Physical Science

Elements in the Universe and the Atom

Lesson 1: Know Your Universe

How It All Began

• Process called “Inflation” – explosively rapid expansion of space occurred. Pairs of matter and antimatter (quarks and antiquarks) were formed from energy – pairs were cancelled back (annihilation).

• Nucleosynthesis or nuclear fusion – as the universe cooled down , an excess matter (electrons, protons, neutrons and other particles) that came into highly energetic “plasma soup”. Protons and neutrons came together and form different types of nuclei.

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• Recombination – known as the “dark ages” where electrons started to bind to ionized protons and nuclei forming neutral atoms and that bound particles move freely across the space.

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• As atoms particles collapse due to gravity – to formed stars, and galaxies and eventually other matter.
• Discovery of Redshift – space itself is expanding in all directions causing all the galaxies to be relatively farther apart.

- first piece of evidence for the Big Bang Theory.

Lesson 2

We are made from the stars

• Stellar Nucleosynthesis – reactions that happened inside the stars where hydrogen and helium atoms began combining in nuclear fusion reaction –Fusion resulted in the formation of nuclei of new elements.

The first fusion process occurs in the hydrogen core of stars such as the sun with temperature of less than 15 million K. – this kind of stars are called main-sequence stars

Fusion Process

• Proton-Proton Chain

• 3 entire step process releases about 26.7 MeV (mega electronvolts)
• The energy release is responsible for the thermal pressure that pushes against gravity.

• CNO Cycle

• Core of the star comprised of HE as H is depleted, while H fusion only occurs in a shell around it.
• Various nuclear fusion occur in red giant star
• Alpha Fusion process continue via the alpha ladder.
• CNO cycle – as the main sequence stars hotter than 15 million K and that facilitate the production of helium, once carbon was present from alpha processes, carbon is used as a catalyst in carbon fusion cycle or CNO cycle.

• Supernova Nucleosynthesis
• As the star unable to generate energy to push against gravity due to the formation of heavy elements –cause to collapse on itself, undergoes a supernova explosion that synthesize elements heavier than iron.
• Thorium and uranium are just some of the heaviest elements and this is done by the r-process and s-process.

R-process

- Involves rapid capture of neutrons by the atom

S-process

- Involves slow neutron capture in red giants.

Chris Impey, professor of astronomy at the University of Arizona – implies that since carbon, nitrogen and oxygen atoms are found in our bodies and because humans and every other animal as well as most of the matter on Earth contain these elements, we are literally made of the star.

Lesson 3

Ancient Greek’s Concept of Atom

Atom - It is the smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical