CHEMISTRY COMMUNITY

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I am not sure why this statement is true KA1>KA2>KA3. Please explain why it is harder to lose H+ from negatively charged ions.

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The two specifies what row the element is in, so since carbon is in the second row it has the 2 in front of the p. Unless specified, sp^2 can still be the correct hybridization for carbon.

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They are both chelating ligands because they are complexes that contain a ligand that forms a ring of atoms around a central atom. The ring is formed because 2 electron pairs are donated for bidentate ligands. Polydentate ligands just have to donate more than one electron pair.

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How is oxidation state determined? Please explain this step by step using the heme complex from the practice final problems (Marshmallow) #21, which tells you to find the oxidation state of Iron. Feel free to explain this using other examples as well.

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I am rereading the notes from week 10, lecture 1 and I see if the pH<pKA then the solution is acidic. Is this true all the time because in the example for HA from lecture, the pH is more than pKA since the pH is 6 and the pKA is 4.22, the solution is still labeled as acidic? How is this true?

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How is coordination number determined?
Can someone explain this using the following example: [Fe(CN)6]^4-

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For many examples I am noticing that the hybridization of Carbon begins with 2s instead of just s. For instance, methyl-2-cyanoacrylate has carbons that have C2sp^2 as their hybridization. Can someone explain why it is 2s instead of just s?

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Is a Bronsted base and acid determined only on whether or not a proton is accepted or donated?

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Why does the reaction between an acid and a base product salt and water?

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Should I only consider lewis structures and orbitals when determining hybridization?

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I would also look at what elements makeup the compound, since the location of the element on the periodic table could provide insight on whether or not the compound is acidic, basic, or both.

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I would review outline 5 on the class website, it details what we need to know regarding coordination compounds, etc.

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I would also remember to consider that just because molecules have the same AXE, it does not mean they will have the same angles.

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What is the best way to understand polarity and apply it to molecules? Are there any rules I should memorize to be able to identify if the molecule I am looking at is polar or nonpolar? Are there any exceptions to general rules of polarity?

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How do radicals contribute to molecular shape? Do they cause major repulsion?

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I base the sigma and pi bonds off of how many bonds are present:
1 bond= sigma
double bound= sigma + pi
triple bond= sigma +2 pi bond

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Is hybridization mainly depending on orbitals and the space electrons occupy?

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I think the solutions manual shows the shape and then the shape including all of the electronic densities ( which includes lone pairs). Be sure to read the question carefully and see whether or not the lone pairs should be accounted for when identifying the shape.

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There is not going to be quantum or fundamentals on the exam. It will be the material starting with types of bonds ( eg. London Dispersion) all the way until Monday's lecture on hybridization (Pi and Sigma Bonds).

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This is why you may see lone pairs on opposite sides of each other because lone pairs want to be far from each other due to their repulsion. Thus, you may see them on opposite sides of the equatorial axis of a molecule.

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I would review the concept of repulsion Lavelle talked about in class. He lays out the parts of a molecule that cause repulsion. For instance, a lone pair causes repulsion and can cause two atoms to come closer together. This would decrease the angle between the atoms.

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T shaped is mentioned in the homework problems for 2E, so I recommend doing those problems and referring to the chart Julia Chang posted which shows how lone pairs can influence the shape. In this case, T shape is created when there are two lone pairs.

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In case I forgot how to do a conversion, I use the equation sheet and confirm my answer using KHDUDCM ( King Henry Doesn't Usually Drink Chocolate Milk). This acronym stands for each unit and u is the base unit you convert to a different unit, the number of times you move from U or another base unit...

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The midterm did say to draw the resonance structure if appropriate, so I think in the future you would have to determine whether or not there is a resonance structure. For instance, if it doesn't matter which oxygen has the double bond and which one has the single bond it may look like you have a re...

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Try to draw the lewis structure where it will be the most stable unless the questions asks you otherwise or to match the charge on the molecule given in the question. Ultimately, make sure you are addressing the question.

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I just realized you would need to calculate velocity by manipulating the equations.

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What is our velocity for our kinetic energy?

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Here is the question: " If 10.00 g of glucose (C6H12O6) is initially present and 5.00 g of H20 is formed, how much grams of glucose is left over? How many moles of 02 were initially present? (glucose is 180.156 g/mol) I converted water and glucose into moles first, but then I got stuck. What ne...

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This is a typo: On the website you can find the typo and the correction: "1B.27
Solution manual states Δv = 5.0 m.s-1
Velocity was given as 5.00 ± 5.0 m.s-1
Therefore Δv = 10.0 m.s-1
With the correction, the final answer is: Δx = 6.7 x 10-37 m"

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I believe he was just referring to the the characteristics of a bond being covalent in relation to its partial ionic character and propensity to attract electrons. He did then talk about how bonds could have both ionic and covalent characteristics, where the electronegativity difference determines w...

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Does Cl04- not have any resonance structures? I thought it did have resonance, but it makes more sense to me that oxygen has the negative charge because it's more electronegative.

