CHEMISTRY COMMUNITY

DTingey_1C

Ryan Chew 1C wrote:Yes, you are correct. Each O atom counts as two H bonding sites due to the two lone electron pairs.

Ok but when I counted each O as two bonding sites, then added the H and N bonding sites both as one bonding site each, I got 12 instead of the answer, 11.

DTingey_1C

Hydrogen bonding can occur between molecules of the same substance, or with molecules of other substances, just as long as the H atoms are bonding with N, O, or F atoms.

DTingey_1C

Ion-dipole is weaker than ionic, but stronger than the rest.

DTingey_1C

On Test 2, question 7A asks to give the total number of bonding sites for Xanthin. Is one hydrogen bonding site normally one N, O, or F with a lone pair, or one H atom? Because I counted these on the Xanthin molecule and get 9, but my TA wrote 11 as the correct answer. I don't know, is it possible f...

DTingey_1C

Yes isn't SO3 with one double bond more unstable than SO3 with 3 double bonds? Maybe this is because it wouldn't act as a lewis acid anymore.

DTingey_1C

If the strength of binary acids increases with elements across a period because of the increase in electronegativity, why does the strength of binary acids also increase with elements down a group if electronegativity typically decreases down a group? Thanks

DTingey_1C

You basically just find the radius of each atom that is bonded together in the table and you add them together. The sum of the covalent radii is the bond length. We will probably never see this on any test because it is a weird question since you need a table to calculate the values.

DTingey_1C

Additionally, the more double bonds, the stronger the bonds are on the molecule overall. So a tetrahedral with three double bonds will have stronger bonds than an identical tetrahedral with only one double bond.

DTingey_1C

If it makes it easier to understand, think of the hybridization as something akin to the shape of the molecule. sp3 means there are 4 regions of e- density, meaning the shape can be AX4, AX3E, AX2E2, ect. This means that you can almost name a molecule as a tetrahedral by knowing that its hybridizati...

DTingey_1C

The book defines a weak/base acid as a compound that only deprotonates/protonates a small fraction of molecules in a solution. But, are there examples of acids or bases that deprotonate/protonate a larger percentage, but not necessarily 100% of molecules in a solution. Can a base that only deprotona...

DTingey_1C

I don't understand what makes something basic or acidic. Are bronsted bases very basic on their own? Or are they only basic when they have water and acids to interact with? Thanks.

DTingey_1C

Is it necessary to memorize all of the Bronsted acids and bases that have 100% deprotonation/protonation and their molecular formulas? Thanks.

DTingey_1C

In question J.9 A, you are asked to identify the salt formed from acid-base neutralization reactions. In A, potassium hydroxide and acetic acid are used. But, in the answers, it formats the potassium separate from the acetic acid and separated in salt form, like this: CH3COOH + K+ + OH- ---> K+ + CH...

DTingey_1C

Is it important that we memorize all of the charges for the ions (such as nitrate, nitrite, phosphate, ect)? Or will we be given the charges on the test? Thanks.

DTingey_1C

In an acid-base reaction, such as:

HBr = K+(OH)- --> KBr + H2O

What is forcing the H atom in the HBr to switch with the K atom in the K+(OH)-? Is switch the wrong word to use? Is there a better way to understand this reaction conceptually? Thanks.

DTingey_1C

In problem J.1, you are asked to identify bronsted acids and bases. It says NH3 is a base and H2SO3 is an acid. How can you tell the difference? Is it because NH3 has a lone pair that allows it to receive H+ ions? Or is it because it has 3 H atoms and usually molecules with more than 2 H atoms are b...

DTingey_1C

Do single e- in radicals repel atoms and other e- weaker than lone pairs do?

DTingey_1C

H20 has a angular, bent shape to it, which is why its polar. But, why don't its lone pairs repel each other and give it a linear shape (where the lone pairs are 180 degrees from each other and the H atoms are 180 degrees from each other)? Like this: ___LP H-- O --H ___LP LP = lone pair O and H = ato...

DTingey_1C

The book contains all of the different molecular shape names (linear, see-saw, T-shape, ect). Do we have to memorize all of these?

DTingey_1C

I understand the photoelectric effect proves that waves have properties that make them similar to matter, but is there an experiment that proves that matter has properties similar to waves as well?

DTingey_1C

I understand that we need to know how to calculate the energy of an e- in a particular energy level of a H atom, but would we ever need to apply a different equation for a different atom on a test? How do the multiple e- effect the equation?

DTingey_1C

What do the lines represent? Do each of the lines represent a particular wavelength of light that causes an e- to be ejected or is it the space between the lines that ejects an e-?

DTingey_1C

If a large object was moving so slow that it had an extremely small momentum despite its mass, could it theoretically have a measurable wavelength?

DTingey_1C

What is the difference between the energy of an e- in H-atom orbitals and the orbitals in an atoms with multiple e-?

DTingey_1C

I know that Lavelle said that lone pair e- impact the shape of the molecule, but is the impact of a greater or lesser magnitude than if an atom were in the place of the lone pair? I hope this isn't too confusing.

DTingey_1C

Is it necessary that we know the exact angles created by each of the different molecular shapes?

DTingey_1C

He explained in class that we do not need to know the exact angles in the model, but we should know how the radii of atoms and other factors might impact the angles. Hope this helps.

