Download Unit 5 - Stars

Don’t spill the beads!!!
 How do stars differ from moons and
planets, and from one another?
4. Complex Knowledge:
demonstrations of
learning that go
aboveand above and
beyond what was
explicitly taught.
 How does the classification of stars
help us understand how they evolve
over their lifetimes?
3. Knowledge: meeting
the learning goals and
expectations.
 What are the different types of
2. Foundational
knowledge: simpler
procedures, isolated
details, vocabulary.
stars?
 What happens when different types
of stars die?
 Why is it important for us to
understand stars?
1. Limited knowledge:
know very little details
but working toward a
higher level.
Draw this on your paper
 Use the whole page
Take 15 Marshmallows out of
the cup
 Each marshmallow represents one proton
 Each bead represents one gamma particle
(photon\energy)
 Take 15 Marshmallows (protons) out of the cup
 Put them all in the “Hydrogen” quadrant
 Write down how many there are
 Take 10 beads (gamma particle) out of the cup
 Set them off to the side
Model a main sequence star
Your hands are now the core of a star where huge
temperatures and pressures exist
Use this temperature and pressure to fuse together
Hydrogen nuclei (protons) into Helium nuclei
For each helium atom created, place one bead next
to it
Continue this until all your Hydrogen supply is gone
Write down how many Helium atoms there are
Leave the 7 beads in the Helium quadrant. At this
point 5 beads (energy) have been created in your
Helium section. These are released in the form of
heat.
Model an older star
 In older stars, much of their hydrogen has been converted into
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helium. If the temperature gets high enough, the cores of these
stars can continue fusion through the triple-alpha process. To
model this, take two of your helium nuclei (also called alpha
particles) and smash them together. This forms a very unstable
beryllium atom.
If a third helium nucleus hits it before it disintegrates, a new
element with six protons is formed. Smash another of your
helium nuclei into your unstable beryllium atom. What element
have you created?
Place it in the correct quadrant
For each carbon atom created, place a bead next to it
Write down how many atoms of carbon there are
 Once all of the Carbon has been created, you have
now created a Red Giant star – with atoms of
Hydrogen, Helium, and Carbon along with energy.
 Make sure you have filled out:
 Write the number of atoms that were formed for each
element
 Hydrogen Helium Beryllium
 Carbon How many gamma particles (photons) wre produced?
End
 Please make sure the beads end up back in
the cups
 Please make sure the marshmallows end up
in your belly or the trash!
Analysis on google classroom
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9.
What is the name of the process by which stars generate energy?
Atoms of which element are found at the beginning of this
process?
By the end of this activity, atoms of which two elements have
been created?
What is released as a result of this process?
What pattern arose during this activity (Hint: look at the
numbers)
What can be inferred about the formation of heavier elements in
stars? Hint: think quantity
Large amounts of energy are released when nuclei combine.
How many energy-producing reactions did you model?
Why are Boron and Lithium generally not fused in a star?
What is the atomic mass of Hydrogen? What is the atomic mass of
Helium?
Hydrogen and Nuclear fusion
Record (draw, label, write) each step of
the process.
https://www.youtube.com/watch?v=W1ZQ4JB
v3-Y
Change in mass
 When atoms fuse to form larger atoms, there is often
a mass difference between the input atoms and the
output atoms.
 Two 2H atoms can combine to form one 4He.
 The mass of two 2H atoms is 2x2.01=4.02
 The mass of one 4He is 4.o0.
 The loss (.02) is converted into energy. (EMR)
Conservation of Mass and Energy
 In nuclear reactions, some mass is always
converted to energy, so it seems that mass is
lost, but the combination of mass and energy
is ALWAYS conserved.
The basic formula for fusion is:
4 1 1 H  4 2 He + energy
*Atomic number= protons
*Atomic mass= protons + neutrons
How to calculate energy released:
1
4
1H
4

2 He +
energy
1. calculate total mass of the reactants
and products
2. calculate the difference in mass to find the deficit
3. convert mass to energy. (E=mc2)
1
H = 1.007825 amu
4 He = 4.002603 amu
2
1
How to calculate energy released:
1
4
1
H
4
2
He + energy
1. calculate total mass of the reactants and products
2. calculate the difference in mass to find the
deficit
3. convert mass to energy. (E=mc2)
4 1 1H - 4 2He
4.0313 amu - 4.002603 amu = .028697
How to calculate energy released:
1
4
1H
4

2 He +
energy
1. calculate total mass of the reactants and products
2. calculate the difference in mass to find the deficit
3. convert mass to energy. (E=mc2)
c= 3X 108 m/s
Mass 1 amu= 1.66 X 10-27 kg/amu
Mass deficit = .028697 amu
Answer:
E= mc2
E=.028697 amu (1.66X10-27kg/amu) (3x 108)2
E=4.3 X 10-12 Joules
 .0000000000043 J
Update your sketch from yesterday…
Fusion is when two elementary
particles collide
and combine or fuse to
make -- even temporarily -a new particle. A form
(isotope) of hydrogen Tritium - collides with
another form of hydrogen Deuterium - to form a new
particle. The fused particle
is not stable, and quickly
decays into a very fast
moving (hot) neutron , a
helium nucleus , and
energy.
Update your sketch
Summing it up…
1. Summarize the equation E= mc2 and
describe why it’s important. Also discuss
the potential if we were able to convert
mass directly to energy.
Homework: Due tomorrow!
http://www.pbs.org/wgbh/nova/einstein/experts.html
•Listen to 3 scientists describe the importance of
E=mc2
•Record their name and 1-2 sentences
summarizing their thoughts on the equation, how
it relates to stars, and why it’s important.