Atoms & Elements Problem Set

This problem set was developed by S.E. Van Bramer for Chemistry 145 at Widener University.

  1. How many protons, neutrons and electrons are present in one atom of the following:
    1. 1H
    2. 2H
    3. 3H
    4. 13N
    5. 14N
    6. 15N
    7. 79Br
    8. 81Br1-
    9. 262Bh

  2. What is the Atomic Weight of chlorine given that: Is this the answer that you expected?

  3. What is the Atomic Weight of ruthenium given the following information from WebElements:

    Isotope Abundance Exact Mass
    96Ru 5.54% 95.907599
    98Ru 1.87% 97.905287
    99Ru 12.76% 98.9059389
    100Ru 12.60% 99.9042192
    101Ru 17.06% 100.9055819
    102Ru 31.55% 101.9043485
    104Ru 18.62% 103.905424
    Is this the answer that you expected?

  4. Using a blank periodic table, fill in the atomic number, name, atomic symbol, and atomic weight of the first 36 elements. Also label the noble gases, the halogens, the alkali metals, the metals, and the non-metals.

  5. Use the mass spectrum for chromium given below to determine the atomic weight.

Please send comments or suggestions to

Scott Van Bramer
Department of Chemistry
Widener University
Chester, PA 19013

© copyright 1996, S.E. Van Bramer
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Last Updated: Saturday, May 18, 1996