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42 Cards in this Set
- Front
- Back
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Who came up with the term atom?
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Aristotle
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What does the word atom come from? What does it mean?
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Greek, Uncuttable (indivisible structures)
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What did Alchemists (groups of scientists) do?
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1) added substances together to see what happened
2) Broke substances down (EX: they tried to make lead out of gold) |
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What did John Dalton do?
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constructed the first model of the atom
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What did John Dalton's model of the atom look like?
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Just a plain sphere. Nothing inside of it, just a circle.
PICTURE (dont know if this works or not): http://edu.glogster.com/media/10/41/89/35/41893510.jpg |
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What were the four fundamental facts that Dalton came up with?
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1) all matter is composed of atoms
2) an atom can't be divided into anything simpler (smaller) 3) Atoms of the same element are identical 4) Different elements are made up of differenet kinds of atoms |
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Some of the facts that john dalton came up with turned out to be false, which ones were they?
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2) an atom can't be divided into anything smaller (atomic bomb)
3) Atoms of the same element are identical (isotopes, BUT they are identically chemically, just not exactly) |
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Even though everything is made of atoms, some are made of ______ of ______ kinds
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combinations, different
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What did William Crookes discover?
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Cathode Rays are some sort of particles,
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Why did Crooke's conclude that cathode rays are particles?
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He did an experiemtn involving a glass bottle, a cross, and electrodes (anote and cathodes). When the tube was connected to a battery, a cathode ray was emitted and it left a shadow where the cross was (technically behind it... blah blah). He concluded that some sort of particles were being emitted and were blocked by the cross, causing a shadow
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What did J.J. Thomson contribute to the understanding of cathode rays?
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He said that cathode rays are negative particles.
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How did Thomson prove that cathode rays are particles?
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He held a magnet up to the bottle and the beam bent in the direction of the magnet. A ligh ray wouldn't bend like that with a magnet, the beam had to be made up of charged particles.
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What was THomson's model for the atom called?
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Plum Pudding
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What did Thomson's plum pudding model look like?
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It was this big circle with little charged particles inside of it. Thomson said that the atom is charged somehow
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What do the plum's in the plum pudding model represent?
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electrons
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What did Ernest Rutherford do? How?
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He disproved Thomson's Plum Pudding Model. He was doing the gold leaf experiment and aiming alpha particles at some sort of sheet of paper thing. and then they hit a screen which had a burst of light. It resulted in some of the particles going straight and some veering off at large angles. This was unexpected because if thomson was correct, only some of the particles would be deflected, and not by much. This proved that there had to be something more in an atom that was big enough to deflect the alpha particle.
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What was the difference between ernest rutherford's atom and thomson's?
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it had a nucleus with electrons orbitting it
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What did Niels Bohr contribute to the understanding of the atomic structure?
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he said that electrons travel around the nucleus in a distinct orbit and his work helped inspire more research on the atomic structure
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Compared to other forms of matter, what is special about an element?
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It is made of only one kind of atom
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What does the atomic number represent?
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The number of protons in an atom
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What are isotopes?
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atoms of the same element that have different numbers of neutrons
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The mass number of an atom represents what?
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the number of protons and neutrons in an atom
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What is the release of nuclear particles and energy called?
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radioactive decay
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Changing one element to another by means of radioactive decay is called....
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transmutation
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What does an alpha particle consist of?
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2 protons and 2 neutrons
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What is an electron that comes from the nucleus called?
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beta particle
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What is a "half life"?
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the amount of time it takes for half of a sample of a radioactive element to decay
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What is the purpose of carbon dating? What do you use to make it happen?
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to determine the age of artifacts and dead plants and animals. It's a process by means of radioactive decay
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What is an element that is man made and does not exist naturally?
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synthetic element
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How does an atom decay?
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either by the release of alpha particles, or the release of beta particles
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Atoms with an unstable nucleus are ____
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radioactive
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What does radioactive mean?
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the atom releases particles from the nucleus
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What is another name for alpha particle decay?
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Transmutation
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Describe transmutation
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An atom gives off an alpha particle. It loses 2 protons and two neutrons. This changes the identidy of the atom (protons) and also changes the mass by four (4 nucleons)
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Describe the process of losing beta particles.
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A beta particle is the electron part of a neutron. If the neautron losses the electron, it is no longer a neutron. It is now only a proton. This changes the identidy of the element (proton), BUT it does not change the mass number because the mass doesnt change. (proton just substitutes for former-neutron)
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What is a neutron composed of?
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it's a prton and an electron fused together.
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How would Rutherford's experiement have come out differently if the atom was really like dalton had thought?
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You would have much more rickashaying and most of the AP would be sent back towards the direction they came
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How would Rutherford's experiment have come out different if the atom was like thomson's "plum pudding" model?
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There would be very little deflection and most of the particles would pass straight through
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In the new way to write a chemical symbol, where would you put the mass number? the atomic number?
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In superscript next to the element name.
ex: Carbon: C 12<---mass # 6<--- atomic # |
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What does it mean if an atom is "unstable"?
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they have a different number of protons and neutrons and they are radioactive
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What is radioactivity?
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emission of energetic particles from unstable atoms
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Who do unstable atoms release particles?
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to make atoms stable
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