CHEMISTRY COMMUNITY

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I think the strength of a conjugate acid/base is relative to the acid/base that it is a conjugate for. So, while the conjugate acid of a weak base is strongER, it doesn't necessarily have to fall under the classification of a strong acid.

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I remember Dr. Lavelle saying during one of the lectures that we won't need to use the equation for any calculations, but it's probably good to know what it is used for and its conceptual basis just in case.

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Does anyone know what information we have to specifically know about these chemotherapy drugs? Is it just that they're an example of a coordination compound? I was absent during this lecture, so I'd appreciate any information! Thank you so much :) I think the main thing we need to know about cispla...

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theoretically, you can do any 5 questions from either section, but I think what most people did was 5 questions from coordination compounds for week 9 and 5 questions from acids and bases for week 10.

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I'm not sure, but for me, my homework grades on MyUCLA are updated and my chemistry community points aren't, so I'm assuming it's at the end of the quarter.

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Like the previous comment said, I don't think the question is asking for the exact pH, but rather, for the relative pH. Meaning, it is asking to analyze whether the salt acts as an acid or a base (or neither), and how it interacts with water/whether or not it produces H3O+ ions.

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CaO is a strong base because it fully dissociates into its constituent components

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A base is a molecule that donates electrons, meaning the molecule will usually have one or more lone electron pairs. In this case, the N in NH3 has a lone electron pair, so it is a base.

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We don't have to memorize all of them, however, I agree that it would be to your benefit to know the most common ones, either the ones given on the table in section 6C.3 in the book, or by just seeing which ones most commonly come up in practice problems.

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A strong acid is one that dissociates into its constituent parts (cation and anion) when dissolved in water

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A ligand is an ion or molecule that bonds to the central metal atom of a coordination compound by donating a pair of electrons to it, meaning that it must have one or more lone pairs of electrons.

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Cisplatin can stop the division of cancer cells, however, it doesn't target cancer cells specifically, so it can potentially stop the division of normal, healthy cells.

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The coordination number represents the amount of bonded sites a central metal atom of a coordination compound has

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Technically, the deadline to switch it was the end of week 7, but I don't think it would hurt to talk to Lavelle about it and see if there's a way around it

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I think either one is fine, since we were taught both

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The lines represent bonds that are to the side or up/down, the shaded triangle symbolizes a bond that is going forward (towards you), and the dashes represent bonds that are going backwards (away from you). However, for the purpose of this class, we don't need to draw them that specifically, we can ...

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I agree that 2.E has a lot of great practice problems, but I am also checking out some worksheets on google and making notecards for each specific molecular geometry that includes: - shape/name - number of electron regions - number of bonded & lone electron pairs - bond angles - VSEPR notation (...

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Trigonal planar would be the general arrangement of the structure, because the central atom has 3 electron regions, however, since only 2/3 of those electron regions are bonded and there is one lone pair, the molecular geometry is a bent shape.

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Theoretically yes, however I think when determining VSEPR model, it is assumed that the formal charge of the lewis structure at hand is already 0, or as close to 0 as it can be.

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I think we need to know the general bond angles and where they are located, however, for example in a bent structure, where the bond angle is <120, we only have to know that it is <120, not the exact angle for each specific structure.

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Double bonds have a stronger attraction because there are more electrons involved in bonding, therefore they are shorter, and triple bonds involve even more electrons and have an ever greater attraction, and are therefore even shorter

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Test 2 is during week 8 (11/18-11/22) and only covers material from after the midterm

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It depends on the electron affinity of the atoms and how many electrons they need to complete their octet. in this case, for example, Cl already has 7 electrons and only needs one more to complete its octet, so adding a double and would violate the octet rule

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Victoria Otuya 4F wrote:I learned an easier way to remember the formal charge equation: valence electron -(dots + line).

does this count "dots" as pairs of dots or individual ones?

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I could be fully wrong here so if I am please someone else correct me: I believe that polarity has to do with the distribution/sharing of electrons, so regardless of which way the structure is "turned" when drawn, if the electrons are distributed equally then it is non polar, and if they a...

