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Isotopes - What are they?

Isotopes - What are they?. A Nuclear Chemistry Introduction. Isotopes - What are they?. Find the number of protons, electrons, and neutrons for Nitrogen… What if one of these atoms had an extra neutron. Would it still be nitrogen? Why or why not? Why are the actual atomic masses decimals?.

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Isotopes - What are they?

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  1. Isotopes - What are they? A Nuclear Chemistry Introduction

  2. Isotopes - What are they? • Find the number of protons, electrons, and neutrons for Nitrogen… • What if one of these atoms had an extra neutron. Would it still be nitrogen? Why or why not? • Why are the actual atomic masses decimals?

  3. Isotopes • While the number of protons for a given element never changes, the number of neutrons can change. • An atom of the same element with a different number of neutrons is an ISOTOPE! • If the number of neutrons changes, so does the mass. Different isotopes will have different mass numbers for the same element.

  4. Isotopes What element do these isotopes represent? What about these two isotopes?

  5. Writing symbols for isotopes • How do you tell the difference between different types of the same element? • The symbol of the element is always written first then the mass number • Example: C-14 • “C” is the symbol • “-14” tells you it is an isotope with a mass of 14 • You cannot change the number of protons so you know that this carbon atom has 2 more neutrons than usual

  6. Radioactivity & Isotopes • What are radioactive elements? • Isotopes with an unstable nucleus • The nuclei of these isotopes spontaneously break apart, forming different elements • The number of protons and/or neutrons change • Why are some isotopes radioactive? • They just are, but do occur when there is a large difference between the number of protons and neutrons in the nucleus • We call them RADIOISOTOPES

  7. 8 6 Carbon 14 Stable vs. Unstable Isotopes • An atom is generally stable if the number of protons equals or is close to the number of neutrons in the nucleus. • The further apart the two numbers the more unstable.

  8. The line of stability Isotopes on either side of The valley of stability are radioactive

  9. Isotopes & sports • Floyd Landis stripped of his Tour de France title • Isotopes found in his blood came from synthetic testosterone.

  10. The number of protons (atomic number) changes 14 6 14 7 N C Losing your Identity… • Radioactive Decay causes the nucleus of an atom to change. • If the protons change it will change into a new element

  11. Radiometric Dating

  12. The abundance (percentage) of each individual isotope is multiplied by the mass of that isotope. All the individual abundances are added together This is the average mass (what is on the periodic table). Calculating the average atomic mass

  13. Element “X” Natural abundance of isotope X 10% = 4 amu 30 % = 5 amu 60 % = 6 amu 0.10 x 4 = 0.4 amu 0.30 x 5 = 1.5 amu 0.60 x 6 = 3.6 amu 0.4 + 1.5 + 3.6 = 5.5 Average mass = 5.5 amu This is the mass on the periodic table Calculating the average atomic mass

  14. Element Q 25% = 15 amu 10% = 16 amu 10% = 17 amu 55% = 18 amu Find the average mass 0.25 x 15 = 3.75 0.10 x 16 =1.6 0.10 x 17 = 1.7 0.55 x 18 =9.9 Total = 16.95 Average = 16.95 amu Practice

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