CHEMISTRY COMMUNITY

Isabelle De Rego 1A

On the French toast exam (#28) it lists the answer as HI as the stronger acid.
I picked HCl because I thought that since HCl had more ionic properties, it would hog electrons and make it easier for H to disassociate in water. Wouldn't HI have a harder time doing so, and thus make it a weaker acid?

Isabelle De Rego 1A

If you're talking about in terms of quantum numbers, an orbital is quantum number n, which can be anything from 1 to infinity. A subshell depends on the orbital, because it can only be from 0 to n-1. You can think of orbitals as the different rows on the periodic table and subshells as the different...

Isabelle De Rego 1A

Essentially Lewis acids and bases are based on electrons, while the Bronsten ones are based on protons. So, a Lewis acid accepts electrons while a Bronsten acid donates a proton.

Isabelle De Rego 1A

You can think of it like how much the atom wants to hold onto its electrons. A small atom is much more likely to hold onto its electrons than a large one because it has way less electrons to begin with. Therefore a large atom is more polarizable, or it is easier to take electrons from it. A small at...

Isabelle De Rego 1A

In bio the bonds that we are talking about are usually occurring in water or some type of solution. It is because of the properties of water that make covalent bonds stronger than ionic bonds. Ionic molecules such as NaCl easily dissolve in water, but bonds with more covalent properties don't dissol...

Isabelle De Rego 1A

The presence of lone pairs determines whether or not the bond length is slightly less. So, if a lone pair is present then the bond angle will decrease.

Isabelle De Rego 1A

My TA said we won't be asked anything over the sp3d3 hybridization.

Isabelle De Rego 1A

It works for me to have the different structures memorized because then when I look at the regions of of electron density I can name the shape. So, since we know that 4 regions = tetrahedral, from there you can figure out the hybridization is sp3. You can think of it like, the superscripts of the hy...

Isabelle De Rego 1A

For determining the charge of the ligand you should calculate the formal charge. The charges of the ligands + the oxidation state of the central atom should equal the overall charge. So if the overall charge is 1+ and you have 2 ligands with a -1 charge, your oxidation state should be 3+. Hope this ...

Isabelle De Rego 1A

Just to elaborate, you would know that the structure is polar because it's tetrahedral. You know that its tetrahedral because there are four regions of high electron density. When you draw out the structure, the Cls will both pull away from C in the same direction.

Isabelle De Rego 1A

Why does ICl3 have 5 electron groups? ICl3 has 5 electron groups because of the two lone pairs. When we are counting the groups we don't only count the atoms. Remember that we are counting regions of "high electron density", so atoms and lone pairs are both included in this description. D...

Isabelle De Rego 1A

you can tell when a molecule has resonance usually when it has a double or triple bond. If you remember, there can be several resonance structures for one molecule, so it all depends on the placement of the bond. Also, resonance structures are in a lower energy state for the molecule. There is usual...

Isabelle De Rego 1A

Disassociation energy is the energy required to break a bond. For instance, if you were asked which bond had a higher disassociation energy, a double bond or triple bond, you would say the triple bond because it is harder to break. We have not gone over how to calculate disassociation energy so I wo...

Isabelle De Rego 1A

When doing the electron configurations, you should always do (just like you did!) put them in the order of increasing n. So, for example, if you had something with d or f block in it, you would put those before that row's s block or p block. For instance, Thalium would be [Xe]4f14 5d10 6s2 6p1.So, y...

Isabelle De Rego 1A

Just to clarify, a structure is more likely to contribute to a resonance structure if it has a lower formal charge? I initially picked the options with double or triple bonds to this question because when I think of resonance structures I think of moving around a double or triple bond, but I guess t...

Isabelle De Rego 1A

Nevermind, I get it. Nitrogen can't have an expanded octet.

Isabelle De Rego 1A

In the answer key, ClNO2 has only one double bond, but doesn't that break the formal charge rule, where the closest to zero formal charge is the best? If you give N, the central atom, two double bonds w the oxygens the formal charge is zero, but if you only give it one double bond it has a formal ch...

Isabelle De Rego 1A

N has a lower ionization energy than oxygen because it is more willing to give up its electrons. You can think about this relative to the noble gases, which have a full octet. The closer the atom is to the noble gas (having a full octet) the less willing it is to give up the electron. So, since nitr...

Isabelle De Rego 1A

So, I did my Lewis structure for NO+ and CO. I calculated the formal charges and everything added up but the back of the book has triple bonds occurring w NO+ and CO? For NO+, I do not see why O would have the positive partial charge because it is the more electronegative atom. Also, doesn't it make...

Isabelle De Rego 1A

This is probably referring to chlorine and its ability to reach the next or previous noble gas. So, the maximum negative oxidation number would be -1, since chlorine only needs to gain 1 electron in order to get its octet. However, chlorine must lose 7 electrons in order to reach the previous noble ...

