wave and a particle Schrodinger e- orbits as a wave

Are they a particle or a wave? Electrons…….. Are they a particle or a wave?

Electrons travel in waves Click this link for explanation

Electrons as Waves Electrons travel in discreet packets called photons which travel in waves. To describe these unique packets or quantities of energy the term “quanta” is used. Every element on the periodic table is made up of atoms with a unique signature of spectral lines. Click the picture below

Electron behavior as it moves to other energy levels. This emitted energy is equal to the difference between the high and low energy levels, and may be seen as light. Click the picture for animation

Electrons as a Particle having position in an Atom Electrons are particles with a charge of 1- , it has mass, and its position can be predicted with reliability. Bohr proposed 4 characteristics to predict the position of an electron. l = the distance from the nucleus m = the shape of the orbital in which the e- occupies. (s,p,d,f) n = axis the orbital occupies. (x, y, z) s =spin of the e- (+1/2 , -1/2)

1. Distance from the nucleus Levels 1-7: When looking at the periodic table, can be determined by the period number. 1 2 3 4 5 6 7

2. Shape of the Orbital 3. On the x,y,z Axis The # of electrons in a particular region determines the shape. s shape 2e- p shape 6 e- d shape 10 e- f shape 14 e-

Atom with overlapping orbitals

4. Spin of the Electron

Electrons exhibit particle and wave like behavior called “Duality” Click here for animation

Einstein vs Bohr Bohr: Predictability Einstein: causality If you know the initial conditions and you know the laws of physics, you can figure out the probability of various outcomes happening, but you can never know which one will definitely occur until after it’s over. If you know all the initial conditions of your system and you know the laws of physics, you can figure out exactly what’s going to happen

Particles of the Atom to date: Nucleus Protons = p+ = 3 quarks Neutrons= n0 = 3 quarks Electron Cloud Electrons =e- (particle/wave) http://www.youtube.com/watch?v=ol_FrffMoQ8 http://www.youtube.com/watch?v=45KGS1Ro-sc http://www.youtube.com/watch?v=fm7oGOdsaQk http://www.teachersdomain.org/asset/lsps07_vid_stability/   Held together by a force called : Gluon