CHEMISTRY COMMUNITY

erica thompson 4I

it all depends on the structure of each molecule. like some have multiple potential bonding sites, but the sites aren’t far enough apart that 2 could bind, and some have 2 bonding sites that are far enough apart that it could bind to 2 molecules at the same time.

erica thompson 4I

I know, hopefully!!

Another error: Ek = mv^2 intead of (1/2) mv^2

erica thompson 4I

Did anyone else notice that the constants sheet we were given for Test 2 was missing equations and had some inaccuracies? Like it says that ΔpΔx≥π instead of (h/4π), and didn't even have the second half of the equations for λ= , En = -, and En = . Was this intentional/did this happen with anyone els...

erica thompson 4I

What strategies can you use to figure out which acids/bases are good for reacting with the tested oxide? I understand that you should try to use the oxide in a reaction as both an acid and a base, but how do you figure out which substances to react the oxide with in the first place?

erica thompson 4I

saigorijavolu33J wrote:Amphoteric compounds are compounds that can react as an acid and base. If you react them with water, there would be 2 reactions. If you write this out then you can tell. Also it is general pattern. There is chart in the textbook which can help.

Where is this chart in the textbook???

erica thompson 4I

What does it mean when there's a delta symbol over the arrow in a chemical equation? As seen in problem 6A.7 b)

erica thompson 4I

The answers to parts a) and b) are H2CO3 (carbonic acid) and H2SO4 (sulfuric acid), respectively. Are we just supposed to know beforehand that carbonic acids and sulfuric acids are common/good ones to know? Are we supposed to memorize acids like these? Or are there strategies you could use to figure...

erica thompson 4I

What strategies can you use to figure out which part of the given salt is the anion/cation you're dealing with? How are you supposed to know that without looking it up?

erica thompson 4I

Ka is the equilibrium constant for a weak acid

erica thompson 4I

I would say don't stress yourself out about exceptions unless they are exceptions he specifically named in class.

erica thompson 4I

I agree, Google is very helpful! That exact coordination compound is also an example in the resource linked below. You could simply count the atoms (although the image given here doesn't seem to include the carbons or hydrogens). https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/Nami...

erica thompson 4I

In lecture Lavelle said that the order is: "(Greek prefix)" + "ligand names in alphabetical order" + "transition metal cation name" + "Roman numeral"

If there are anions, it goes: "anion name" + "(Greek prefix)" + "hydrate"

erica thompson 4I

This is a generalization, but many examples we are given include more than one atom of the same type. Adding onto everyone's answers above, oftentimes the same atom (which therefore has the same electronegativity) can be a good distinguisher of cis- vs. trans-. If the same atom types are on the same...

erica thompson 4I

Always start by thinking of the entire electron configuration first! Much easier than memorizing different VSEPR combinations.

erica thompson 4I

It's helpful to think about how many electron pairs are occupying spots where there may/may not be atoms. Add the Xs and Es together to get the electron configuration, and then subtract as many atoms as there are lone pairs. This way you'll see which molecules should be "bent" down or not.

erica thompson 4I

I always find it's easier to think about it visually! I would recommend drawing the Lewis structures, and more importantly the molecular structures, and drawing arrows toward the molecules with more negative charge. Think about the trajectories of the arrows you're drawing!

erica thompson 4I

Can someone remind me why we remove the atoms that are NOT on the axis first in order to determine molecular shape?

erica thompson 4I

Does anyone know off-hand which problems from 2F are good for practicing just sigma and pi problems for Test 2?

erica thompson 4I

I think hybridization notation is used to describe how many orbitals of each orbital level/type are occupied by electrons when they're not full?

erica thompson 4I

@DHavo_3H I think it has something to do with it being the most stable organization that requires the least amount of energy.

erica thompson 4I

Also electron geometry gives you a hint as to whether certain angles are larger/smaller than expected. If there are more lone pairs, they will have more "push" so the angles will likely be smaller than expected.

erica thompson 4I

Use the VSEPR formula to determine the number of atoms and lone pairs in a molecule. Add up the Xs and the Es to determine the structure of the electrons (e.g. tetrahedral, octahedral, etc.), then remove as many atoms as there are Es to find the actual molecular shape. For example, tetrahedral molec...

erica thompson 4I

As Lavelle stated in lecture, although only atom positions are used to name molecular shapes (e.g. linear), lone pairs still influence the molecular shape. Two examples of lone pairs in linear molecules are the trigonal bipyramidal structure with 3 lone pairs, and the octohedral structure with 4 lon...

erica thompson 4I

The formal energy is the difference between the number of valence electrons an atom normally has, and how many it has in a particular molecule. You can just count each dot individually, and then count only one electron for each bond (line).

erica thompson 4I

I think we have to know how to draw and name the different orbitals in the same layout as the "building up" method.

erica thompson 4I

It's also important to know that electrons don't "jump" from one resonance structure to the other, but rather the different resonance structures show the different placements of electrons as they constantly move about.

erica thompson 4I

Does anyone know if we have to include the nano/giga/mega/etc. prefixes in our answers? Or can we just use the basic unit and multiply it by 10^n in our final answer?

erica thompson 4I

Does carbon prefer to gain or lose 4 electrons in order to form a full shell? Or is it equally as favorable?

erica thompson 4I

How about when it comes to f-orbitals? Problem 2A.5 b) is making me think that having both a half-full/full d-subshell and a full s-subshell is more important than a full f-subshell.

