CHEMISTRY COMMUNITY

Jeril Joseph 1B

Well, the answer is in your question. My guess would be because N has the lone pair, which can be donated to another atom, which is the definition of a Lewis base.

Jeril Joseph 1B

I remember Lavelle said in lecture that the number of valence electrons is prioritized over the size of the electron when it comes to the strength of bonds.

Jeril Joseph 1B

Well, NH2NH2 is one compound. To understand it more, it can be written as N2H4. Using the Bronsted definition, you would know that because N2H4 is a base, it receives an H+ ion from H2O. It wouldn't receive two since NH2NH2 is one compound. So the conjugate acid would be NH3NH2.

Jeril Joseph 1B

Can someone walk me through step by step how to write the formula for the following compound: potassium hexacyanidochromate(III) I understand that the K goes first for potassium because it is a cation, and is outside the brackets because it is a separate word. I understand "hexacyanido" m...

Jeril Joseph 1B

I could be wrong, but from my understanding, Xe has a larger atomic radius compared to the other noble gases above the element. I wondered why Radon couldn't form bonds despite the large radius like Xenon, but because Radon is radioactive, that would mean that the element is unstable and would be un...

Jeril Joseph 1B

Chem_Mod wrote:Step up worksheet for this Monday

Question: For 1b, is there supposed to be a charge because I'm having trouble drawing the structure of CH2F as being neutral. Or is the molecule a radical?

Jeril Joseph 1B

A gold atom went to a bar, and the bartender said, "Au, get out of here."

Jeril Joseph 1B

So, I got a question on test 2 wrong regarding the calculation of the maximum number of H-bonds DNA(specifically the adenine and thymine base) can form with water molecules. Whoever got this question right or understands it now, how do you go about solving this question?

Jeril Joseph 1B

Oh!!! I figured it out. If the coordinate complex has a negative net charge, you add the -ate. That makes sense now.

Jeril Joseph 1B

So, the ion in question is [Co(CN)5(OH2)]2-. I know how to get the oxidation number, but I don't get why in this case you add an -ate to the end of cobalt when naming the ion. Is it because of the water?

Jeril Joseph 1B

So, on 9C.1 part a, I don't get how to find the change in ligands. So, I know to find the oxidation number of a metal, you use the equation (# of metals)(oxidation # of metal) + [sum of (number of ligands)(change in ligands)]= ion charge. With the hexacyanoferrate (II) ion, (Fe(CN)6)4-, I know ther...

Jeril Joseph 1B

So, on 9C.1 part a, I don't get how to find the change in ligands. So, I know to find the oxidation number of a metal, you use the equation (# of metals)(oxidation # of metal) + [sum of (number of ligands)(change in ligands)]= ion charge. With the hexacyanoferrate (II) ion, (Fe(CN)6)4-, I know there...

Jeril Joseph 1B

I hope this explanation helps. So, I believe this question is related to polarizing power. So, the cations that tend to have high polarizing power are the cations that have electrons concentrated near the nucleus(so the upper periods). With Mg2+, the cation will satisfy an octet with electrons conce...

Jeril Joseph 1B

Chem_Mod wrote:Answers to the last worksheet

Question: On 2c, wouldn't the answer be CO2 since there is a larger electronegativity difference. Because you said CS2 has more covalent character when the questions asks for a greater ionic character.

Jeril Joseph 1B

So, we need to consider that this compound has a net charge of 0. When doing the Lewis structure, it would only make sense to give Si two double bonds to both O atoms since giving those Oxygens a double bond will make their formal charge 0. As to the electrons not being drawn on the Oxygens, I don't...

Jeril Joseph 1B

The brackets are not used to indicate the number of added electrons per say, but the net charge of the compound, in this case -1. So, when drawing the Lewis structure, you should have a triple bond between Carbon and Nitrogen. Then, you put one lone pair on each atom. This is where formal charge com...

Jeril Joseph 1B

That would be correct, you remove electrons from the right-most side of the configuration or add them at the right-most side. I don't think there's any exceptions.

Jeril Joseph 1B

So, the question gives us the ground electron configurations of the ions. That means to get the original atom, we would need to add 3 electrons since these are M3 metals. Metals are typically cations, so that explains the plus 3. Part a, you add 3 electrons and get [Ar]3d^7 4s^2, which is Cobalt. Th...

