Unit 1 Standards Review

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

Atomic and Nuclear Chemistry



  1. Students know how to relate the position of an element in the periodic table to its atomic number and atomic mass.

    • The atomic number equals the number of in the nucleus of the atom. The atomic number of carbon is .
    • The atomic mass of an atom that has five protons, six neutrons and five electrons is . It is an atom of the element .
    • An atom of nitrogen must have protons. It must also have electrons. If it has eight neutrons, then the atom is nitrogen-.

  2. Students know the nucleus of the atom is much than the atom yet contains most of its .
  3. The nucleus is composed of tightly packed protons and .
  4. Protons have a charge of and a mass number of . Neutrons have a charge of and a mass number of .
  5. Electrons are found in the electron . It is nearly massless, but occupies most of the of the atom.
  6. Electrons have a charge of and a mass number of .

  7. Students know protons and neutrons in the nucleus are held together by the strong forces that overcome the electromagnetic repulsion between the .

  8. Students know the energy release per gram of material is much in nuclear fusion or fission reactions than in chemical reactions. The change in mass (calculated by E = mc2) is small but significant in nuclear reactions.

  9. Students know naturally occurring isotopes of elements are radioactive, as are isotopes formed in nuclear reactions (man-made isotopes).

  10. Students know the three most common forms of radioactive decay (a, b, and g) and know how the nucleus changes in each type of decay.

  11. When an atom loses an alpha particle, the mass number decreases by and the atomic number decreases by .

  12. When an atom loses a beta particle, the atomic number increases by as a is converted into a .

  13. Students know alpha, beta, and gamma radiation produce different amounts and kinds of damage in matter and have different penetrations.


    • The least penetrating and least damaging of the three is radiation
    • The most penetrating and most damaging of the three is radiation