DTingey_1C

How do you do B for this problem:

On the basis of the expected charges of the monatomic ions, give the chemical formula of each of the following compounds:

B: Indium (III) sufide

DTingey_1C

And why is copper: [Ar] 3d10 4s1 instead of [Ar] 3d9 4s2?

DTingey_1C

Why is the e- configuration of Ni: [Ar] 3d8 4s2 while Pd is: [Kr] 4d10? Why isn't Ni [Ar] 3d10 like Pd is?

DTingey_1C

Why does is Ga, in problem D, form ions with a +3 charge? Why not -5 so it becomes stable?

DTingey_1C

I believe Lavelle mentioned this odd configuration along with one other one that I am forgetting right now. He said that these two configurations are anomalies that we just have to memorize without much further explanation. Some areas of chemistry (and science in general) are proven experimentally b...

DTingey_1C

When ionic or covalent bonds are formed, does the "probability area" of an atom's e- shift toward the atom it is sharing e- with (or giving e- to)? If so, how is it effected by the bond?

DTingey_1C

Are covalent bonds only formed by two non-metals? Or can other types of elements be involved and its just more unlikely?

DTingey_1C

Lavelle mentioned 2 odd e- configurations in lecture that don't follow the normal rules of e- configuration. Is it necessary for us to memorize these configurations for the test or will they never show up?

DTingey_1C

First count the e- in all the atoms and add them together then add the charge of the molecule. When drawing the placement of the atoms, put the one with the lowest ionization energy in the middle and the other atoms around it (hydrogen is always on the outside. Then draw the e- around the atoms (onl...

DTingey_1C

Thanks for the article that's really interesting

DTingey_1C

I don't fully understand what the equation means conceptually. I understand that the equation represent the range of momentum and location of an electron, but what does this mean? Since the location is represented by "x," does this mean it is a distance? Or is more of an area of probabilit...

DTingey_1C

Since the DeBroglie equation requires a momentum to work, how does EM radiation have a wavelength? I thought light was massless, so how would it have a momentum that could be plugged into the equation?

DTingey_1C

Also protons do have a mass, so they could be theoretically applied to the equation.

DTingey_1C

The equation is only practically used for objects that have an observable wavelength. Since objects like cars have a velocity and mass, and therefore momentum, they have a wavelength when plugged into the equation. But, since the mass of the car is too great, the momentum is too high and the wavelen...

DTingey_1C

The are not related because the E's (energies) are different forms of energy. In E=hv, E represents energy per photon, which is unrelated to mass. Whereas in E=mc^2, E represents units of energy (not per photon) and is directly proportional to mass. So, there isn't a relationship and hv can not equa...

DTingey_1C

How do you solve this problem, I keep getting non-whole numbers but the answer is n=6 :/.

An excited hydrogen atom emits light with a frequency of 1.14 x 1014 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?

Thank you

DTingey_1C

E=hv lambda*v=c E=h*(c/lambda) lambda=(hc/E) Ultimately, you use equations to find unknown variables. So, if you know what the variables represent, and you understand how to find the variables out of the problem by manipulating other equations, you'll be fine. Here is what the variables mean: E = En...

DTingey_1C

Metal needs a certain energy of light in order to remove electrons from its surface. The higher the frequency, the higher the energy. The energy of the light has to exceed a threshold energy needed to remove electrons from the surface of the metal. Once the threshold is exceeded, one electron will b...

DTingey_1C

Yes it is a one-to-one reaction. Increasing the intensity of a wave increases the electron interaction because the amount of photons is increased.

DTingey_1C

D. λv = c is the correct answer because it doesn't have to do with the photoelectric effect equation or any of its derivations. The equation shows the relationship between a wave's frequency and wavelength.

DTingey_1C

Frequency is the amount of cycles per second while wavelength is the length of the wave. So, they have an inverted relationship. Amplitude is the height of the wave, so it is unrelated to frequency or wavelength. Velocity is the speed of a particle in m/s.

DTingey_1C

Do we need to memorize all of the different prefixes(giga, kilo, nano, ect.)? Or will it be given to us on a test? If so do u have any easy ways to memorize them? Thanks.

DTingey_1C

This was pretty much answered but I'd like to add that if a constant is used (like pi) you should use at least 3-4 sig figs. So, it would be 3.142 for pi.

DTingey_1C

I don't know how the reaction is impacted, but my TA said that you should get in the habit of doing it because it'll be important in the future. So, I'm assuming that it's important to do on tests as well.

DTingey_1C

This is the way I do it: 1. First find the moles of each reactant by dividing the grams of the reactant by its molar mass. 2. Use the moles of each reactant to calculate how much product can be produced (it doesn't matter which product you chose as long as you keep it consistent for all of the react...

DTingey_1C

One easy way to do conversions that I learned in high school is to think of the prefixes in a line, so like this: Kilo, hecto, deca, base unit, deci, centi, mili, micro... ect And think of these in terms of their respective numbers like this: 10^3, 10^2, 10^1, 10^0, 10^-1, 10^-2, 10^-3, 10^-6 And, w...

DTingey_1C

Here is the problem E19 from the textbook: A report stated that the Sudbury Neutrino Observatory in Sudbury, Canada, uses 1.00×10^3 tonne (1t=10^3kg)of heavy water, D2O, in a spherical tank of diameter 12 m to detect neutrinos. The density of normal water (H2O) at the temperature of the tank is 1.00...

DTingey_1C

Yes, Lavelle said that there will be all of the constants and basic equations we go over.

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