CHEMISTRY COMMUNITY

Ashley Kim 3F

Some molecules may be Lewis acids but not Bronsted acids because they have the ability to accept a lone pair of electrons, but do not have a proton to donate.

Ashley Kim 3F

Ka is the strength of an acid - a high Ka value means that the acid is strong, while a low Ka value indicates a weak acid. pKa is inverse - a high pKa value means that the acid is weak, while a low pKa value means that the acid is strong. pH is -log[H3O+] and is a measure of the concentration of hyd...

Ashley Kim 3F

The 2 is just to indicate the period that oxygen is found in and is not completely necessary when writing the hybridization. However, it can't hurt to put it on your answer !

Ashley Kim 3F

I think that as it gets closer to the final, it is best to review the topics that you know you are weakest at and really try to understand the concepts at play.

Ashley Kim 3F

We can tell based off of the definition of a Lewis acid, which is a compound that can accept an electron pair, or a Lewis base, which is a compound that can donate an electron pair.

Ashley Kim 3F

The difference between Bronsted and Lewis acids and bases is in the way that they describe the actions of an acid and base. The Bronsted definition has to do with proton transfer while the Lewis definition has to do with electron lone pairs.

Ashley Kim 3F

For the final, I would recommend looking over key concepts and making sure that you fully understand them, and then solve practice problems. Since we have taken two tests and a midterm, we know what types of problems will be asked and should prepare accordingly.

Ashley Kim 3F

Main group elements have pretty consistent oxidation numbers, so they can be easily memorized. As for transition metals, I think that the best option would be to practice and memorize the oxidation numbers of the most common ones.

Ashley Kim 3F

There is a difference between an amine and an ammine, and it's important to differentiate. An amine is a functional group from ammonia, while an ammine refers to a group of coordination compounds where ammonia is a ligand.

Ashley Kim 3F

The difference is by definition, as Bronsted acids and bases are in terms of proton transfer while Lewis acids and bases are in terms of electron pairs.

Ashley Kim 3F

I think a lot of the prefixes can be easily memorized by using the root! And for the other components of naming, you should practice and memorize the rules too.

Ashley Kim 3F

There is a greater overlap between atomic orbitals in sigma bonds, meaning that it is more likely that more electrons are present in overlap.

Ashley Kim 3F

I don't think it necessarily matters how the formula is arranged as long as the naming is done alphabetically.

Ashley Kim 3F

It can't hurt to always use the correct amount of sig figs when indicating answers on an exam!

Ashley Kim 3F

Lone pairs on the central atom account for the electronic arrangement of a molecule and sometimes for the shape of the molecule.

Ashley Kim 3F

Induced dipoles occur when temporary and fluctuating electron densities create a net favorable attractive force. Dipole-induced dipoles usually occur between a polar and nonpolar molecule.

Ashley Kim 3F

is writing "less than 109.5" an exceptable answer, or do we have to give a specific number? I'm pretty sure than writing "less than 109.5" is an acceptable answer since we haven't gone much further than that in terms of bond angles. As of now, we don't know how to calculate the ...

Ashley Kim 3F

Electron configurations, unless otherwise specified, refer to the ground-state electron configuration of lowest energy. If the electrons were excited, it would specify in the problem.

Ashley Kim 3F

I'm reading over the textbook sections relevant to the topics tested on the midterm to get a grasp of the conceptual ideas, and then I'm going to do the homework problems. Looking over lecture notes and solving problems is probably the way to go!

Ashley Kim 3F

I agree with the above posts - as you practice VSEPR related problems and get more exposure to relationships between the shapes and angles, I am sure that you will find yourself having memorized the corresponding angles!

Ashley Kim 3F

Based on the midterm, I would review and practice concepts that I am less confident in to reinforce those topics, and as for material that was covered after the midterm, I would make sure that I can fully grasp the conceptual base of the topic and can apply it to practice problems.

Ashley Kim 3F

As everyone above mentioned, the only two possible values for ms are +½ and -½. In a quiz or test, the spin of the electron will most likely be easy to determine given the wording or information provided in the question, so I don't think you need to worry about it too much!

Ashley Kim 3F

Hydrogen bonding is prevalent in biological systems because of its strength despite the noncovalent interaction it has in many organic molecules. As the comment above mentions, it helps stabilize biological systems!

Ashley Kim 3F

De Broglie's equation essentially calculates the wavelength using a particle's mass and velocity, so given any one of those values (knowing that the particle has mass), you should use the De Broglie equation to solve for the unknown value.

Ashley Kim 3F

Elements with orbitals in the d-block can have expanded octets. However, although P, S, and Cl do not have orbitals in the d-block, they are exceptions to the octet rule and can also hold more electrons than the standard octet.

Ashley Kim 3F

Dissociation energy is always positive because you are inputting energy into the system, not taking it out.

