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    HW 7 Answer Key

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    angelyn martinez
    Isotopes are atoms of the same element that have differing numbers of neutrons, giving them different masses. The document provides data on isotopes of several elements, including their atomic number, mass number, number of protons, electrons, and neutrons. It asks students to name each isotope with its symbol and mass number, determine how isotopes of the same element differ, compare mass number to average atomic mass, and calculate average atomic masses for several elements based on the natural abundances of their isotopes.

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    HW 7 Answer Key

    Uploaded by

    angelyn martinez
    368 views2 pages
    Isotopes are atoms of the same element that have differing numbers of neutrons, giving them different masses. The document provides data on isotopes of several elements, including their atomic number, mass number, number of protons, electrons, and neutrons. It asks students to name each isotope with its symbol and mass number, determine how isotopes of the same element differ, compare mass number to average atomic mass, and calculate average atomic masses for several elements based on the natural abundances of their isotopes.

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    Hw 7 answer

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    Isotopes are atoms of the same element that have differing numbers of neutrons, giving them different masses. The document provides data on isotopes of several elements, including their atomic number, mass number, number of protons, electrons, and neutrons. It asks students to name each isotope with its symbol and mass number, determine how isotopes of the same element differ, compare mass number to average atomic mass, and calculate average atomic masses for several elements based on the natural abundances of their isotopes.

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    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
    Download as doc, pdf, or txt
    368 views2 pages

    HW 7 Answer Key

    Uploaded by

    angelyn martinez
    Isotopes are atoms of the same element that have differing numbers of neutrons, giving them different masses. The document provides data on isotopes of several elements, including their atomic number, mass number, number of protons, electrons, and neutrons. It asks students to name each isotope with its symbol and mass number, determine how isotopes of the same element differ, compare mass number to average atomic mass, and calculate average atomic masses for several elements based on the natural abundances of their isotopes.

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    of 2

    Name _________KEY_____________ Date _____________

    Class __________________________ Mr. D’Amico

    Homework # 7

    1) What is an isotope? How is it different from an ion?

    Isotopes are atoms of a given element (same amount of protons) but have
    differing amounts of neutrons. The varying amount of neutrons causes the
    isotopes to have different masses.

    2) A chemistry laboratory has analyzed the composition of isotopes of several


    elements. Data for one of isotopes of the elements is given in the table below.

    Element Atomic Mass Protons Electrons Neutrons Symbol Name


    Number Number
    22
    neon 10 22 10 10 12 Ne Neon-22
    46
    calcium 20 46 20 20 26 Ca Calcium-46
    17
    oxygen 8 17 8 8 9 O Oxygen-17
    57
    iron 26 57 26 26 31 Fe Iron-57
    64
    zinc 30 64 30 30 34 Zn Zinc-64
    204
    mercury 80 204 80 80 124 Hg Mercury-
    204

    a) Determine the number of protons, neutrons, and electrons in each


    isotope.

    b) Name each isotope (including mass number) and give its symbol
    (including mass number).

    3) How do isotopes of the same element differ? Give specific examples.

    Isotopes have different amounts of neutrons, and therefore different masses. For
    example, argon-40 has 22 neutrons, while argon-42 has 24 neutrons.
    4) Compare mass number and average atomic mass.

    The average atomic mass is the weighted average of the masses of all of the
    isotopes of an element. The mass number refers to the mass of one of those
    elements, and is always a whole number.

    5) Silver has two isotopes, 107Ag has a mass of 106.905 amu (52.00%) and 109Ag
    has a mass of 108.905 amu (48.00%). What is the average atomic mass of
    silver? Box your answer.

    (106.905)(.5200) + (108.905)(.4800) = 107.86 amu

    6) Chlorine, which has an average atomic mass of 35.453 amu, has two naturally
    occurring isotopes, chlorine-35 and chlorine-37. Which isotope occurs in
    greater abundance? Explain.

    Chlorine-35 is in greater abundance due to the weighted average atomic mass of


    35.453 amu.

    7) A scientist investigating an element used for medical technology found that it


    has 2 naturally occurring isotopes: one has a mass of 6.015 amu that occurs at
    7.5% abundance; the other has a mass of 7.016 amu and occurs at 92.5%
    abundance. Identify the element based on its average atomic mass. Box your
    answer.

    (.075)(6.015) + (.925)(7.016) = 6.94 amu; the element is lithium.

    8) Titanium has 5 naturally occurring isotopes:


    a) titanium-46 occurs at 8.0%
    b) titanium-47 occurs at 7.30%
    c) titanium-48 occurs at 73.80%
    d) titanium-49 occurs at 5.50%
    e) titanium-50 occurs at 5.40%
    Calculate the average atomic mass of titanium. Box your answer.

    (.08)(46) + (.0730)(47) + (.7380)(48) + (.0550)(49) + (.0540)(50) =

    3.68 + 3.431 + 35.424 + 2.695 + 2.7 = 47.93 amu

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