Hello everybody! Today we are going to be writing about biology! If you don’t understand our summaries, feel free to ask us questions or to send us some feedback! It also helps to watch the videos as well. I hope you enjoy it!
Biology is a type of research that is focused on living organisms. It is divided in different fields to focus somewhat specifically on an organism's structure, physical processes, chemical processes, behaviour, history, and its separate classification that differentiates itself from other living beings.
We are going to have to know a little chemistry before we are going to get anything about biology. Everything is made up of organic molecules.
An organic compound is one type of many compounds. In order for a compound to be an organic compound, it needs to contain carbon.
Carbon is an element on the periodic table. It is especially special because it is usually bonded with many other elements. Carbon is a pretty small atom. It has six protons and neutrons, which means, it has an atom weight of twelve, which we get by adding the amount of protons and neutrons. Since it is so small, it doesn’t take up too much space.
Carbon is also very flexible and can get into double and triple bonds. And it can shape itself into many different things that would only be able to be accomplished by small atoms such as carbon.
There is a saying that says that carbon is kind. The reason why is because, unlike some other atoms, is not desperate to fill their electron orbitals. It is perfectly fine not having the desired amount. And instead of ripping electrons from other substances, it usually just bonds with other atoms to fulfill their orbitals.
And since carbon wants four more electrons, it will most likely bond with whatever is in close proximity. This means that carbon will bond with up to four other things at the same time.
Also, carbon is not picky about any of this, it would be perfectly happy bonding with any other molecules.
Carbon can bond in infinite configurations with an astounding variety of atoms. This makes carbon the core atom of creating living structures because of this. Without carbon, we might not be alive!
In short, carbon is the foundation of biology.
The reason why carbon bonds with all these atoms is because carbon needs six electrons in order to be a stable element.
Carbon shares a type of bond called covalent. This means that atoms are sharing electrons with each other.
Gilbert Louis is a man who created the Lewis Dot Structures, but also made the Lewis Acids and Bases. He was nominated for the Nobel Prize 35 times.
More than anyone else in history. Lewis was the one who made the term photon. And he was the first to have thought of covalent bonds. Some people believe he might have been the most influential chemist of all time.
The reason why Gilbert Lewis is so important for our case is the Lewis Dot Structure he created. It didn't always exist, so when Lewis created it was so useful we still use it today.
Here is how the Lewis Dot Structure works. It basically shows how atoms bond together to make molecules. The elements we are working with will end up reacting to have all the atoms end up with eight electrons in its outer shell. This rule is called the octet rule.
Since all atoms want to have eight electrons, all the atoms end up happy. This octet rule shows us why all these covalent bonds bond with each other. An example is CO2 which has carbon that starts with six electrons so it bonds with oxygen to complete its octet.
There are many different variations of atoms connecting with more and atoms trying to fulfill their octets. These variations are extremely complex and can stretch very far to create many different substances. Although we could help you memorize all of these, we think of it more important to get the concept of things.
One thing that is interesting about water is that it is a polar covalent bond. This means that one side of it is positively charged, and one side is negatively charged. When you pour too much water into a cup, the water kind of clings to each other and makes a little dome of water before overflowing.
Another type of bond is an Ionic Bond. Unlike covalent bonds, ionic bonds don’t share electrons but give them away. The most common Ionic bond today is salt. The reason why is that one of the elements has one extra electron in its octet, and one has one short of an electron. If one of them donates their extra electron, they become so charged, that they immediately stick together forming salt.
Lastly, the hydrogen bond. Water is a good example. Since it is a polar covalent bond, the hydrogen side is positively charged, and the oxygen side is negatively charged. So water molecules stick together hydrogen to the oxygen side. This is an example of a hydrogen bond.
One last thing to keep in mind is that all types of bonds are different strengths. So, even if two bonds are both covalent bonds, they can be different strengths.
Water is the only substance that occurs in solid, liquid, and gas forms completely naturally. All life is dependent on there being water around. Us humans are looking out on other planets to see if there is water. But, why is all life so dependent on water?
Water is made up of two hydrogen atoms and one oxygen. They each share one electron each. This bond is called a covalent bond.
The special thing about water is that it also has a hydrogen bond that makes the bond a polar covalent bond. That means the hydrogen atoms are positively charged and the oxygen atoms are negatively charged!
The hydrogen bond that appears in water is extremely important. Water has a high cohesion which means that it is attracted to something of the like substance. This also means that water is attracted to water. Water has the highest amount of cohesion than any other non-metallic liquid.
This allows some species of animals to walk on water.
Water also does have adhesive forces. This means that a substance is attracted to another substance. An example of this is glass. Instead of beading up when exposed to it, the water actually spreads out. When this happens, the cohesive forces are weaker than the adhesive forces.
Another very cool thing that water can do, is it can defy gravity. This is called Capillary Action when water defies gravity due to adhesive forces.
Since water is a polar molecule, it is also extremely good at dissolving things. That is why water is considered as the “universal solvent.” In case you didn’t know, a solvent is what a certain substance is being dissolved in.
Some substances such as sugar and salt have such polarity that they can actually break the cohesive forces of the water. And the water actually bonds around the atoms with extreme polarity.
When a molecule cannot penetrate the cohesive forces of water, we get a hydrophobic substance. These molecules aren’t able to mix with water. An example is oil. And when put into water, the cohesive forces push the substance out of itself.
In history there was a man named Henry Cavendish. He is most famous for recognizing hydrogen gas as a single substance. Also, for finding out the composition of water. Back then, people believed that water was an element itself. Henry Cavendish, however, saw that water was actually made up of oxygen and hydrogen. Only until after Cavendish’s death did we find out that he prediscovered many laws found over the course of history.
When ice is dropped into water, it floats. It isn’t extremely surprising, but it actually is. Everything else on earth is more dense and heavy when in a solid form. The reason why it is this way is that at 32 degrees fahrenheit or 0 degrees celsius water starts to freeze. When this happens, the atoms that make up water start to spread apart, therefore making ice less dense.
But because of water's special characteristics that ice floats, is one reason why life on earth is possible. If ice wasn’t less dense, the oceans would be completely frozen because when it starts to freeze, it would freeze and then sink over and over until the ocean was a giant popsicle.
Another important quality of water is its high heat capacity, which means that water is extremely good at holding heat. This is also good because it is very hard to heat and cool the oceans. That means, the oceans can hold a lot of heat keeping our planet cool.
This is also why you sweat. Your sweat holds a lot of heat and then escapes your body taking the heat with it. Without water, you wouldn’t be able to sweat, and therefore would be very vulnerable to heat stroke.
Thank you for reading about biology! Always a pleasure. Please come back for more summaries on many more fascinating subjects. We are always open to feedback, so feel free to share any information you think would be helpful to know! See you next time!