Jeril Joseph 1B

Well, the electron configuration of Cu is [Ar] 3d^10 4s^1. So, Cu+ would be [Ar]3d^10 since you're taking away an electron. The principle quantum number would be n=3 since that's the coefficient of the d-orbital, and the angular quantum number would be l=2 since n-1 is equal to 2. Also, when l=2, an...

Jeril Joseph 1B

If you want to be in the study group, email me at jjoseph20@g.ucla.edu .

Jeril Joseph 1B

I believe this is due to the fact that with increasing molar mass and atomic size comes with an increase in electrons. With the increase in electrons, the atom has a higher interaction potential energy. Also, polarizability , which is the measure of the ability for anions to form dipoles or to be di...

Jeril Joseph 1B

To add on, ionic bonds form lattices(salts) as products that tend to be soluble in water while covalent bonds form molecules that are less soluble in water.

Jeril Joseph 1B

Well, the difference between the two would be that covalent bonds are the sharing of electrons between nonmetals; whether polar or non polar. Polar covalent bonds have to do with a lack of symmetrical distribution of electrons in the bond. As a result, the molecule formed from the polar covalent bon...

Jeril Joseph 1B

I don't think we can do that. Although they're isoelectronic, they don't necessarily have the same properties because they have a different amount of protons. I believe you would go off of the previous noble gas, which is Neon, and then write the 3s orbital and 3p orbital. So, the configuration woul...

Jeril Joseph 1B

Lewis structures are generally the form in which a molecules or compound's bonds can be displayed; whether that may be through covalent bonds or ionic bonds. The valence electrons are drawn with the elements in the compound and the bonds are noted using lines, one line per bond. There can be single,...

Jeril Joseph 1B

From my understanding, Manganese (Mn) would have 7 valence electrons: 2 from the electrons in the 4s orbital and 5 from the 3d orbital. I don't think you count the previous orbitals when considering valence electrons since that's already substituted by the adjacent noble gas, which is Argon. Those e...

Jeril Joseph 1B

Not sure if this will be a helpful explanation, but I'll try. So based on the principle quantum number, we know the element being discussed in the second row of the periodic table. This means that we're dealing with the s and p orbitals. So, we know that s has one orbital and p has 3 orbitals, equal...

Jeril Joseph 1B

So, I first converted the 225 mg. of cisplatin to grams and used the molar mass to convert the grams to moles of cisplatin. I then used the molarity= moles of solute/volume in liters equation to get the volume in liters I needed; plugging in the given molarity and the calculate moles of solute.

Jeril Joseph 1B

This was helpful. Thank you so much!

Jeril Joseph 1B

Isoelectricity is a property that certain elements and ions share in regards to the amount of electrons they have. So, Na+ would be isoelectronic to Mg2+ or F- or Ne. Hope this helps.

Jeril Joseph 1B

That is true. In order to manipulate the energy, you would need to use light of a different frequency since photons and electrons have a one photon one electron relationship. In doing so, a higher intensity(or an increase in photons) won't increase the energy of a light source to emit an electron.

Jeril Joseph 1B

Additionally, the electrons in the s-state are of lower energy levels and are closer to the nucleus, so they are prone to penetrating the nucleus.

Jeril Joseph 1B

I think the penetration refers to the attraction electrons in the s-state have towards the nucleus because of the opposite charges. However, that doesn't mean the electrons collapse into the nucleus since the change in velocity of an electron is greater than the speed of light.

Jeril Joseph 1B

Also, for the last question on the worksheet, shouldn't it be 10^15 since you're doing -18 - (-34)???? I got the other part of the answer, but is there an error with the exponent or is it just me?

Jeril Joseph 1B

Here are the answers for the first worksheet! I had a question on number 3 on this worksheet. So, I got up to getting 4.74 x10^39 s.^-1 mol. ^-1, but I don't know what to do from there. I attempted using stoichiometry to convert my units, but I don't know what to use to do that. Can someone help????

Jeril Joseph 1B

But when I looked at the answer to that question, it was [Kr]4d^5.

