MATS 3011 Lecture 10: Nobody’s Perfect

Yesterday in MATS 3011 lecture, we talked about crystal defects. When crystals form, they condense into a specific structure. These structure are represented by the 14 Bravais lattices and each has its own unique placement of atoms in reference to another atom.

We went over point defect and its three variation. The first one is vacancy where there is a void where an atom should be. The second one is interstitial where there is an addition of extra atom where there SHOULDN’T be an atom. And the third one was substitutional, where a foreign atom replaces an atom of the crystal type.

In the class note, Prof. Holmes told us that real crystals always have defects. They are unavoidable. And the case is the same as us, humans. We are not perfect. We have faults here and there.

Just as a vacancy point defect, we always lack certain good traits (here represented as each atom in the crystal). We just don’t have them. Maybe because we were never taught about them.

Like a substitution point defects, we have some ‘bad’ traits in place of the good traits.

And like interstitial point defects, we might have good traits that are not supposed to be there. Maybe because even though we think it’s a good trait, we just didn’t do it in the right place.

However, these defects can be beneficial. In example, semiconductor needs defects in order to have their electrical properties. Thanks to substitution defect, semiconductors have brought advancement to our technology (i.e. computer chips).

The case is the same with us. By not being perfect, we can complete each other. Hence, interaction between humans are created. By interaction, we bring advancement. I can’t imagine if everyone in the world is perfect. Nobody will need help from another. Everyone will live on their own because they don’t need anyone else.

Defects are a good think, ain’t it?

MATS 3011 Back To High School

You know that feeling when you’re in a class in high school and you JUST want to sleep, thinking “this class won’t be any use for me anyway”?

Well, I have to admit that I have actually thought about that. But in this case, it wasn’t that bad.

I had a MATS 3011 lecture today. We are covering diffraction for crystal analysis and identification. Diffraction? Yes. We started the lecture by covering Young’s double slit experiment.

Hmm… I think I’ve heard that before…? Oh yeah… Sure… Sometime in high school, 10th or 11th grade… Marthen Kanginan book… Physics…

Memories flashed through my mind: how i remember reading through that chapter in high school, the super confusing explanation in the textbook, the formula derivation, the pictures, and how I, well, hate love it. LOL

Thankfully, I remembered everything. I understood the explanations because I still remember all of it. What surprised me most is that I have not encountered this for a long long LONG while and it never occured to me that I would need the concept again.

It turns out that element crystal structure can be identified using this method. If you shoot x-ray to a crystal, the small separation between atoms will cause the x-ray to be diffracted. And based on the interference of the diffraction and the light-dark pattern on the screen, we can determine the separation length and how it was built.

So the x-ray (= light = a pack of photon = energy!) hit the atoms and excited their electrons. When the electrons re-ground, they re-emit energy too, which is equal to the x-ray energy.

Each atom then act as a point source that emits photons (aka light) to all direction, interferencing with photons from other atoms, and create the patterns.

Although this process is quite different from Young’s double slit experiment, I’m glad I paid attention back in highschool. Because now I have a solid background understanding to help me in this class. =)

How Fast Do You Boil?

The 3rd and 4th lecture of MATS 3011 mainly talked about types of bonding. The class divide the bonds into three groups: Primary Bond, Secondary Bond, and James Bond.

No, just kidding. The last one didn’t count.

Anyways, primary bonds are molecular bonds that has chemical properties. It involves sharing or transfer of electrons. Primary bonds consist of three bonds:  ionic bond, covalent bond, and metallic bond.

Ionic bond is basically a coulombic attraction between a positive and negative ion after a transfer of electron. Covalent bond is sharing of electron. Metallic bonds, on the other hand, use a ’sea’ of electrons to ‘glue’ the positive atom nuclei together.

Secondary bonds, however, are physical. They mainly involve dipole (two poles, + and -) attractions.

Now, on to James Bond. James Bond is a fictional secret agent character. It was created by Ian Fleming in 1953….

Do I need to say all these?

But anyways, all those bonds determine the properties of chemical compounds, mainly their melting point and boiling point. The stronger the bond, the higher the temperature needed to melt/boil the chemical.

Now, imagine you and your best friend (strong bond). Even if you tease that friend (give an energy) a little bit, the friend will not get angry (won’t boil right away). But if you do that to a somebody you don’t know (weak bond between you and him/her), a little teasing can kill you!

So, how fast do you boil?

MATS 3011 Lecture 2: Everlasting Legacy

Building an everlasting legacy is very hard. You need hard work and perseverance for that. In the world of matters, there are three who made it.

At the age of 26 (1911), Niels Bohr made a new stepping stone towards a further understanding of matter at an atomic scale. He proposed that electrons revolve around the nucleus in discrete orbitals. His basic idea is that the angular momentum of electrons around the nucleus is quantized, meaning that the orbits can only be at certain radius from the nucleus.

