3.1/3.2 Review
Name________________________________
Chemists & Models of the Atom
Period_______Date_____________________
Part I: Chemists in History - Write the name of the chemist who proposed each of the ideas listed below.
Some names may be used more than once.
Democritus
Franklin
Rutherford
Lavoisier
Thomson
Bohr
Proust
Becquerel
Moseley
Dalton
Marie & Pierre Curie
Modern Model
_____________________ 1. Stated that matter is neither created nor destroyed in chemical reactions.
_____________________
_____________________ 2. Stated that a given compound always has the same relative number and
kinds of atoms.
_____________________
_____________________ 3. Discovered radioactivity while working with a sample of Uranium.
_____________________ 4. Determined that a cathode ray is made of electrons.
_____________________ 5. Isolated two new elements, radium and polonium.
_____________________ 6. Understood the atom to have a central nucleus with electrons orbiting
around in fixed paths like planets around the sun.
_____________________ 7. Stated that all atoms of a given element are identical, but they differ from
those of other elements.
_____________________ 8. Stated that all matter is composed of tiny, indivisible particles called atoms.
_____________________
_____________________ 9. Found that there are three types of natural radiation.
_____________________ 10. First person to suggest that the atom is related to electricity.
_____________________ 11. Uses Quantum Mechanics and states that the electron may be found in a
probability region.
_____________________ 12. Determined that each atom has it own atomic number (number of protons.)
_____________________ 13. Used Gold Foil to determine that all the positive matter (protons) is
concentrated into a very small, very dense nucleus and that most of the
atom is empty space.
Part II: Experiments about the Atom – Fill in the blanks with the appropriate word. Each word or
number will only be used once.
0
+2
3
no
anode
electrons
gamma
negative
beta
empty space
large
positively
cathode
exposed
mass
proton (nucleus)
14. The negatively charged electrode of a cathode ray tube is the ___________________, the positively
charged electrode is called the ______________________.
15. In Thomson’s experiment, the cathode ray is deflected by the magnet, this indicated that the ray had
____________________. When the electrically charged plates were turned on, the cathode ray was
deflected toward the positive plate, this indicated that the beam had a ____________________ charge.
16. Therefore a cathode ray is made of a beam of ____________________.
17. Becquerel discovered radiation because a sample of uranium ore __________________ a piece of
photographic film.
18. Rutherford used a radioactive sample and determined that natural radiation has ______ components:
alpha particles which have a _______ charge and a relatively _______________ mass,
________________ particles which have a negative charge and a mass of ______ and
______________ rays which are neutral and have ________ mass.
19. Rutherford used alpha particles in his Gold Foil experiment. Because the alpha particles are relatively
large and positive the fact that most of them proceeded straight through the foil proved that the atom
is mostly _____________________________. Some of the positive alpha particles deflected directly
back toward the source which indicated that the nucleus was _______________________ charged
Thus, Rutherford is credited with discovering the ___________________.
20. Draw a simple sketch of each chemist’s model of the atom. Indicate charge where needed.
Dalton
Thomson
Rutherford
Bohr
Modern Model