Elements and Properties
Biochemistry is probably the most basic level of knowledge for biology - everything is built on these principles. You'll learn about basic elements, properties, and more. This lesson specifically is essentially a short recap of chemistry. Let's dive in!
First off, we'll start with what counts as organic. Organic molecules or compounds are carbon-based, meaning they have a carbon within their structure. They also usually contain hydrogen, oxygen, or nitrogen. Anything that doesn't contain a carbon, like water (H2O), is not organic. Interestingly, carbon dioxide isn't considered to be organic, so there are exceptions to this rule, but generally, if it has a carbon, it's organic. Carbon's unique property of having only 4 valence electrons allows it to bond particularly well, which we'll see later in saturated polymers.
Next, we have the properties of water. Water has:
- Cohesion: water bonding to other water molecules (same species - same species). Caused by hydrogen bonds.
- Adhesion: water molecules bonding to other molecules (one species - another species). Caused by hydrogen bonds between H2O and other substances.
- Heat of Vaporization: amount of heat required to convert 1 gram of a liquid into a gaseous state (water requires a high amount of energy for 1 gram of water to be converted into gas, so it has a High Heat of Vaporization)
- Specific Heat: amount of energy it takes to change the temperature (water requires a lot of energy to do so, so it has a High Specific Heat).
- Universal Solvent: water is a universal solvent because of its polarity (it's polar). This means it can dissolve compounds with weak, ionic bonds.
- Density: Ice is less dense than water, which is why is floats on top of water instead of sinking to the bottom. This way, the water below the ice is insulated and doesn't change its temperature much, allowing creatures like fish in water to survive during winter.
Something that is hydrophilic means it is attracted to water (polar molecules), while something that is hydrophobic is not attracted to water (nonpolar molecules). Hydrophilic substances include salts and ions, while hydrophobic substances include fats and oils. If you've ever tried to mix oil and water together, you'll have realized that they don't mix and will always stay separate. This is due to the hydrophobic properties of oil.
Additionally, water is a good buffer. This means that it is a molecule that controls pH levels, because it's neutral. It can donate H+ when a solution is too basic, and OH- when a solution is too acidic.
That's it for elements! Next up is monomers and polymers (it'll have pictures :D ).
Thank you for this resource.
ReplyDeleteWhat would an example of adhesion?
ReplyDeleteAn example of adhesion would be water sticking to another object, such as water droplets sticking to the leaves of a plant. Hope that helps!! :)
Deletehow can you tell something is polar?
ReplyDeleteI like to go by the acronym SNAP - Symmetric Nonpolar, Asymmetric Polar. When looking at a molecule look for 2 axes of symmetry. Imagine an X and Y axis with the origin at the middle of the molecule. If the molecule is symmetric across both the X and Y axis, it is nonpolar (Symmetric = Nonpolar). If neither or only side is symmetrical then it is polar (Asymmetric = Polar). Take methane for example. Methane is CH4, so it looks like this:
DeleteH
H C H
H
It is symmetric across the horizontal and vertical axes, so it is nonpolar.
Note that since the atoms are symmetric, that means there is also a symmetric distribution of charge. If you were to take the electronegative difference of the C and H, it would amount to 0. If you get a difference of 0, it is nonpolar. If you get any number higher than 0, it is polar.
Hope that helps!
Ah looks like the formatting of the methane is off; just google methane structure and you'll see it clearly.
Deletei dont remember learning that in chemistry.
ReplyDeleteThis should be part of a basic high school chemistry curriculum. If you're learning chemistry in middle school, you may not learn it. I recommend checking out Khan Academy, they have great resources!
DeleteDoes the water turn into just a hydrogen atom when it donates OH-? Doesn't that make it more acidic since there's now a H and an OH?
ReplyDeleteWhen water donates an OH-, it does not do it alone. The full balanced equation for this reaction is:
Delete2H2O <-> H3O + OH-
When the 2 water molecules collectively donate an OH-, the leftover H will join with the other water molecule to form H3O. This solution right now is neutral, but an increase in H3Owill turn it more acidic. Hope that helps!