1
answer
0
watching
228
views
18 Nov 2019

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)

For unlimited access to Homework Help, a Homework+ subscription is required.

Nelly Stracke
Nelly StrackeLv2
4 Mar 2019

Unlock all answers

Get 1 free homework help answer.
Already have an account? Log in
discord banner image
Join us on Discord
Chemistry Study Group
Join now

Related textbook solutions

Weekly leaderboard

Start filling in the gaps now
Log in