Download Chemistry Name_______________________ Chapter 4

Chemistry
Chapter 4
Name_______________________
Hour__________Date__________
Chapter 4.1 –
Early Ideas About Matter 1. What did many Greek philosophers
believe matter was composed of?
2. What did Democritus (460-370 B.C.)
believe about matter? And about atoms?
3. What was Aristotle’s (384-322 B.C.)
belief on atoms?
4. Explain Dalton’s (1766-1844)
Atomic Theory. Use Table 4.2 on p. 104.
5. How does Dalton’s atomic theory explain
the law of conservation of mass?
Chapter 4.2 – Defining the Atom
1. Define atom.
2. What instrument is used to view individual
atoms and how does this instrument work?
3. The instrument allows scientists to do what
with the atoms? (Nanotechnology, p. 107)
4. What is a cathode-ray tube (Figure 4.6)
and what has it allowed researchers to study?
5. The accidental discovery of the cathode ray
from Sir William Crookes led to the invention
of television. Explain briefly Crookes’ observations
and thus his discovery of the cathode ray.
6. Define electrons.
7. How did English physicist J. J. Thomson
(1856-1940) determine the charge-to-mass ratio
of the charged particle/electron?
8. Dalton’s atomic theory was proven false by
Thomson’s significant finding. Explain his
conclusion.
9. American physicist Robert Millikan (1868-1953)
developed the oil-drop apparatus to determine
the charge of an electron. A single electron
carries what charge?
10. How did Millikan control the rate of a
droplet’s fall?
11. How did he calculate the mass of an
electron ?
12. What explanation does Thomson’s plum
pudding model give about the charge of the atom?
13. What was the purpose of the 1911 experiment
conducted by Ernest Rutherford’s (1871-1937)
and his colleagues ?
14. Reading Rutherford’s experiment, how did
they determine if the atoms in the gold foil
deflected the alpha particles?
15. What were the results of the experiment?
16. Rutherford concluded that the plum pudding
model was incorrect. Explain his nuclear model
(Figure 4.13 ).
17. What caused the deflections?
18. Rutherford’s nuclear model introduced the concept of the NUCLEUS which contained
positively charged PROTONS. Rutherford’s coworker, physicist Chadwick (1891-1974)
showed that the nucleus also contained neutral particles called NEUTRONS. Define the
terms proton, neutron, and electron, include the symbols.
(a) Proton
(b) Neutron
(c) Electron
19. Draw Rutherford’s model of the atom (fig. 4-14)
label each part.
20. What identifies the atom of a particular
element?
21. What is the atomic number?
22. Because atoms are neutral, the atomic
number can also determine what two things
about the atom?
23. Define the term ISOTOPE.
24. How do the mass of Isotopes vary as the neutron
number changes?
25. How are isotopes of each element identified?
26. How do you determine mass number?
Write an equation that illustrates this
27. Define one atomic mass unit (amu).
28. Define ATOMIC MASS
29. How does atomic mass differ from mass
number?
(We will not be covering Sect. 4.4, p. 122-124 in this unit.)