Download Atomic Structure

WHS:CHEM1(H)
WORKSHEET:CHAPTER 4
FEBRUARY 28, 2013
Name _______________________________________________
I.
1
2
3
Matching - Match each phrase with the term that describes it best.
___1. Democritus
___2. John Dalton
___3. J.J. Thomson
___4. Eugen Goldstein
___5. Ernest Rutherford
___6. James Chadwick
___7. Neils Bohr
___8. Nucleus
___9. Proton
___10. Neutron
___11. Electron
___12. Isotope
II.
Class:
a. Discovered positively charged “canal rays” using a
modified cathode ray tube.
b. Credited with the discovery of the neutron
c. Credited with the discovery of the electron and the
“plum pudding” model of the atom.
d. Used the now famous “gold foil” experiment to
prove the existence of the nucleus. He also showed
most of an atom is empty space!
e. Credited with the “planetary” model of the atom that
shows electrons orbiting the nucleus.
f. Credited with the earliest idea of atoms existing. He
was a Greek philosopher.
g. Credited with the development of an early atomic
theory to explain the behavior of atoms.
h. Subatomic particle located in the nucleus which has
a positive charge.
i. Subatomic particle that has a negative charge
and orbits the nucleus
j. Subatomic particle that has the same mass of a
a proton, but unlike the proton, has no charge.
k. Atoms of the same element that have a different number
of neutrons (hence …different mass numbers)
l. This part of the atom houses protons and neutrons.
Short answer.
13. Describe the composition of the nucleus of an atom.
14. What does the atomic number of each atom represent?
15. What is an atomic mass unit (amu)?
4
16. How many protons are in the nuclei of the following atoms.
a. sulfur ___________
c. phosphorous _________
e. calcium ___________
b. hydrogen _______
d. cadmium _____________
f. argon _____________
III. Using a periodic table, complete the chart below:
Element
Symbol
Number of
Protons
Mass
Number
Number of
Electrons
Se
Number of
Neutrons
45
16
14
8
28
1
III.
Isotopes
16. Write the chemical symbol for the following isotopes of hydrogen.
Hydrogen-1 __________________________
Hydrogen-2 __________________________
Hydrogen-3 __________________________
Explain how these three isotopes are alike. Explain how they’re different
Complete the chart below:
Isotope
Name
Hydrogen-2
Symbol
Atomic
Number
Mass
Number
Number
of
Protons
Number
of
Neutrons
2H
1
83Sr
38
92
146
Carbon-14
8
201
80
IV. Mastery Questions and Problems:
17. Explain why the atomic mass (which is what you see on the periodic chart) for most
elements is not a whole number?
18. Compare the relative size AND relative density of atom to its nucleus.
19. Lead has 4 naturally occurring isotopes. Listed below are symbols for these isotopes along
with their percent abundance. Using this information, calculate the “average” atomic mass of
Pb. (Note: You may complete this calculation on the back of a one of the sheets in this packet).
122 Pb
82
(1.37%) :
124Pb (26.26%)
82
126
: 125
82Pb (20.82%) : 82Pb (51.55%)