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History of the Atom
Question | Answer |
---|---|
What did William Crookes discover? | Cathode Rays |
True or False: Cathode Rays come from the Anode | False |
Are Cathode Rays positive or negative? | Negative |
Cathode rays are invisible. Identify 3 more things we know about Cathode Rays | 1.They fluoresce when they hit glass 2. They travel in straight lines 3. They have enough energy to make a paddle move |
Who discovered the electron? | JJ Thompson |
Who identified the ratio of charge to mass (e/m) of the electron | JJ Thompson |
Describe the plum pudding model of the atom proposed by JJ Thompson | A mass of positively charged material with small negative charges (electrons) embedded in it. |
Who worked with Cathode Rays first, Crookes or Thompson? | Crookes; Thompson followed on from Crookes' work |
What did Robert Millikan calculate? | The charge on an electron |
What did Millikan charge in order to measure the charge of an electron? | Oil drops |
State the 3 assumptions of Dalton's Atomic Theory | 1. All matter is made of very small particles 2. Atoms are indivisible, they cannot be broken down 3. Atoms cannot be created or destroyed |
Name the scientist who discovered the nucleus | Rutherford |
What experiment did Rutherford carry out? | Shot alpha particles at a thin sheet of gold foil |
What was the expected result of Rutherford's experiment | The alpha particles would pass straight through the atoms, with slight reflections |
What was the actual outcome of Rutherford's experiment | Some alpha particles were reflected at large anlges or back along their own path |
What did Rutherford's experiment demonstrate? | A dense core of positive matter existed in the centre of each atom- the nucleus! |
What was Rutherford's second discovery? | The proton |
How did Rutherford discover the proton? | Bombarded many elements with alpha particles and positive charges were emitted from the nuclei of lighter elements |
Who discovered the neutron? | Chadwick |