CHEMISTRY COMMUNITY

Arieanne De Guzman 2J

What factors do we consider when we are determining if something is acidic, basic, or amphoteric? For example, for 6A.17 in the textbook it asks: State whether the following oxides are acidic, basic, or amphoteric: (a) BaO; (b) SO3; (c) As2O3; (d) Bi2O3. I know there are multiple ways of determining...

Arieanne De Guzman 2J

That's how I've been comprehending it! I usually think of neutralization reactions between strong acids and strong bases in this formula: Acid + Base -> Salt + Water. It makes sense that strong acids and strong bases would produce water because all the strong bases have OH and the strong acids have ...

Arieanne De Guzman 2J

Hi, I'm a little confused on this question: In each of the following salts, either the cation or the anion is a weak acid or a weak base in water. Write the chemical equation for the proton transfer reaction of this cation or anion with water: (a) NaC6H5O; (b) KClO; (c) C5H5NHCl; (d) NH4Br. How woul...

Arieanne De Guzman 2J

Hi! Thank you for your further clarification on ligands. Going off of H2O, because the two lone pairs are on the same atom (O), electron-electron repulsion causes H2O to be monodentate instead of bidentate because it can technically only have one binding site? Does this also imply that for a ligand ...

Arieanne De Guzman 2J

A polydentate ligand will have more than one binding site/more than one atom that can donate their lone pair. A monodentate ligand will have one binding site/one atom that can donate their lone pair. Drawing the lewis structure can help you see which atoms have a lone pair and then you can distingui...

Arieanne De Guzman 2J

I have the same question as well. I wanted to add on and ask what happened to the Cl for part e and the (NO3)2 for part f? Why are they excluded from the chemical reaction?

Arieanne De Guzman 2J

I definitely feel like the formulas would be the best way to distinguish between acids and bases. A good rule of thumb is that acid formulas start with an H and donate their proton, whereas base formulas end with OH and will accept a proton. I would say an expectation to this would be CH3COOH, aceti...

Arieanne De Guzman 2J

It is best to memorize all the common strong acids because pretty much everything else would be considered weak. The common strong acids (according to the textbook) are HBr, HCl, HI, HNO3, HClO4, HClO3, H2SO4. It would be helpful to first identify which compounds are the acids and which are the base...

Arieanne De Guzman 2J

Hi! We know that Cl2 would have an overall charge of -2, however, because the coordination compound's overall charge is 0, then the charge of [Co(NH3)5Cl] would have to be equal to +2. We would set up an equations like this: x + 5(0) + 1(-1) = +2. When we solve for x, we get an oxidation state of 3!...

Arieanne De Guzman 2J

Hi! I'm quite confused about the last two homework questions. What does it mean for a species to be more or less predominant in a solution?

Arieanne De Guzman 2J

Hi, I was wondering how would you know if a ligand is polydentate through looking at the formula of the coordination compound?

Arieanne De Guzman 2J

If I'm interpreting your question correctly, H3O concentration wouldn't always the same because there may be questions where you may have to find H3O based on pH (which would be provided) or vise vera: find pH through using H3O (which would be given). Let me know if this was the answer you were look...

Arieanne De Guzman 2J

I think if we had a question dealing with experimental bond angles, we would have to be given them or we would be asked to give an estimate of them. We can find an estimate of the experimental bond angles by determining the arrangement of electron density and the actual shape of the molecule (which ...

Arieanne De Guzman 2J

I like to think of the valence bond theory as the quantum mechanical definition of the distribution of electrons in bonds. In the lewis structure model, it represented localized electrons. However, we know that an electron's location can only be described as the probability of finding it in a region...

Arieanne De Guzman 2J

I think sp3 was so common just because of the molecules we were dealing with (I noticed the pattern too). I believe we will be encountering molecules that have other hybridizations because in a workshop I went to, as well as textbook problems, there were hybridizations other than sp3 that was presen...

Arieanne De Guzman 2J

Can someone explain what it exactly means for dipoles to 'cancel out'? I have just been thinking that if dipole moments are going in opposite directions and are of the same strength, then the dipoles cancel out and the molecule is nonpolar. Am I comprehending this correctly? How do you personally de...

Arieanne De Guzman 2J

Hi! For #12 in Sapling for this week's problems, do we first have to find the molecular formula from percent mass composition to draw the lewis structure? Here is the exact question as well: An organic compound that is distilled from wood has a molar mass of 32.04 g/mol. Its composition by mass is 3...

Arieanne De Guzman 2J

I'm curious of this too. I'm taking 3 other classes yet still am doing all the textbook problems, workshops, step-ups, going on chem community, Sapling, pretty much all the resources and I still can't get scores that reflect my knowledge/hard work. It's getting really discouraging ):

Arieanne De Guzman 2J

Yes, the parentheses do help in figuring out which atoms bond with others! Since NH2 is in parentheses, you would assume that those two hydrogens are specifically bonded to the nitrogen. For part c, how do I know which atoms bond with others? Do the parentheses help? Draw the complete Lewis structur...