This happens because if the electron gets closer than the ’stable radius’ r₀, there is a repulsion energy from the nucleus, pushing the electron away. On the other hand, if the electron gets too far, there is an attraction energy, which brings the electron back to the ’stable radius’.

Ten years later (1921), Louis De Broglie, who was 29 years old at that time, proposed a new and, at that time, “bizzare” idea. It was already thought at that time that light has both wave and particle-like properties. So he just flipped it and said that matter also has a wave-like property. And he derived an equation and solve it for Bohr’s proposal that angular momentum of electrons IS quantized.

But if matter has a wave-like property, there has to be the wave function, right?

Yes. In 1926, Erwin Schrodinger found this equation at the age of 39. His wave equation presents the probability of finding the electron at a radius r from the nucleus. Because it is a probability, then electron CAN actually deviate from it’s ’stable radius’. Only that the probability is very very low. That’s also why we can’t pinpoint the position of an electron. The only thing we can say is that the electron is ‘very probable’ to be at this position, or orbit at this ’stable radius’ r₀ from the nucleus.

My point here for this post is that, these three people, along with probably more others, has changed the view of physics into the age of quantum physics. They have changed the world with their thoughts since a relatively young age.

Now, can we, the young generations, change the world with our own thoughts, even if it means moving away with a new concept that might still sound bizzare to others? Are we brave enough to defend what we believe? Can we create a legacy for our own?

Below is a picture I took from my lecture notes:

Great people…

MATS 3011 Lecture 1: Studying Chocolate

Chocolate has been estimated to have around 800 compounds in it, give or take a hundred, depends on where it came from. Among those 800, 35% consist of fat (long chain hydorcarbon molecules), 50% sugar, and 15% other stuff. The fat and sugar molecules are what makes chocolate taste YUM YUM!!!!

Now, lets take a cocoa butter. Cocoa butter is a mixture of triglycerides. Here’s a picture of it:

Except that one in chocolate, first ‘leg’ is palmitic acid {CH₃(CH₂)₁₄COOH}, second one is oleic acid {CH₃(CH₂)₇CH=CH(CH₂)₇COOH}, and third one stearic acid {CH₃(CH₂)₁₆COOH}. Long chains, huh?

Now, what do you notice when you first eat chocolate? Sweet? Of course! But what else? It MELTS!!!! Why? It means that the melting point of chocolate is slightly between room temperature (27 degree C) and body temperature (36-37 degree C). That’s why chocolate doesn’t melt before you eat it.

If you tilt your head to the left, you will notice that the molecular structure looks like a jelly fish. LOL But this brings a question, what does chocolate crystal look like?

or ? Others?

Well, looks more likely to be the left one because there are too many intermolecular interaction at the second one which means very high melting point. But there are still many others. My professor said that there are scientists that study chocolate for their career. LOL So nice…

Now, there are 6 known chocolate forms, all affecting their melting points. They depend on certain conditions of cooling process after reheating.

1. The first form is obtained when, after heating, the chocolate was cooled fast (also called fast quenching). This will result in chocolate that has a melting point of 17 degrees C.
2. The second form is obtained if the heated chocolate was cooled with the rate of 2 degrees C per minute. This will result in melting point of 23 degrees C.
3. The third one is if you do it like the second one, but then leave it for quite awhile. It can also be said that the second structure decays. This results in melting point of 25.5 C.
4. If you ‘freeze’ it at 20 degree C, the result chocolate will have melting point of 27 degree C.
5. If you freeze like number 4, but do it while shearing (stiring) it, you will get the best chocolate ever. LOL This chocolate have melting point of around 33.8 degree C. And this type is what most chocolates we eat are made through.
6. Now, like number 3, if you make a chocolate through form 5 and keep it in storage for awhile, it also decays. this chocolate has a melting point of 36 degree C. It’s hard to melt inside our mouth. It taste disgusting anyways. LOL

The point of this chocolate example is that material science wants to understand the relationship between processing, structure, properties, and performances of materials (PSPP relationship). How you make chocolate (process) affects its structure and properties (melting point), which affects its performance (yummy or yucky).

Chemical engineers focus more on the processing while mechanical and civil engineers are more interested in performance. Therefore, Material science engineering tries to bridge these fields of engineering together by analyzing structure and property of materials.

That’s what I learned today: how to make chocolate. LOL

Hello world!

Hello!!!!

The name is William. I decide to start making a new blog. What will this blog be about? It will be about what I’ve learned from my MATS classes at U of M. This blog will have my class notes, professors’ comments, and possibly updates on material science.

So, wish me luck with this blog!