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Weakest to strongest in terms of interaction type:
LDF/Van der Waals, dipole-dipole, hydrogen, ionic, covalent

Weakest to strongest in terms of bond type:
single, double, triple

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No, the correct lewis structure would be '

Cl
|
N=O
|
O

with 2 lone pairs on the double bonded oxygen and 3 lone pairs on the single bonded oxygen, so the N doesn't violate the octet rule

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Single bonds are a lot weaker than double bonds because there are less electrons involved in the bonding process. Since they are weaker, they aren't pulled as closely together, whereas double bonds are stronger and pulled closer to each other, and triple bonds even stronger and closer than that

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Hydrogen bonds are the strongest types of bonds because they occur between Hydrogen and the most electronegative elements

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Van Der Waals forces, or London dispersion forces (LDFs), are the weakest form of interactions and are always present in every bond, because all bonds require at least some sort of attraction between atoms/molecules

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Atoms in period 3 (or higher) have d-orbitals in their valence shells that can accommodate additional electrons after the typical limit of 8 valence e- is achieved.

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As a previous concept mentioned, electronegativity trends do not include noble gases. Aside from that, the 4 most electronegative elements (in order) are Fluorine, Oxygen, Nitrogen, and Chlorine; I think these are the only ones that are important to memorize outside of the regular periodic trends.

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The more bonds you have between two atoms, the shorter and stronger your bonds will be. So triple bonds are the shortest and strongest, and single bonds are the longest and weakest. Exact length to be used in calculations will most likely be given in the problem.

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Does it matter whether we use dots or lines to represent the bonds in Lewis structures?

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In lecture, we covered resonance structures and discussed how, if a molecule has multiple resonance structures, the one with formal charges closest to 0 is the most stable. Does that also make it the most accurate structure and therefore the correct answer? In other words, should we just draw out th...

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I had a hard time with this question too, I think we're supposed to use the Rydberg equation, but when I looked at the solutions guide I didn't fully understand it either, so other than that I don't know much, sorry!

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So as mentioned in the previous comments, those are noble gases that are unreactive and have full valence electron shells. Essentially, think of it as substituting a variable for the configuration up until that element, the same way we substitute h for Planck's constant and c for the speed of light.

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I'm not sure whether or not it matters if you include it, because it means the same thing either way, but the x, y, and z only exists for p-orbitals.

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So I know for electron configurations you can write out the p-orbital configurations as, for example, either (p3) or (px1)(py1)(pz1); but which one are we supposed to use/which one is more correct/accurate?

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I was trying to work through this problem with a friend and we couldn't figure it out so we looked at the solution guide, and for the most part it's understandable, except I can't figure out for the (1/n^2) equation how they got 3.29 x 10^15 s^-1 as the denominator?

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Bouncing off of the previous comment, electrons exhibit wavelike properties, which is what keeps them moving even when they lose energy, therefore preventing them from falling all the way down to the nucleus.

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There is a limit to the accuracy to which both momentum and position are known. In simple terms: it is extremely difficult to pinpoint the exact location of such a minuscule particle while it is moving. Inversely, it is not possible to know the momentum of that particle if it is stopped or slowed to...

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During lecture on Friday, Professor Lavelle mentioned that orbitals are actually represented as wave functions and are therefore mathematical functions. Can someone clarify what that means, both theoretically and practically?

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As the previous comments mentioned, any wavelength smaller than 10^-15 m is undetectable and would only show particle-like properties. The most important thing to remember is that the wavelength produced by the equation is directly influenced by the mass of the object in question. The larger the mas...

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A black body is a hypothetical concept because if such a thing were truly to exist, it would absorb and emit all electromagnetic radiation and therefore all visible light, making it invisible to the human eye. A good way to imagine it is as a smaller version of a black hole, as mentioned in the prev...

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In conversions from moles to mass, we only use molar mass, and the given number of moles and mass, so when do we use Avogadro's number?

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I'm not sure how everyone else's high school chemistry experience was, but my teacher didn't really cover the material in depth, so I was wondering - is there any other/more efficient strategy to balance chemical equations other than trial and error? And if not, is there at least a strategic startin...

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I understand the difference between empirical and molecular formulas, but what is the purpose of simplifying molecular formulas to empirical formulas? Because once you change the amounts/numbers of the individual elements, doesn't it change what compound it is? And if so, then what is the use of it/...

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Also one thing to keep in mind is that most graphing calculators have a sig fig function if you're using those for homework problems, but we're not allowed to use those on exams, so it's probably better to just get in the habit of keeping more sig figs throughout the problem and then rounding at the...

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I was reading through the posts on this board but I thought I'd post myself just to clarify - does the number of sig figs you give in your solution have to match the number of sig figs that the given values in the problem have?

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