Pick up your science journal. This week’s feedback distributer. Atomic Theory Pick up your science journal. This week’s feedback distributer.

Rutherford’s Gold Foil Experiment Deflection of beam’s particles (1899) Box contains redioactive polonium Some passed straight through, beam’s particles deflected

Scanning Tunneling Microscope (1981) Sharp probe which conducts electricity When the probe hits an atom, the flow of electrons between the atom and the probe changes

Create a timeline Create a timeline which illustrates the following: John Dalton, J.J. Thomson, Ernest Rutherford, Niels Bohr and two other scientists of your choice! The dates they introduced their development A brief description of the development for each person A drawing of each model References: Look at pages 61 – 65 of textbook Keep track of all the sources that you use! I will request a citation on your poster.

EQ: What is the fundamental basis of matter? Atomic theory EQ: What is the fundamental basis of matter? TODAY: Check back to your beginning of the year goal: Are you meeting your goal? Why or why not? Hold onto your lab report This week’s feedback distributer: Paula & Shahrouz ANNOUCEMENT: Redo opportunities – quiz, myths Google drive submission – myths, lab

To do today Complete a self assessment of your lab report. Submit with your lab attached. Finish atomic theory timeline Begin isotopes mini research Your grade thus far – mini meeting

Early ideas about matter About 2500 years ago, Greek philosophers though that air, earth, fire and water were elements that formed all matter Was matter endlessly divisible or indivisible?

John Dalton (1803) All matter is made up of atoms. Atoms are indestructible and cannot be divided into smaller particles. All atoms of one element are exactly alike but they are different from atoms of other elements Evidence: Elements combine in the same percent by mass every time the same compound is formed

JJ Thompson (1897) Atoms composed of subatomic particles that are negatively charged Plum pudding model: electrons in a ball of positive charge

JJ Thompson Evidence: Cathode ray Vacuum tube, electrode (metal piece), high voltage When electrodes are charged, rays travel from the negative electrode (cathode) to the positive (anode). Therefore, known as cathode rays. Apply electric field: Rays bent toward positively charged plate Cathode rays made up of electrons

Ernest Rutherford (1909) Small densely charged particle called the nucleus Evidence Lead shielded box containing radioactive polonium, which emits fast-moving positively charged particles Gold foil surrounded by screen Observations: when beam struck the gold foil, some particles passed through while others deflected