Arieanne De Guzman 2J

I forgot to mention that I do attend workshops as well! Those have definitely been one of the most helpful resources. Now that both midterms are out of the way, I wanted to ask how are you all preparing for the final exam? I feel like there is definitely a lot of information we're going to need to c...

Arieanne De Guzman 2J

This objective is referring to how the wavefunction squared gives us the probability of finding an electron in a certain region! Can someone explain the information being asked in this objective "Describe the interpretation of atomic orbitals in terms of probability." Not sure what the pro...

Arieanne De Guzman 2J

Now that both midterms are out of the way, I wanted to ask how are you all preparing for the final exam? I feel like there is definitely a lot of information we're going to need to cover and I wanted to hear your best tips for being able to comprehend and memorize all the concepts we've learned thro...

Arieanne De Guzman 2J

Yes, you are correct that Be would have a greater EN but that does not necessarily mean it'll have a bigger EN difference. Be would be closer to Br's EN than Ba is, thus the EN difference in Be-Br is actually less than Ba-Br. This is because Ba is in the bottom left of the periodic table, meaning it...

Arieanne De Guzman 2J

Boron and Aluminum don't need a full octet because they are stable with 6 electrons. Thus, you will typically find them making 3 bonding pairs with other atoms instead of 4 bonding pairs (which make the octet) like carbon. Hope this helps! Hi! I know that Boron and Aluminum do not need to have a ful...

Arieanne De Guzman 2J

So the textbook equation is FC = V - (S/2 + L). V = valence electrons, S=shared electrons, and L=lone pairs. The reason why FC = (# of valence electrons) - (number of dots and lines) still works is because in the textbook equation, we are dividing the shared electrons by 2. This is why we only count...

Arieanne De Guzman 2J

Yes (: Because kinetic energy is the excess energy that results when the energy of the photon is greater than the work function.

Arieanne De Guzman 2J

Electronegativity will help you classify what the bond is. The difference in electronegativity between two atoms will tell you if they would have a covalent or an ionic bond! If two atoms have similar electronegativities, or closer to one another in the periodic table, they are more likely to have a...

Arieanne De Guzman 2J

If you're referring to the bond lengths such as N-O or C-O in your resonance structures, Google will be your best friend for that. You would only be able to find the true bond length through experimental results. To add onto this, you could find the bond length of the resonance hybrid structure, bec...

Arieanne De Guzman 2J

Try a double bond with the other oxygen atom! This is still considered a resonance structure because you're changing the bond with the other oxygen and therefore is considered a different structure than the first structure (which was given). For question number 4 in the Sapling HW, I am asked to to ...

Arieanne De Guzman 2J

I apologize for misunderstanding your question! You are indeed correct that the electron configurations do not have electrons in the d subshell and that it only comes up in n=4. However, it is important to note that the 4s subshell gets filled up before the 3d subshell. This is because it has less e...

Arieanne De Guzman 2J

The only formula I can think of is to use FE = (# of atom's valence electrons) - (# of lines and dots). It's less complicated than the formula from the textbook. I do believe you have to draw out the resonance structures, plus its good practice for exams. Here are some tips to remember while drawing...

Arieanne De Guzman 2J

I think more practice with lewis structures would be the best way to get faster at making resonance structures as a whole. The more you do, the more you'll start to see what bonds give the best formal charge, for example, oxygen with having a double bond to another atom gives a formal charge of zero...

Arieanne De Guzman 2J

The difference between ionic and covalent lewis structures is the idea that atoms in ionic compounds do not share electrons, one gives off its electron to another. On the other hand, atoms in covalent compounds do share electrons. In covalent lewis structures, you will see the typical lines that con...

Arieanne De Guzman 2J

The problem is asking you to find the energy of the incident photons in order to determine the electron affinity (which is the difference in energy between the incident photons and the energy of the ejected electrons). You're given the incident wavelength, so you can convert to frequency and use E=h...

Arieanne De Guzman 2J

The quantum number ℓ tells us the subshell, where each subshell contains one or more orbitals. ℓ=0 corresponds to the s subshell, ℓ=1 corresponds to the p subshell, ℓ=2 corresponds to the d subshell, ℓ=3 corresponds to the f subshell, so on and so forth. Each subshell contains a certain number of or...

Arieanne De Guzman 2J

"1B.15 The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x10^3 km/s . (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50 x10^16 Hz. How much energy ...

Arieanne De Guzman 2J

Here are the steps I took into solving this problem: 1. Find energy of incident photons by using the incident wavelength, converting into frequency, and then using E=hv to find the energy. 2. Plug in values into electron affinity = energy of incident light (found in step1) - energy of ejected electr...

