Chemistry of Computers

Hopewell Valley Student Podcasting Network

Chemistry Connections

Chemistry of Computers

Episode #11  

Welcome to Chemistry Connections, my name is Alex and Tom and we are your hosts for episode 11 called The Chemistry of Computers. Today we will be discussing how chemistry is essential for the function of computers .

Segment 1: Introduction to Chemistry of Laptops 

Computers are heavily present in our society today, they are used in almost all jobs, schools, etc. Our world relies on computers and computers rely on chemistry. 

There are several parts of the computer that are necessary for its function, first of which is the motherboard, this is like the nervous system of the computer and it allows all of the different components to communicate with each other. 

• Central Processing unit or CPU, this is a silicon chip that acts as the brain of the computer, it processes all the data for the computer. 
• These days most computers store information in a device called a Solid State Drive or SSD, this device holds all the information for the computer. 
• Alongside these more behind the scenes aspects are the more well known parts of a computer such as the screen or battery.

All of these components use electricity and generate heat, so in order to prevent the computer from getting too hot, they need to be cooled, most commonly by fans. 

Segment 2: The Chemistry Behind Computers

Conductors and Semiconductors: 

• There are several materials that are essential for the function of a computer, some of the materials include silicon, plastic, fiberglass, copper and gold, lithium 
• These materials are sorted into three categories: Conductors, Semiconductors, and insulators
• Conductors are what allow electricity to flow because electrons can transfer from particle to particle 
• When electricity passes through a conductor it faces little resistance, allowing for uncontrolled free flowing current. 
•  The insulator does not allow electrical current to travel through it since it has high resistance levels. 
• Semiconductors are a combination of the two, where they allow for the flow of electricity to be controlled. This is done by providing a slightly resistant material.  
• Almost all computers this is through silicon chips, however pure silicon is typically an insulator. This is because pure silicon is constructed from atoms that contain 4 electrons in the orbital furthest from the atom’s nucleus. 
• Due to this atomic structure, the silicon atoms covalently bond together to form a crystalline lattice. By themselves this lattice does not conduct electricity, since the electrons are held stable in the rigid structure. In order for silicon to become a semiconductor electrons must be added or subtracted from the silicon lattice. 
• This process starts with materials that either have three or five electrons that are mixed into the silicon to disrupt the covalent bonds in the crystal lattice structure, this process is called doping. N-type doping uses materials with 5 electrons in the outer orbital, the most common materials used for this are phosphorus and arsenic. These materials add a fifth free electron to the lattice which allows the material to conduct electricity since the electrons are now free flowing. 
• P-type doping is the same process just with materials that have three electrons in their outer ring, such as boron or gallium. The addition of an atom like this leaves the absence of an electron or a hole through which the free-flowing electron can travel. 
• N and P type semiconductors are used to create transistors, these small devices are essential for computers. 
• Transistors act as both an electrical switch as well as an amplifier. They can also be used to retain code as memory blocks, making them crucial to microchip manufacturing, from processors to memory cards. 

Light and Screens: 

• Utilizes liquid crystal molecules
• Liquid Crystal molecules are molecules that exist in a state between liquids and solids because they flow like a liquid but still retain the crystal-like arrangements of a solid.
• Rod-like molecular structure
• Strong Dipole-Dipole bonds 
• Generally have the same orientation, meaning the molecules point the same way, but they aren’t quite as rigidly organized in a lattice structure like solids. They also have much more of an intrinsic order than liquids.
• Essentially, an LED will emit unpolarized light waves that travel in random directions with various orientations. A polarizing filter will only allow light waves with a certain orientation to pass through in order to bring order to polarize the light, meaning to organize them. Another polarizing filter will then be placed on top of the original filter, but turned 90 degrees so that the light waves that have already been polarized will be at the orientation of the first filter, and won’t be able to go through the second. However, Liquid Crystal molecules have an interesting property in which they twist light waves. This means that when these molecules are placed in between the two polarizing filters, they can twist the polarized waves from the first filter to go through the second filter, showing the light waves to whoever is watching. Also, the specific type of Liquid Crystal Molecules used in screens have a positive charge on one end, meaning that an electric field can be applied to the molecule which would disturb its structure and prevent it from twisting the light waves, once again preventing light from passing through the second filter. Based on where light should be shown on the screen, an electric field will be applied to certain areas of LCMs, controlling whether or not light can pass. This process is done in a very small area known as a pixel, and the process is done over the whole screen to have different areas of the screen with light showing and areas where it isn’t.

Batteries:

• Pretty much all laptops these days used lithium ion batteries because the are rechargeable and light
• A battery is made up of an anode, cathode, separator, electrolyte, and two current collectors (positive and negative). 
• The anode and cathode store the lithium. The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa through the separator. The movement of the lithium ions creates free electrons in the anode which creates a charge at the positive current collector. The electrical current then flows from the current collector through a device being powered (cell phone, computer, etc.) to the negative current collector. The separator blocks the flow of electrons inside the battery.
• While the battery is discharging and providing an electric current, the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other. When plugging in the device, the opposite happens: Lithium ions are released by the cathode and received by the anode

Cooling: 

• All computers require electricity to function, and some computer components require more electricity than others. As electricity passes across circuits and through wires, it meets a natural degree of resistance. The stronger and more powerful the part is the heat it generates This heat creates the necessity for cooling. 
• There are two main types of cooling in computers, air cooling and water cooling. Water cooling is more efficient than air cooling due to water’s high specific heat or large heat capacity. This means that it takes a lot of energy to change the temperature of water. This chemical property makes it ideal for cooling computer components. 

Segment 3: Personal Connections

What interested you in this topic? Why is it important? Anything else you’d like to share.

• Speaking of cooling, do you remember when we were struggling to install the fans in the computer we built?
• This is important because computers are all around us and are essential to life nowadays
• Tom and I find this topic interesting because we both built computers.

Thank you for listening to this episode of Chemistry Connections. For more student-run podcasts and digital content, make sure that you visit www.hvspn.com. 

Sources:

https://phys.org/news/2022-02-chemistry-lcd-flat-screen-devices-scientist.html

https://www.britannica.com/science/liquid-crystal/Liquid-crystal-compounds

https://www.edisongroup.com/edison-explains/semiconductors/22298/ 

https://uh.edu/~chembi/liquidcrystals.pdf

http://www.bigshotcamera.com/learn/lcd-display/liquid-crystal

https://www.energy.gov/eere/articles/how-does-lithium-ion-battery-work 

Music Credits

Warm Nights by @LakeyInspired 

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