radio carbon dating

1. ABHIYATRIK DEY
BANKURA UNIVERSITY
REGISTRATION NO- 17139 of 2018-19
UID NO- 18003014014
INTERNAL ASSIGNMENT [107 I.A]

2. RADIOCARBON
DATING
14C

3. Lets Start. . .

5. WHAT IS RADIOCARBON DATING OR 14C DATING ?
Radio carbon dating a technique used by scientist to learn
the ages of biological specimens.
For example, wooden archaeological artifacts or ancient
human remains- from the distant past. It can be used on
objects as old as about 62,000 years.

6. Assumption made by W. Libby for accurate
determination of age
1
• Decay occurs at a constant rate
2
• Ratio of 14C to 12C has remain constant

7. WHAT IS AN ISOTOPE ?
An Isotope is what scientist call two or more forms of the same
element.
If you could peer at the atom of two different atom of two different
isotopes, you’d find equal numbers of neutron in the atom’s nucleus
or core.

8. Isotopes of Carbon
Carbon Isotopes comes in three form. By far the most common isotope of Carbon is
Carbon-12 (12C) which contain six neutron in addition to its six proton. The next heaviest
Carbon Isotopes is carbon-13 (13C) has seven neutron. Both 12C & 13C are called stable
isotopes since they do not decay into other forms or element over time. The rare
Carbon-14 (14C) isotope contain eight neutron in nucleus, this isotope is unstable or
radioactive over time, a 14C atom will decay into stable product 14N.
Nuclei and Relative abundance of Carbon Isotopes
98.9% 1.1% < 0.00001%

9. 14
N Neutron capture
14
C
All three isotopes of carbon, are
absorbed by living organism
Cosmic
radiation
Proton
Animal and
people eat plants
and take carbon-
14
Following death and burial, wood and bones lose C-14 as it
changes to N-14 by beta decay
Beta decay
14 14
Beta particle
Proton Neutron

10. DETERMINATION OF AGE
We know that,
N = N 0 e -Kt
N/ N 0 = e –Kt
or, In (N/ N 0 ) = -Kt
or, 2.303 log 10 (N/ N 0 ) = - t ⨯ 0.693/ (t ½) C-14
or, t = - [ 2.303⨯ (t ½ ) C-14 / 0.693 ] ⨯ log 10 (N/ N0)
or, t = [ 2.303⨯ (t ½ ) C-14 / 0.693 ] ⨯ log 10 (N 0 / N)
(14C/12C ratio in the living organism)
or, t = [ 2.303⨯ (t ½ ) C-14 / 0.693 ] ⨯ log 10
(14C/12C ratio in the dead organism)
N= (14C/12C ratio in the
dead organism)
N0 = (14C/12C ratio in the
living organism)
t = age of the organism
K = disintegration constant

11. 100
12.5
25
50
5730 2292011460 17190
14 C
atom
Years
PLOT : If A0 and An are activities at time zero
and after n half life period
respectively then,
An = A0 (0.5) n

12. !
SUMMARY
• Carbon-14 can only be used to date organic material.
• Carbin-14 dating accuracy is dependent upon a
consistent ratio between C-12 and C-14.
• The assumption of equilibrium is FALSE.
• There are factors that can affect C-14 in the atmosphere .
• Ancient fossils as well as coal contain C-14 residue.

13. THANK YOU
REFFERENCE : earthsky.org/earth/what-is-radiocarbon-dating
Inorganic Chemistry by R.Sarkar
Dr. Susovon Bhowmik & Dr. Prabir Ghosh, Bankura University