Jeril Joseph 1B

So, I don't get why the electron configuration for the ion Ga3+ has Kr instead of Ar. The answer is [Kr]4d^5, but I specifically don't get why there's the Krypton. Someone please explain!!!!!

Jeril Joseph 1B

The strategies I use are to prioritize certain elements over others, specifically the ones with low amounts, such as carbon, nitrogen, etc. If you balance those first, you can, then, focus on the hydrogens and oxygen since that may involve larger stoichiometric coefficients. And for extra precaution...

Jeril Joseph 1B

I have a question. So, if you are given a problem that has one value with 3 sig figs and another value of 4 sig figs, would you express your final answer using 3 or 4 sig figs? Would the amount of sig figs used change if there's more values given with 3 or 4 sig figs??? Sorry for asking.

Jeril Joseph 1B

This refers the posts that we make on this platform(chemistry community). It is 1 pt. per post for 6 pts. a week.

Jeril Joseph 1B

There is a negative sign present since you're decreasing energy levels to help excite an electron to be released. The electron is losing energy, so you wouldn't have a positive energy amount calculated if the electron energy is being lost. However, it's important to note that the equation mentioned ...

Jeril Joseph 1B

Well, there'd only be 0 kinetic energy for an electron when the energy of a photon is equal to the energy needed to remove an electron. So, refer to the E(photon)-E(work function)=E(excess). The excess energy is the kinetic energy. But the kinetic energy would be 0 when the photon's energy is at the...

Jeril Joseph 1B

Ok, that clears some things up. Thank you.

Jeril Joseph 1B

I know we haven't gone over this topic yet, but how would you calculate the principle momentum quantum number of an orbital. I know for an orbital angular momentum can be calculated using the square root(l(l+1) x (h)/2pi. For example, when given the orbital 6p, how would you calculate the principle ...

Jeril Joseph 1B

That's basically the reason. You substitute the v for the c/lambda, and because that's multiplied by h, you put them together to make E=hc/lambda. Then, if you want to solve for the wavelength, you cross multiply the equation, and divide both sides by e to get lambda=hc/e.

Jeril Joseph 1B

Nevermind, I figured it out. It's the mass of the electron, right?

Jeril Joseph 1B

Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1. What is the kinetic energy of the ejected electron? A. 3.01 x 1025 J B. 3.98 x 10-19 J C. 7.96 x 10-19 J D. 1.99 x 10-19 J E. None of the above How would yo...

Jeril Joseph 1B

Extensive property is something that can be changed based on the amount of a substance. So, the volume can change based on the amount of mL or m.^3 of a substance you put in a container. An intensive property is something that doesn't change, so density. That is because no matter how much the volume...

Jeril Joseph 1B

In order to find the molecular formula, the actual molar mass of the substance must be given in the problem. If that's not given, you don't solve for the molecular formula. If so, divide that value, which should be g.mol^-1, by the molar mass computed by adding up the atomic weight of the elements i...

Jeril Joseph 1B

Wait, never mind. I realized this is not part of the syllabus problems.

Jeril Joseph 1B

I came across this question and found that I had to calculate the percentage purity. Is that the same thing as percentage yield? If not, how would you go about solving this problem?

Jeril Joseph 1B

Someone can correct me if I'm wrong but yes, you would confirm the values you're using in the problem are 3 sig figs, in that scenario. So, you would round at the third place of the value. In this case, 15.999 would become 16. Hope this helps.

Jeril Joseph 1B

Copper (II) Nitrate reacts with sodium hydroxide to produce precipitate of light blue copper (II) hydroxide. (a.) Write the net ionic equation for the reaction. I thought the answer for this part was Cu(NO3)2 + NaOH --> Cu(OH)2, but then I realized there's no Na in the product. Why is that and why i...

Jeril Joseph 1B

Lauren Huang 1H wrote:Sometimes nitrogen can be an added reactant and product of the equation.

When would nitrogen be a product from a combustion reaction? Like, in what scenario?

Jeril Joseph 1B

A student prepared a solution of Sodium carbonate by adding 2.111 g. of the solid to a 250.0-mL volumetric flask and adding water to the mark. Some of this solution was transferred to a buret. What volume of solution should the student transfer into a flask to obtain (a.) 2.15 mol Na+ ...? Can someo...

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