questions: Answer the following using the web resources
A. Basic nuclear chemistry:
B. Stellar chemistry and hydrogen fusion in stars:
What is the difference between chemical reactions
and nuclear reactions (in which one are new elements produced and
in which one are only new combinations of elements produced)?
Using a chemistry text or a web resource define the following:
atomic number, mass number, isotope, nuclide, fission, fusion, alpha particle,
beta particle, gamma ray, deuterium
Write the isotope symbol (includes the atomic number and
mass number) for (1) an element with 7 protons and 8 neutrons; (2) an element
with 26 protons and 30 neutrons; an element with 1 proton and 1 neutron.
(Example 136C is the isotope symbol for an
isotope of carbon with 6 protons and 7 neutrons)
Using a chemistry text or a web resource review nuclear chemistry
and write the equations for four different nuclear reactions. Show
all particles involved. One example should show alpha decay, one example
should show beta decay, one example should show fission, and one example
should show fusion.
C. The life cycle of stars
What is the most abundant element in our universe?
What are the initial "starting" particles for nuclear fusion
Why would neutral atoms not be found in a star's
interior? Describe the state in which the atoms exist in a star's interior.
Why can't molecules exist in a star?
What is the overall reaction for hydrogen nuclear
fusion in stars?
Describe and show the 3 reactions depicting each step
in the nuclear fusion in stars.
How is energy created in this process? Where
did this energy come from? What famous equation relates to this process?
In what form is the energy generated?
Since like charges repel each other, explain how two positive
protons can fuse?
Where does hydrogen fusion occur in a star? Why does
it not occur at the surface?
Compare the surface temperature of a star, such as the sun,
with the its core temperature.
At about what minimum temperature does the core of a star
need to be before fusion begins?
What are neutrinos? How are they produced? How do they interact
D. Creation of the elements
What is spectroscopy? How can this tool be used to identify
the composition of stars and nebula?
What is a "molecular cloud"? What elements and compounds
may be found in these clouds? What triggers the cloud to begin to collapse?
What is a "protostar"? What clears dust and gas around
a protostar? (be sure to find the famous Hubble Space Telescope image
of the Gas Pillars which shows protostars)
What keeps a star from continually collapsing? What
is meant by "hydrostatic equilibrium"?
Relate star color to temperature? Arrange the following
star types from coolest to hottest: yellow, blue, orange, red.
Investigate the HR diagram. Draw a labeled sketch of
this diagram. Be sure to label both axis and indicate the location of the
main sequence, red giants, supergiants, white dwarfs, the sun, and neutron
How can a supergiant be so large, but yet be relatively
How can a supergiant be relatively cool, but be very
Arrange the following in the correct sequence to depict
the life history of a star about the size of our sun:
red giant, main sequence, nebula, white dwarf, neutron star, protostar.
Explain how the life history of a star that is over
5 times the mass of our sun is different than the life history you depicted
in the previous question.
Why is the Pleides called a "stellar nursery"?
Will our sun become a red giant or a supergiant? Why?
What will be the fate of our sun: white dwarf, neutron star,
or black hole?
What will happen to the outer layers of the sun following
the red giant stage? (hint: find info on planetary nebula)
What is a supernova? What type of stars may undergo a supernova?
What exists after a supernova?
The Crab Nebula in the constellation Orion is the _____ of
a supernova that was documented by the ______ about 1,000 years ago.
Give the name of a star in our night sky that is a supergiant.
In what constellation is this star found?
What is the difference between neutron stars and black holes?
Following the Big Bang, the universe consisted almost entirely
of which element?
Why does a star's hydrogen supply in the core eventually
What would happen to a star if the hydrogen fusion process
stopped and was not replaced by any other fusion processes?
Copy and fill in the blanks: When a star's core hydrogen
supply gets low, _______ begins to fuse just outside the core.
This is called _____ "burning". This process maintains the star's hydrostatic
_______, and keeps it from collapsing. The star's size actually gets ______
at this stage and swells to the _____ stage. The fusing of the helium
with other light elements creates heavier elements such as carbon and ______
that did not exist before.
What element might be created when 2 helium nuclei fuse?
What two nuclei could fuse to form an oxygen-8 nuclide?
Copy and fill in the blanks: When an old-age star
over 5 solar masses depletes its hydrogen supply, core temperatures can
rise over 100 _____ degrees K. At these temperatures, heavier elements
such as carbon and oxygen--created by helium burning--can now fuse with
other nuclei into still heavier elements such as neon, magnesium,
silicon, sulfur, ______, ______, and _____.
Copy and fill in the blanks: These ______ reactions
continue to build larger nuclei, until a very stable nucleus is created.
This is the _____ nucleus. Even at the the incredibly high temperatures
at the core of the supergiant, this nuclei is so stable it will not fuse
with any other nuclei. This ______ (increases or decreases) the amount
of energy the star can produce. Once a relatively significant amount of
this element has built up in the star, the energy output cannot
balance the inward _____ force. At this point, the star is no longer
in hydrostatic ______ and it collapses producing a ________ implosion.
The temperatures produced during a ______implosion are so
great that now, nuclei--including the stable _____ nuclei--built
up before the implosion, can fuse to produce elements (nuclei) heavier
than iron. All the ______ heavier than iron are thus created in these implosions.
E. Summary: "We are all star stuff!"
Consider a carbon atom that is part of a protein molecule
in one of your blood cells. Could of this atom have been formed in a star
to a supernova explosion? Explain.
Consider a silver atom in a ring on your finger. How
do you know that this atom was created during a supernova?
Consider a silicon atom found in a piece of granite rock.
Through what stellar process was this atom most likely created?
As you have discovered, atoms are created in stars through
complex processes throughout the life history of the stars. Are new
atoms ever produced on earth? How?
Consider the periodic table. Which elements could be produced
in stars similar to our sun in size? (just give the range of atomic numbers;
for example: 4-12)
Again, consider the periodic table. Which elements (give
the range of atomic numbers) could be produced by supernovas?
Consider the formation of our solar system from a nebula
of gas and dust. What must have been the origin of this nebula? (Realize
that this nebula must have contained heavier elements as there are heavy
elements such as gold and lead that exist on some of the planets. )
Why can our sun be referred to as a "second generation
The astronomer Carl Sagan once stated that "WE ARE ALL
STAR STUFF". Write a brief essay to explain why this statement is true.
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