Following are some Parent - Daughter isotope pairs with their half life:
U-238 going to Pb-206 (T1/2 = 4.5 x 109 years)
U-235 going to Pb-207 (T1/2 = 0.7 x 109 years)
C-14 going to N-14 (T1/2 = 5700 years)
Q-1: If the C-14 : N-14 ratio in a shell in a sandstone was found to be 1 : 3, how old is the shell?
Answer-1: _____________ years
Q-2: If the U-235:Pb-207 ratio in a rock from Massachussets was determined to be 1 : 15, how old is the rock?
Answer-2: __________years
Q-3: (a) If the U-238:Pb-206 ratio in a crystal of zircon found in a sandstone was determined to be 1 : 7, what radiometric age will this give for the zircon?
Answer-3: ___________years.
(b) Does the determined age realistic? If no why not? If yes, how? (Explain briefly).
Answer-4: ________________________.
Link to online Periodic Table: https://www.ptable.com/
Three main types of decay processes involve:
1. Alpha decay: nucleus spontaneously emits an α (alpha) particle, same as Helium nuclei, which is 2 p+ and 2 n.
Result: atomic number decreases by 2 (lost 2 p+); atomic mass decreases by 4 (lost 2 p+ and 2n = 4 amu)
2. Beta decay: neutron in nucleus spontaneously emits a β (beta) particle , which is essentially an electron trapped in a neutron. The neutron, therefore, turns itself into a proton.
Result: atomic number increases by 1 (gained 1 p+); atomic mass stays same.
3. Beta or electron capture: : proton in nucleus captures a β (beta) particle which is essentially an electron that can become part of a neutron. The proton, therefore, turns itself into a neutron.
Result: atomic number decreases by 1 (lost 1 p+); atomic mass stays same.
For example: Po-206 (atomic number = 84) with α decay makes Pb-202 (atomic number = 82)
Based on the above information, complete the following radioactive transformations ( You may need to refer to a periodic table): Please write your responses as "element symbol" followed by "atomic mass" as written in this problem itself, e.g. Boron (atomic number 5 and atomic mass 11) is written as B-11.
Be-9 + α = (1 point)
C-12 + 2 α = (1 point)
Bi-206 = _________ + β (Note: β on the product side means decay from Bi) (1 point)
Tl-202 + β = ________ (Note:β on the reactant side means nucleus captured a beta particle) (1 point)
Pu-244 = ________ + 2α + 2β (Note: there are two types of particle decaying twice) (2 point)