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The way I convert from moles to atoms is I take avogadro's number and I multiply by the molar amount given/ found, since avogadro's number is equal to one mole. Thus, to convert from atoms to moles you would do the opposite, which is to divide.

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I would study that information, I think it would be helpful to know what color has a higher frequency than the other because we did a practice problem in a step-up session that asked to identify the color the frequency we calculated matched.

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In this case I would just count the number of valence electrons for each element and add them like we did in class on Wednesday. There would be no need to subtract or add electrons unless specified.

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Draw the Lewis structure of (d) BrF3

Why does Br have two extra lone pairs at the top? Is it one of the exceptions to the octet rule?

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Draw the Lewis structure of (c) SiO2

Why does the lewis structure have double bonds in between Si and Oxygen instead of just single bonds with lone pairs around the oxygen?

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Formal charge can also help you determine whether or not a certain lewis structure is better than the other if there is more than one way to draw a lewis structure. The more stable the formal charge is, the better the lewis structure is.

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I think the midterm will cover everything we have learned in class, but it will most likely focus more on the units we studied after the fundamentals since we were already tested on high school chem

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1A.15 states "Arrange the following types of photons of electromagnetic radiation in order of increasing energy: γ-rays, visible light, ultraviolet radiation, microwaves, x-rays." Would I just have to memorize the properties of each type of photons? How else could I solve this problem with...

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He did mention in class that you will not need to know how to draw orbitals, but he said it helps to get a general idea of how the orbitals look to clarify certain features of the orbitals. For instance, the principal and orbital angular momentum quantum numbers. If you are a more visual learner, I ...

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I highly highly recommend going to the Step Up sessions. I feel like they review the material in class really well, so if I am lost I can just ask any questions during the review. They also provide some practice problems for extra support. I think this is a great way to refresh topics and see what t...

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1D.15 states "What are the principal and orbital angular momentum quantum numbers for each of the following orbitals: (a) 6p; (b) 3d; (c) 2p; (d) 5f? I understand that the principal number is just the number given, but can someone explain how to find the orbital angular momentum number?

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In class we discussed the example of px,py,pz in relation to electrons. Does x,y,z represent the coordinate plane? Can someone explain the role of x,y,z?

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Does anyone know if the energy levels correspond to the electron shells of a particular atom?

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The periodic table is not color coded on tests. I recommend using the periodic table from the chem 14 A website when doing your homework. This will help you become more accustomed to using the same periodic table that is used on tests and will make taking the tests seem more familiar.

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During one of the step up sessions, the UA said to use M1V1=M2V2 whenever a dilution is mentioned. However, when you can't identify a dilution is occurring you most likely have to use M= m/v. This may not always be the case, but this is how I would think of it in simplest terms.

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I recommend rounding to the correct number of sig figs at the end for your answer, but during your work I suggest not rounding to the correct number of sig figs. This aids in reducing any rounding error in the end. Also, be sure your answer in sig figs matches the smallest sig fig provided in the qu...

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I also heard that formulas can be formatted with C and H first and then every other element after is placed alphabetically. Is this the hill system? Does this always work?

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When told to find the empirical or molecular formula, how do I know what order to put the elements in? Is there a specific order or rules I should follow?

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Self Test E.1B states, "A double espresso contains 3.14 mol H2O. What is the number of H atoms present in the espresso?" Based on the result, I was confused as to why oxygen was not subtracted from the number of H atoms. Anyone know why oxygen is not subtracted from the total number of H a...

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For rounding your answer, I would wait to round until you get your final answer to ensure a more precise answer. Also, for sig figs you should look for the smallest sig fig value given in the problem. For instance, if the problem gave you a value with 5 sig figs and a value with 2 sig figs, your ans...

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I was always taught to go by the value with the least sig figs. So if one of the values in the problem was 4 sig figs and the other value was 3 sig figs, you would make your answer have 3 sig figs. Hope this helped! Also, if you need additional help with sig figs I recommend looking up sig fig works...

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It has also been some time since I have reviewed sig figs and I recommend that you look up worksheets online to practice the common sig fig rules. Your sig figs in your final answer should match the smallest sig fig value in the problem, but be sure to remember the sig fig rules. For instance, revie...

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In Fundamental E, Example E.2 states "Fluorine gas is so reactive that it reacts explosively with almost every other element. If you are working with fluorine and making quantitative observations, it is very important to know how much material you have. Calculate (a) the amount of F2 and (b) th...

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I spoke with one of the UA's and went to their Step-Up session on Tuesday and they really recommended taking advantage of the resources available. For instance, the Step-Up session really helped me solidify my confidence in certain skills and identify areas I am weaker in. They gave us a bunch of pr...

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I am having a hard time with Self Test L.2A in Fundamental L. The problem states, " Calculate the mass of potassium metal needed to react with 0.450 g of hydrogen gas to produce solid potassium hydride, KH." Do I have to first create the balanced chemical equation? If so, how do I do this ...

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