Atomic Theory History 1-10 Flashcards
What is a model and how are they used? Include at least 3 examples of models.
A representation of an idea in order to make it more understandable. Examples: 1- a drawing, 2- a physical representation, 3- a set of symbols (letters)
Explain why we will never see an individual atom an how we do get images of them.
We see visible light and the size of this light is much too large to hit individual atoms often enough to bounce back to our eyes. Without this, our eyes can’t form an image. We get images of them from an STM microscope
Explain Aristotle’s theory of atomic history. Use a green (fresh) stick to explain the parts.
All matter is composed of 4 things: earth, air, fire, and water. Fresh stick: earth=ash, air=smoke, fire=fire, water=sap
Explain 5 things about Democritus’s model of the atom.
Atoms are hard, solid, individual and indivisible particles. Shape of atoms is responsible for their properties.
John Dalton (1803) explained atomic theory by the billiard ball model. Explain at least 4 parts of Dalton’s model.
1- indivisible
2- hard
3- sphere
4- atoms did not split or combine, they just rearranged.
J.J. Thomson (1897) created the cathode ray tube. Explain what he discovered about the atom and describe his model. Also explain how he determined this using the CRT.
He proved that atoms had parts: positive and negative. His model: chocolate chip cookie model- chips=negative
Cookie=positive.
Negative must equal positive
Ernest Rutherford is famous for the gold foil experiment, explain his procedure, what parts of the atom he discovered and his new model of the atom.
He used a radioactive rock to send alpha positive particles through a very thin piece of gold foil to see how they would come out the other end. He discovered the nucleus. His new model said that all of the positive particles were in the middle (nucleus) and negative electrons surrounded them.
Niels Bohr, in 1913, added to Rutherford’s model. Explain what he said about the orbits of electrons? How accurate was he compared to the modern model?
The electrons orbit the nucleus like the planets orbit the sun. Very accurate.
Explain the modern model of the adom. Include the parts that make up the Adam, where they are located, they are masses, their charge, and what makes them up.
The electron cloud model (modern model) represents the area where the electrons are most likely to be found. Mass-location-charge-made of
Proton: 1 Nucleus +1 uud
Neutron: 1 Nucleus 0 udd
Electron: 0 Electron cloud -1 Nothing
Explain how Dmitri Mendeleev created the periodic table. Include what he did that was amazing and showed his genius ability.
He created cards for all of the DISCOVERED elements. Organized them in a pattern that he saw. Left blank cards for UNDISCOVERED elements, and predicted the physical properties of the NOT YET DISCOVERED element.
