UNIT 3 REVIEW WORKSHEET

Part 1 - Fill in the blanks

Atoms are made up of electrons, which have a   1  charge;                  1. ________________
, which have a positive charge; and   3  , which are neutral.             2. ________________
The latter two particles are found in the   4  of the atom.                     3. ________________

It was   5  who discovered the nucleus of the atom.  The                     4. ________________
nucleus has a   6  charge and it occupies a very small volume               5. ________________
in the atom.
In contrast, the negatively-charged   7  occupies              6. ________________
most of the volume of the atom.
7. ________________

The number of   8  in the nucleus of the atom is the atomic   9             8. ________________
of that element.
Because the atom is electrically neutral, the               9. ________________
number of protons and   10  are equal.  The sum of the   11                10. ________________
and neutrons is the mass number.  Atoms of the same element are       11. ________________
identical in most respects, but they can differ in the number of              12. ________________
12  in the nucleus.  Atoms that have the same number of protons       13. ________________
but different mass numbers are called   13  .

The   14  of an element is the weighted average of the masses of         14. ________________
the isotopes of that element.
Two isotopes of sulfur are 32S and            15. ________________
34S.
An atom of the sulfur-32 isotope contains   15  protons and            16. ________________
16  neutrons.  The sulfur-34 isotope has   17  protons and   18           17. ________________
neutrons.
18. ________________

Each of the three known isotopes of hydrogen has   19  proton(s)          19. ________________
in the nucleus.
The most common hydrogen isotope has   20               20. ________________
neutrons.
It has a mass number of   21  and is called hydrogen-1.        21. ________________

Part 2 - Solve the following problems.
22. Calculate the average atomic mass of oxygen given the percent abundance of each of its naturally-
occurring isotopes:  oxygen-16 is 99.76%, oxygen-17 is 0.037%, and oxygen-18 is 0.204%.

23. What is the mass of 6.00 moles of aluminum?

24. How many moles contain 8.53 x 1023 atoms of platinum?

25. How many atoms of carbon are in 3.25 moles of carbon?

26. How many moles of SO2 are in 160.0 grams of SO2?

27. What is the mass of 3.58 x 1024 atoms of nitrogen?

28. How many molecules does 80.0 grams of K2O contain?

Part 3 - Fill in the following chart.

 Name # of e- Atomic # Mass # # of no # of p+ Symbol arsenic - 76 27 58 48 36 11B 25 56 8 6 7 7

Answers to # 23 - 28:
23.) 162 grams        24.) 1.42 moles        25.) 1.96 x 1024 atoms        26.) 2.500 moles
27.)
83.2 grams        28.) 5.13 x 1023 molecules