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Isotope Class Notes

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Isotope Class Notes Subatomic Particles Label the atom: What are Isotopes? First, do you remember how to find the number of neutrons in an atom? – PowerPoint PPT presentation

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Title: Isotope Class Notes


1
Isotope Class Notes
2
Subatomic Particles
  • Label the atom

3
What are Isotopes?
  • First, do you remember how to find the number of
    neutrons in an atom?
  • Write the equation down in your notes

4
What are Isotopes
  • Isotopes are atoms that have a different number
    of neutrons.
  • An atom is still the same element if it has
    different neutrons - its just a different
    version!
  • Neutrons can be added to an atom without altering
    the number of protons and electrons it has.
  • http//www.youtube.com/watch?vYYInVraBe7s A
    Heavy Water Experiment

5
Carbon Isotopes
  • For example, the element carbon has 13 different
    isotopes!
  • You are familiar with C-12 (the C stands for
    carbon, and the 12 is its atomic mass)
  • This isotope has 6 neutrons
  • C-14 (atomic mass 14) is used for carbon dating
    and has 8 neutrons!

6
More about Isotopes
  • In an isotope, the number of protons and
    electrons never changes- only the number of
    neutrons is different
  • This means that each isotope of a particular
    element has a different atomic mass than another
    isotope of the same element
  • Remember C-12 has an atomic mass of 12 and C-14
    has an atomic mass of 14!

7
Count the Number of Protons and Neutrons
8
Isotope Notation
  • There are several different ways to write symbols
    for isotopes, each of which is perfectly
    legitimate.

The other ways to write each of these hydrogen
isotopes from top to bottom are Hydrogen-1 or
H-1 Hydrogen-2 or H-2 Hydrogen-3 or H-3
Example Write down the three different notations
for a carbon atom with 6 protons and 6 neutrons.
9
Applications of Isotopes
  • Carbon dating
  • Carbon-14 is created by the bombardment of the
    atmosphere by cosmic rays. It is an unstable
    radioactive isotope of C-12. After creation it
    finds its way into living organisms. When an
    organism dies no more C-14 is added and what C-14
    is present continues to decay. To date artifacts
    scientists compare the number of C-14 atoms to
    the more common C-12 atoms in the artifact. This
    ratio along with the half-life of radioactive
    C-14 allows dating to occur.

10
Applications of Isotopes
  • Structural determination of compounds
  • Isotopes are used to trace the formation of
    structures by acting as labels.
  • Medical Uses
  • Isotopes are used for diagnosis in medicine.
  • Sodium-24 used to trace blood flow in the body so
    that obstructions can be detected.
  • Iodine-131 has been used to test the activity of
    the thyroid gland

11
Chemistry in the Environment
  • The processing of uranium ore for nuclear fuel
    produces large amounts of radioactive mill
    tailings. Until the late 1970s disposal of the
    radioactive tailings was not controlled. As a
    result , millions of tons of these radioactive
    tailings are present in unmarked sites across the
    United States and Canada.

12
Quick Activity
  • Calculate the number of neutrons there are in the
    following isotopes (use your periodic table to
    find the atomic numbers)
  • Carbon-14
  • Nitrogen-15
  • Sulfur-35
  • Calcium-45
  • Iodine-131

13
Calculating Atomic Mass Based on Isotopes
  • Most elements exist as several different
    isotopes. For example, chlorine has two
    naturally occurring isotopes
  • chlorine-35
  • chlorine-37
  • 75.77 of the chlorine in the world exists as
    chlorine-35, and 24.23 exists as chlorine-37.

14
Calculating Atomic Mass Based on Isotopes
  • This is why the atomic masses on the periodic
    table are not WHOLE numbers.
  • If we know how much of each isotope exists in the
    world, we can calculate the average atomic mass
    of that element (which is the number you find on
    the periodic table).

15
Example
  • Chlorine exists as two different isotopes,
    chlorine-35 and chlorine-37. Given that 75.77 of
    chlorine is chlorine-35 and the other 24.23 is
    chlorine-37, calculate the average atomic mass of
    chlorine.
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