1. The document discusses the Big Bang theory and the formation of light elements during the early universe. It describes how nucleosynthesis produced hydrogen, helium, and small amounts of lithium and beryllium from nuclear fusion of protons and neutrons in the first few minutes after the Big Bang. 2. The correlation between predicted and observed abundances of hydrogen and helium provided major evidence for the Big Bang theory. Measurements of unprocessed gas in parts of the universe and meteorites confirmed the predicted abundances. 3. Big Bang nucleosynthesis involved nuclear fusion reactions that combined protons and neutrons into light atomic nuclei like deuterium and helium-4 isotopes over time as the universe rapidly expanded

1. Lesson 1.1
The Big Bang Theory and the
Formation of Light Elements

2. Objective give evidence for and
explain the formation of the
light elements in the big
bang theory.
1
At the end of
the lesson,
you should
be able to:

3. Learn about It!
Cosmology is the body of science that studies the origin,
evolution and eventual fate of the universe
Cosmology

4. Learn about It!
Religious Cosmology
• Religious or mythological cosmology explains the origin
of universe and life based on religious beliefs of a specific
tradition
• The concept of creatio ex nihilo
• God creating the universe as written in the book of
Genesis
Cosmology

5. Learn about It!
Physical Cosmology
Physical cosmology explains the origin of universe based on
scientific insights, studies and experiments
• Nicolaus Copernicus and the heliocentric nature of the
universe
• The expanding universe through Albert Einstein’s theory of
relativity
• The big bang theory
Cosmology

6. Learn about It!
The big bang theory, a cosmological model that describes how
the universe started its expansion about 13.8 billion years ago,
states that the universe continues to move and expand
Big Bang Theory

7. Learn about It!
1. The universe began as a singularity or a point containing
all space, time, matter and energy
2. It expanded rapidly in nothingness through a rapid yet
peaceful process called inflation
3. The universe cooled down as it expanded
Big Bang Theory

8. Learn about It!
4. A soup of matter in the form of subatomic particles was
formed and nuclei of light atoms were created via
nucleosynthesis or nuclear fusion between protons and
neutrons
5. Electrons interacted with these nuclei to form actual,
primordial atoms via the process of recombination
Big Bang Theory

9. Learn about It!
Evidences
1. Vesto Slipher and Carl Wilhelm Wirtz (1910)
• Measurement of redshift
• Observed that most spiral galaxies were moving away
from the earth
2. Georges Lemaître (1927)
• Proposed alternative idea that the universe is expanding
Big Bang Theory

10. Learn about It!
Evidences
3. Edwin Hubble (1929)
• Calculated distances between the earth and several
galaxies using redshift of light
• Observed distant galaxies were moving away from the
Earth and one another
Big Bang Theory

11. Learn about It!
Evidences
4. Robert Wilson and Arno Penzias (1965)
• Discovered cosmic microwave background radiation
(CMBR)—a low, steady humming noise believed to be
energy remains
5. Modern astronomy (2014)
• Universe is estimated to be 13.8 billion years old with 5%
of its composition existing as ordinary matter
Big Bang Theory

12. Learn about It!
Big Bang Nucleosynthesis
• Big bang nucleosynthesis (BBN), also known as
primordial nucleosynthesis, is the process of producing
light elements during the big bang expansion
• It yields two stable isotopes of hydrogen, two isotopes of
helium, some lithium atoms and beryllium isotopes
Big Bang Theory

13. Learn about It!
Big Bang Nucleosynthesis
1. A proton (p) and a neutron (n) may fuse together to yield a
high-energy photon (γ) and an isotope of hydrogen (H)
called deuterium (D or 2H, with one p and one n)
• The deuterium bottleneck can be traced to its low binding energy and
eventual destruction by photons at very high temperatures
• A decrease in temperature enabled deuterium to stabilize and
eventually initiate the BBN cascade
Big Bang Theory

14. Learn about It!
Big Bang Nucleosynthesis
2. Two D nuclei may fuse together to form either of the
following:
a. The radioactive H isotope tritium (T or 3H, with one p and two n) and
one p; or
b. The isotope helium-3 (He-3 or 3He, with two p and one n) along with
one n
Big Bang Theory

15. Learn about It!
Big Bang Nucleosynthesis
3. Helium-4 (He-4 or 4He, with two p and two n) may be
formed from three fusion reactions
a. The fusion of one p and a T atom
b. The fusion of D with T
c. The fusion of D with He-3
Big Bang Theory

16. Learn about It!
Big Bang Nucleosynthesis
• He-4 has a binding energy of 28 MeV, and further fusion
products were a rarity since these resulting atoms had binding
energies lower than this aforementioned amount
Big Bang Theory

17. Learn about It!
Big Bang Nucleosynthesis
4. He-4 may still undergo further fusion in the presence of a T
atom, yielding the lithium-7 atom (Li-7 or 7Li, with three p
and four n) and a γ
• Li-7 may react with one p to produce two stable He-4 nuclei
Big Bang Theory

18. Learn about It!
Big Bang Nucleosynthesis
5. He-4 may also fuse with He-3 to yield the unstable isotope
beryllium-7 (Be-7 or 7Be, with four p and three n) along with
one γ
Big Bang Theory

19. Learn about It!
The nuclear reactions as predicted by the big bang nucleosynthesis.

20. Learn about It!
• The correlation between predicted and observed cosmic
abundances of H and He was the major proof of the big
bang theory
• Almost all available neutrons have combined with protons, forming 24%
He-4 by mass
• About 74% H by mass remained uncombined
Big Bang Theory

21. Learn about It!
• To verify these observations, scientists measured
abundances of primordial material in unprocessed gas in
some parts of the universe with no stars as well as in parts
of meteorites known as chondrites that commonly fall to
Earth
Big Bang Theory

22. Key Points
The big bang theory is a cosmological model that
describes how the universe started its expansion about
13.8 billion years ago.
1
Big bang nucleosynthesis is the process of producing
light elements during the big bang expansion.
2
The correlation between the predicted and observed
cosmic abundances of hydrogen and helium was the
major proof of the big bang theory.
3

23. Check Your Understanding
Complete the following nucleosynthesis diagram:

24. Challenge Yourself
Why is a neutron released during the fusion of two
deuterium atoms?

25. Bibliography
Clayton, D.D. 1968. Principles of Stellar Evolution and Nucleosynthesis. Chicago, USA: University of Chicago
Press.
Constan, Z. “Learn Nuclear Science with Marbles.” National Science Foundation 2017. Accessed July 13,
2018. http://www.jinaweb.org/outreach/marble/Marble%20Nuclei%20Project%20-
%20Activities%20Student%20Worksheet.pdf
Langer, N. “Nucleosynthesis.” Bonn University SS 2012. Accessed December 8, 2016. https:// astro.uni-
bonn.de/~nlanger/siu_web/nucscript/Nucleo.pdf
National Aeronautics and Space Administration. “The Big Bang.” Accessed December 8, 2016.
http://science.nasa.gov/astrophysics/focus-areas/what-powered-the-big-bang/
National Geographic. “Origins of the Universe—An Expanding World.” Accessed December 8, 2016.
http://science.nationalgeographic.com/science/space/universe/origins-universe-article/

26. Bibliography
Overton, Tina, et al. 2010. Shriver and Atkins’ Inorganic Chemistry. 5th ed. London: Oxford University Press.