Isabelle De Rego 1A

I talked to my TA and they said that for those problems with ammonium and stuff that we aren't expected to know it. I would focus more on the actual drawing of the lewis structures and not get caught up in the compounds.

Isabelle De Rego 1A

There is no particular rule, but since your central atom is typically the least electronegative one, it is the least likely to have a charge on it since the surrounding atoms are more likely to take the electrons.

Isabelle De Rego 1A

I do not think so, since all compounds have ionic and covalent properties. The difference between acids and bases is their tendency to give up or accept electrons. Those who give up electrons are a base and those who accept electrons are an acid.

Isabelle De Rego 1A

For question 3.33b they want the lewis structure for COCl2, when I originally drew this. I had carbon as the central atom, with oxygen and chlorine surrounding it, each with a single bond and 6 electrons around each of the three atoms. In the answers, the bond between carbon and oxygen is a double b...

Isabelle De Rego 1A

If this helps: The n, if it is higher that means that it is farther away, although it's energy level may be lower. For example, 3d is closer than 4s, but it's energy level is higher.

Isabelle De Rego 1A

We have not mentioned the F block in class so I doubt that we will be required to use it on a test. But, you can see that the f block is inserted before the 5d on the periodic table. So, since we fit "left to right" it makes sense that the f block would fill first. Sorry this explanation i...

Isabelle De Rego 1A

I'm not sure about the ion part, but all of the elements under Chromium and Copper (ex: Silver, Tungsten) would have the same type of ground state configuration where you want it to be d5s1, d10s1. So Silver is going to be [Kr]4d105s1.

Isabelle De Rego 1A

E=hv is the energy per photon, the units are J. E=1/2mv^2 is the kinetic energy that you use to find the energy of an ejected electron, usually in the photoelectric effect. You know that you can't use E=1/2mv^2 for photons because the equation asks for mass and photons don't have mass.

Isabelle De Rego 1A

So, you're trying to find the energy (E=hc/wavelength). So, first you would convert the wavelength from nm to m. Then plug that into E=hc/wavelenth. But now you want to find the energy that is emitted when there is 1 mol of photons. You know that the energy that you have just found is energy per pho...

Isabelle De Rego 1A

You only use De Broglie when you are finding the wavelength of something with a mass( wavelength = h/p) . p=mv, where m is mass and v is velocity. So, they would probably give you the two of the three variables and then you would solve for the third one.

Isabelle De Rego 1A

Too find the energy emitted by the photon you use the formula: E=hc/wavelength
First: convert wavelength from nanometers to meters (589*10^-9)
Then plug it into the equation: (6.626*10-34)(3*10^8)/(589*10^-9)
Energy= 3.37*10^-19

Isabelle De Rego 1A

Yes, watch out for calculating the kinetic energy (1/2mv^2) of an electron, in which you will need the mass of an electron. Also, if you need to calculate the wavelength of an electron, you would use de Broglie's equation, not c=h*lambda because an electron has a mass, whereas a photon's mass is neg...

Isabelle De Rego 1A

A lamp rated at 32 W (1 W 1 J s 1) emits violet light of wavelength 420 nm. How many photons of violet light can the lamp generate in 2.0 s? How many moles of photons are emitted in that time interval? I have so far: used the wavelength (converted to meters) to find the energy of the light. After mu...

Isabelle De Rego 1A

I'm having trouble determining when to use the equation E=hc/wavelength. I understand what the constants are h (Plank's), c (speed of light), and wavelength, but I'm not entirely sure how to implement it. What makes this equation better than using E=frequency*h or c=wavelength* frequency? To be comp...

Isabelle De Rego 1A

I'm not sure, but I think the two are equivalent in this case. Since # of photons = intensity of light and quanta measure "how much", if you put quanta in terms of light the two are synonymous.

Isabelle De Rego 1A

I'm pretty sure that you only have to find the amount of moles of KOH by multiplying the molarity by the volume (don't forget to convert mL to L!)

Isabelle De Rego 1A

The electrons are displaced by the photons if the photons have a high enough energy, aka "threshold energy". The photons and electrons are not interchangeable and are definitely different particles.

Isabelle De Rego 1A

Yes, I think so. So, if frequency increases that makes the "period"/ "wavelength" shorter.

Isabelle De Rego 1A

I'm not sure if this is what you are asking but: if you are given the amount in grams of a compound you should convert that to moles and then convert the amount of moles of a compound into moles of that particular compound by looking at the formula given (like how there are two moles h in h20) . If ...

Isabelle De Rego 1A

Light has photons, which are particles and light also has wave-like properties. Since intensity is equal to energy in a wave, light exhibits wave like properties. However, light is made up of photons and at a certain intensity, even thought there are more photons the overall energy is not affected. ...

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