Symmetry
reflection symmetry
1. Mirror Image symmetry
2. Rotational symmetry
3. Transverse (90 degree) symmetry
4. Cis-trans (180 degree) symmetry
5. Diffference between a chiral molecule and its mirror image
6. Inflation is the biggest example of 90 degree rotational symmetry
7. The universe expands uniformly in all directions
180 degree rotational symmetry
8. What is an octahedron
How are they related
A cube has 4-fold rotational symmetry, an octahedron has 3-fold rotational symmetry
They are duals of each other
So if you cut out a square from a piece of paper and folded it into a cube, then you can unfold that same square and it will make an octahedron
Or vice versa if you start with an octahedron and cut out squares from the corners it will make a cube
9. What is chirality
Chirality refers to molecules that are not their own mirror images, or "chiral"
DNA is chiral because if you lined up two strands they would not match up perfectly like strands of rope would
There's more to it than this but this is the basic idea
Some examples of chiral molecules are amino acids and sugars, etcetera
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10. Describe how to draw the Fischer projection for a molecule where there is NO mirror image symmetries (aka “chirality”)
Then use simple rules for drawing circles so that they look round when viewed from above, etcetera
This gives you Fischer projections for any non-chiral molecule
11 : How do you draw a chair projection for a molecule with no mirror image symmetries
Draw it as described above for Fischer projections but also draw horizontal lines going across at 45 degrees instead of straight across so that these 45 degree lines intersect with vertical lines at 90 degrees instead of 0 degrees
12 : How do you draw an anti-Fischer projection
Draw horizontal lines going across at 0 degrees instead of 45 degrees so that these 0 degree lines intersect with vertical lines at 180 degrees instead of 90 degrees
13 : What does it mean when I say "molecules have different intermolecular forces"
When two molecules stick together strongly then they have strong intermolecular forces whereas weak intermolecular forces means weak binding between molecules (like oil floating on water)
Strong bonding means stronger molecular structure which means higher boiling point and lower melting point compared to weaker bonding which means weaker molecular structure which results in lower boiling point and higher melting point since heat energy can break apart weaker bonds easier than stronger ones
14 : Why does temperature affect intermolecular forces
Temperature affects intermolecular forces because higher temperatures cause faster movement among molecules which means more collisions among them which causes them to stick together more since their electrons move around more freely causing positive charges on one side to attract negative charges on another side due to electrostatic force
15 : How does pressure affect intermolecular forces
Pressure affects intermolecular forces by increasing molecular movement caused by increased kinetic energy due to increased pressure , thus causing more frequent collisions among molecules resulting in stronger intermolecular forces
16 : Why do gases expand when heated
Gases expand when heated because
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