Ashley Kim 3F

You would remove electrons from the 4s orbital because it is of higher energy than the 3d orbital.

Ashley Kim 3F

I don't recall going over how to calculate bond length during class, so I'm pretty sure we don't need to know how to do that for the midterm.

Ashley Kim 3F

Usually, the elements at either end of the periodic table, when bonded together, form ionic bonds because it is easier for the electrons to be transferred due to the number of valence electrons they have. On the other hand, covalent bonds form between elements that cannot transfer electrons but inst...

Ashley Kim 3F

I think that to be safe, we should understand the concept of a resonance hybrid and how to draw one, just in case a question comes up on the midterm. But I wouldn't stress about it too much!

Ashley Kim 3F

Although the first method of writing the electron configuration is not wrong, I think that Dr. Lavelle mentioned that he would like for us to notate it the second way, unlike how we did in high school.

Ashley Kim 3F

It is always more difficult to remove the second electron because the net positive charge exerted by the nucleus affects it greater than the electrons in the outer shells. As you remove more electrons, the more energy it takes to remove each one.

Ashley Kim 3F

I agree with all the statements made above - ionic bonds occur between a nonmetal and a metal and the valence electrons are transferred between the two atoms. On the other hand, covalent bonds occur when two nonmetal atoms share electrons pairs.

Ashley Kim 3F

A compound with resonance is stable than one that does not have resonance because it is a hybrid of individual resonance structures and does not shift between them.

Ashley Kim 3F

I am pretty sure that these values are on the equation sheet because they are not particularly nice numbers to memorize!

Ashley Kim 3F

Unless Dr. Lavelle states so, I do not think that there will be an official practice midterm posted. However, the test bank is a useful resource to see what types of problems will be on the homework. I also think that the types of questions we see on the homework should be indicative of the types of...

Ashley Kim 3F

I think that it does matter which orbital you put the 4th arrow in to indicate to the grader that you understand the concept of orbitals. One orbital must be filled before the next can be filled (this being after there is one arrow in each orbital), so it would make sense to put the 4th arrow in the...

Ashley Kim 3F

Some study tips that I find useful are to first thoroughly understand the conceptual aspects of the topics we cover in class, and then do practice problems to reinforce the application of those concepts. Because the practice problems that we have seen assigned on the homework so far are mostly calcu...

Ashley Kim 3F

I know that in high school, we never wrote the x, y, z, in the electron configurations, but I think I remember that during lecture on Friday, Dr. Lavelle mentioned that he wouldn't mind if we wrote out the x, y, z to show that we understand the meaning of it.

Ashley Kim 3F

Yes, I believe that if there is a greater energy difference (eg. difference between energy levels increases), the transition between energy levels is larger, meaning that more energy is absorbed or emitted. Therefore, since the photon that is emitted has the same energy as the energy difference, it ...

Ashley Kim 3F

I would think so, so maybe we assume that the situations described in problems involving the speed of light occur in a vacuum?

Ashley Kim 3F

To find the final concentration of potassium ions and sulfide ions, you have to use stoichiometry to find the total moles of K+ and S2- ions. Add the number of moles of K+ ions in .500g KCl, K2S, and K3PO4, respectively and divide the total moles K+ by .5L H2O to get the final concentration of potas...

Ashley Kim 3F

The number of sig figs depends on the lowest sig fig of the numbers give in the problem. However, if the problem does not mention any numbers that you can base your sig figs on, I think it's safe to have at least 4 sig figs.

Ashley Kim 3F

Dr. Lavelle mentioned that the emission and absorption must be balanced, so the amount of energy that is emitted is equal to the amount of energy that is absorbed.

Ashley Kim 3F

When an electron drops two levels, it is not that two photons are emitted, but that the one photon that is emitted has more energy that if the electron only dropped one level.

Ashley Kim 3F

I remember my TA telling us that it is not completely necessary to be able to name all the compounds and oxides and such, but that knowing the most common few is recommended and will be beneficial.

Ashley Kim 3F

In conjunction with what everyone else said, in this situation, there is no limiting reactant. A practical way to think about this is in terms of baking - if the recipe calls for a certain amount of an ingredient and you have the ingredients in the required amounts, you will be able to create the ba...

Ashley Kim 3F

In regards to the post right above me, I think that the safest bet is to use the convention that we probably learned in high school to not round until you get to the final answer. At that point, we should take into account the smallest number of sig figs in the given problem and round accordingly. T...

Ashley Kim 3F

I agree that there are multiple ways to go about chemistry problems, but from my experience, what the limiting reactant is is clearer when you are comparing moles. Only looking at the given masses of molecules will not always tell you the limiting reactant because you need to take into account the m...

Ashley Kim 3F

I think that imagining that you have 100g of a molecule when figuring out empirical and molecular formulas is just a useful tip for when the numbers are not particularly pretty or easy to work with, but not a necessary component. However, you can not go directly to moles from the given grams of diff...

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