So then is the order of removal for the electrons in the lower periods: p<f<s<d ??

erica thompson 4I

Count from the last full period on the periodic table, representing a full electron shell, and that's how many valence electrons there are!

erica thompson 4I

Depends on the specific molecule and how much "pull" each element has in it.

erica thompson 4I

And bring a pen and a basic calculator! Professor Lavelle said that anything "over $10" is probably not allowed.

erica thompson 4I

It might be useful to do the most up-to-date problems if you're all caught up on the lectures, but I always just do whatever sections I need to focus more on! Just make sure to pace yourself and actually cover every topic :)

erica thompson 4I

A coordinate covalent bond is a covalent bond in which one atom provides both electrons in a pair to another atom.

erica thompson 4I

It would be helpful! In general, metals are the majority of the table on the left side, nonmetals are the upper-right corner, and metalloids sort of form a staircase in between metals and nonmetals.

erica thompson 4I

Everyone above explained the concept that electrons closer to the nucleus have a stronger pull towards it than the further valence electrons nicely. The important thing to take away is that electrons in further shells are more easy to form bonds with other atoms because there's less pull!

erica thompson 4I

I'm not sure I think he said that that's assessed in a formal lab setting? I think talking about the specifics of bond length was more to emphasize that electrons are not bouncing between elements, forming only a few specific double bonds. Electrons are always moving! Can someone elaborate on this? ...

erica thompson 4I

Elements on both sides of the periodic table are essentially trying to get "closer to" a noble gas in terms of stability in its electrons. Because elements on the left side want to lose electrons in order to be more stable, they would have less of an affinity, or attraction to, other elect...

erica thompson 4I

It's also interesting to note that elements with low ionization energies typically form cations, which are typically metals. Because metals are grouped on the left side of the periodic table, you can use this as a memory clue to remind you that the ionization energy increases as you move across a pe...

erica thompson 4I

To respond to DHavo^^, I thought that you could use the two equations in similar ways because you can isolate and substitute v in both?

erica thompson 4I

I thought that the energy levels decreased as you moved further away from the nucleus because there was less electrostatic attraction?

erica thompson 4I

Each orbital can hold a maximum of 2 electrons, and the two electrons in the same orbital have opposite spins.

erica thompson 4I

The reasoning behind the order is that you're supposed to write it in order of lowest energy to highest energy. Because shells that are further away from the nucleus have less electrostatic attraction, further shells have less energy (double-check me on this?).

erica thompson 4I

To add onto Cassidy's comment above, it's important to know that although each orbital can hold a maximum of 2 electrons, each energy shell can have more than 2 (aside from s) because there are multiple orbitals in each shell.

erica thompson 4I

Does the number of energy levels not depend on the number of electrons the atom has? Or was that a simpler way of thinking about it in high school?

erica thompson 4I

Definitely get a lot of sleep! If you are staying up late studying, you are losing sleep and are most likely not really taking in all the information in the later hours anyways. Also remember to sit back and take a deep breath any time you're feeling overwhelmed. Also, most importantly, put it all i...

erica thompson 4I

In response to Brooke above, I think he clarified that it's more about the frequency than the amplitude, as you have to think of each atom separately (like the water flowing example).

erica thompson 4I

Can someone clarify why the Rydberg equation is always negative? Because you're "losing" energy because it's being transferred somewhere else?

erica thompson 4I

Thank you for the advice Ashley! How much do you think you specifically reference this information from this class in your work today, and as a medical student?

erica thompson 4I

You can do problems from the Review sections, as that is the majority of the content for this week's Test.

erica thompson 4I

In the simplest terms, the empirical formula is the relative number of atoms, while the molecular formula is the actual number of atoms.

erica thompson 4I

Like what many people said above, it depends what the problem is asking for. If the problem was asking you to solve for the mass, the answer would be in grams. I believe in lecture today he said that the SI fundamental units were:

- mass = kilograms
- length = meters
- time = seconds

erica thompson 4I

That was definitely a technique he used for that specific problem! Working with stoichiometry problems will never have the same set of moves for each problem. In this case, we had a coefficient with a denominator of 2, so we had to multiply the entire problem by 2 in order to get rid of the fraction...

erica thompson 4I

Responding to Brenna: The question is essentially telling us that we're lining up Ag atoms in a single-file line. You don't have to "convert" the problem to atoms because it is telling you that the unit we're working with is atoms right from the start.

erica thompson 4I

As someone mentioned above, the textbook offers solutions to both the self-tests in the readings and the odd-numbered exercise problems. According to the table of contents, both of them should be in the section at the end of the book with page numbers starting with "C."

Search found 55 matches