Arieanne De Guzman 2J

Hi! The quantum number n tells us how many subshells make up that shell. For example, n=1 has one subshell: 1s, n=2 has two subshells: 2s, 2p, n=3 has three subshells: 3s, 3p, 3d, and so on. Hope this helps! Hi so I was wondering if someone could explain to me why n=3 has sub shells 3s, 3p, and 3d. ...

Arieanne De Guzman 2J

Hi! First, recognize what you are given and what you're being asked of. Light is hitting a zinc atom and an electron was ejected. You are given the velocity of the ejected electron, the work function for zinc, and you are asked to find the frequency of the light hitting the atom. You can use the vel...

Arieanne De Guzman 2J

Just make sure that n2 is greater than n1! What has helped me was looking at it as electrons move from a higher energy state to a lower energy state. In this way, I wouldn't end up with a negative number. Hope this helps a little!

Arieanne De Guzman 2J

I believe you answered the question for yourself! Like you said, the higher the energy, the shorter the wavelength. n=6 to n=1 has a higher energy emission than n=6 to n=5, thus the wavelength would be shorter. Hope this helps (:

Arieanne De Guzman 2J

Because there is only one electron in hydrogen, that means there are no electron-electron repulsions and that every subshell will have the same energy (degenerate). Multi-electron atoms however have electron-electron repulsions that give rise to different energies in each subshell due of the shieldi...

Arieanne De Guzman 2J

Since you are dealing with electrons which has a mass, you have to make sure you use De Broglie's equation to solve for wavelength and not c/freq. You only use c/freq to solve for wavelength when you are dealing with light, which doesn't have a mass. Hope this helps (:

Arieanne De Guzman 2J

Hi! And yes, essentially the difference between the two is just as you said, one deals with one atom and one deals with molecules (multiple atoms). The importance of atomic/molecular spectroscopy is that it tells us the structure of electrons of certain atoms/molecules. Because each atom/molecule ab...

Arieanne De Guzman 2J

"If an object is placed in their path, they cast a shadow. " How does this property of cathode rays represent a 'radiation model'? Is a radiation model a wave or a particle model, or both?

Arieanne De Guzman 2J

The electron in a hydrogen atom is excited to the n=5 shell and emits electromagnetic radiation when returning to lower energy levels. Determine the number of spectral lines that could appear when this electron returns to the lower energy levels, as well as the wavelength range in nanometers. For so...

Arieanne De Guzman 2J

When you divide the total energy in J by the work function which is in J per photon, J cancels out and you're left with photons. Since we know that one photon removes one electron in a 1:1 ratio, the number of photons is equal to the number of electrons!

Arieanne De Guzman 2J

I believe Dr. Lavelle went from wavelengths to frequencies because he assumes that we know the the relationship between the two and how they are inversely proportional. The wavelengths in the diagram represent the frequencies of the light. Light with a shorter wavelength (let’s say in the gamma ray ...

Arieanne De Guzman 2J

Hi! To add onto the explanations, I thought that including a diagram to get some sort of visual helps a lot with understanding both series. Here is a link to an image that was very helpful for me! https://haygot.s3.amazonaws.com/questions/625565_596440_ans.gif It includes another series that we have...

Arieanne De Guzman 2J

Hi! I was wondering if anyone could breakdown each component of the Rydberg Formula? I get that it is a formula we have to use to predict a wavelength of light, but I would like to know what each part of the formula represents. Thanks!

Arieanne De Guzman 2J

I believe it is recommended to do these textbook problems for practice, but you do not have the do every question. I typically just pick questions that seem to correlate more with what we're learning in the lectures and on our homework questions on Sapling so I can master the concepts. If I come acr...

Arieanne De Guzman 2J

Hi! Essentially the ±10 g is to account for experimental errors that may have caused the caproic acid's molar mass to be 10 grams more or 10 grams less than what the actual molar mass is. It gives a range of where the true molar mass may be, which would be between 100g/mol to 120g/mol. However while...

Arieanne De Guzman 2J

Since all of the reactants and products are in a gaseous state (which is referred to by (g) in the chemical equation), there isn't a specific gas the problem is referring to. Therefore, you would just add up the stoichiometric coefficients of both the reactants and products and subtract the moles of...

Arieanne De Guzman 2J

Here are the steps I took in solving this problem! 1. Convert data given (2.275g CO2 and 0.929gO2) into grams of carbon, hydrogen, and oxygen (the molecules in caproic acid) a. Convert 2.275g CO2 to moles of CO2 (divide by molar mass of CO2) b. Convert moles of CO2 to moles of C (multiply by 1 mol C...

Arieanne De Guzman 2J

Yes they are reactants! When a problem states "burned/reacted with an excess _____", excess means that there is more molecules of that specific reactant in the chemical reaction (some of which will be unused after the reaction has taken place). The other reactant would be the limiting reac...

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