CHEMISTRY COMMUNITY

AustinGrove3B

Elle_Mendelson_4I wrote:Will someone please explain number 20?

Iron actually likes to have 6 bonds... coordination number 6. This Fe in the structure is bound to 4 nitrogens, but will also bind to a histine group and a structure that binds to oxygen, creating 6 bonds. 6 bonds creates an octahedral structure.

AustinGrove3B

Elle_Mendelson_4I wrote:Will someone please explain 22

Myoglobin has one heme group, which is what that Fe N structure is. Each heme group can hold one oxygen, therefore myoglobin holds 1 oxygen. Hemoglobin has 4 heme groups.

AustinGrove3B

For sulfur, it has two extra electrons because that would result in the sulfur atom having a full shell. For the Cd, it will give up two electrons because that will result in the 3rd shell being full... remember the configuration is ... 3d10 4s2

AustinGrove3B

You would have to count the amount of electronegative atoms with lone pairs. The lone pair would form coordinate bonds with the metal. For the first question, there are 3 N in the equation, so it will form three bonds. H20 has one O, so it will form one bond. CO3 has two Os with lone pairs, so it ca...

AustinGrove3B

There unfortunately is not just one way that I can tell you how to name acids. There are a set of rules, similar to the naming of a compound, that tell you what the name of the acid would be. They have rules for when the anion ends in ate vs ite etc.

AustinGrove3B

Yes. Double bonds and triple bonds cannot rotate. The single bond can rotate and is able to have 3-d structures. The double/triple bonded atoms will be in the same plane as each other.

AustinGrove3B

A heme group is an iron atom surrounded by 4 nitrogen atoms. Iron likes to have 6 bonds, so one of the other bonds is a massive histine group... but for biology, the most imoportant function of heme groups is the 6th bond--the oxygen. Heme groups are present in hemoglobin (in blood cells) and that i...

AustinGrove3B

Lewis Acid: the molecule that accepts a lone electron pair
Lewis Base: the molecule that donates a lone electron pair

Bronstead Acid: Molecule that donates hydrogen ions
Bronstead Base: molecule that accepts hydrogen ions

AustinGrove3B

I would be surprised if we had to draw lewis structures that were rings. They are common in organic chemistry, but that is much more complicated than the structures we have been drawing in class.

AustinGrove3B

All of the molecules will have hybridized orbitals. You have to pick the one that best explains the structure.

AustinGrove3B

I believe it is conventional to draw the dipole arrows towards the more electronegative atom... so the atom with the partial negative charge. I would probably recommend doing that on the test, especially because Dr. Lavelle did it that way.

AustinGrove3B

In other words, it is a model that explains how/why the molecules have the shape that they do. If you don't like the phrase VSEPR model, you could just think "molecular shape" instead. It is all the stuff we have done in class the last 2 days regarding trigonal planar, tetrahedral, octahed...

AustinGrove3B

If you look up "VSEPR Structures" on the internet, it will show you which molecular shape corresponds to each of those. You likely are a little ahead in the homework compared to what we have gone over in class.

AustinGrove3B

Because they do not actually have a bond. Remember that a bond in the molecular structure actually means they are sharing two electrons. But in this ionic compound, the Cl completely steals the electron. So they are attracted to each other because they are opposite charges (cation-anion), but are no...

AustinGrove3B

He said that if we are running on schedule, we will not have class Wednesday. But if we started to fall behind on molecular shapes, we would have to have class that day.

AustinGrove3B

They are all interactions that give rise to attractive forces.

AustinGrove3B

In general, molecules with bonds that have higher covalent character are LESS soluble in water. Molecules with bonds with low covalent character / high ionic character are MORE soluble in water. A good way to remember it is that salt, NaCl, is an ionic compound and is extremely easy to dissolve in w...

AustinGrove3B

It is -20 kJ / mol. This is stronger than the dipole-dipole interactions, but not as strong as a full covelent/ionic bond.

AustinGrove3B

This usually happens to atoms like Boron, which only have 3 valence electrons. In the molecule BF 3 , there are 24 valence electrons. Boron will share its 3 valence to give the Fluorines a full octet, and that is a stable molecule. There will be 3 single bonds (octet for fluorines and 6 electrons to...

AustinGrove3B

More specifically, cations are elements that have lost electrons, therefore having a positive charge. Anions are elements that have gained electrons, therefore having a negative charge.

AustinGrove3B

The resonance structure will have an average bond length closer to the more "dominant" resonant structure... This will be the structure that has formal charges of the molecule closer to 0.

AustinGrove3B

It has to do with the fact that when you add an electron to C, it goes in the 3rd P subshell (previously unoccupied). When you add an electron to N, it has to pair up with another electron in the p shell. The energy released in the C case is larger.

AustinGrove3B

The lewis structures are just quick drawings of the shape of the molecule. You would not have to get detailed enough to show different bond lengths. The overall goal is to just show the relationship between the different atoms.

AustinGrove3B

These are general trends that summarize the whole periodic table. They trends probably to not take into account every factor that would affect ionization energy. There are always exceptions

AustinGrove3B

It does not matter. People usually tend to organize them so the unfilled sides match the other unfilled size, so geometrically they look like they should bind together. But it does not matter.

AustinGrove3B

Having full or half full subshells is less potential energy than having semi full subshells. For that reason, sometimes electrons will be taken from the s subshell to fill the d subshell.

AustinGrove3B

I think there would be 1 nodal plane in each p orbital. There are 3 orbitals in the p-block, so technically there would be 3 total nodal planes- 1 in each orbital.

AustinGrove3B

You do need to know all the fundamentals of this. Almost all of the math and equations we have been learning have actually all been related to the atomic spectra. All the equations with energy, bohr frequency condition, de broglie, rydberg equation etc all have applications with atomic spectra. Reme...

AustinGrove3B

Ep = E2 - E1 where Ep is the energy of the photon, E2 is the energy of the excited electron, and E1 is the energy of the electron before excitation. In concert with our knowledge of E=hv, we can mathematically iterate this phenomenon known as Bohr's Frequency Condition that solves for the frequency ...

AustinGrove3B

Dr. Lavelle said in class that there is no required relation between a ml and the orbital. For example, when l=1 and ml = -1,0,1..... that would usually be read as p x , p y , and p z . But thats just because we read that from left to right. If you wrote ml= 1,0,-1 and had the order of p x , p y , a...

AustinGrove3B

The total amount of energy is 11J. You calculated the amount of joules per photon to be 1.07 x 10^-19. So dividing 11 by 1.07 x 10^-19 gives the amount of photons.

Think about it this way: the amount of joules per photon x number of photons must = total joules

AustinGrove3B

It can be applied to anything as small as electrons or something very large, such as a car. There is no restriction.

Having said that, the wavelength of a person or a car is so small that it is negligible. Only with very small objects like electrons will the wavelength be measurable.

AustinGrove3B

Dr. Lavelle said he does not require you to memorize information like constants and formulas. However, you should probably be familiar with the relative energies of each series, such as which series is visible light and which is uv-- so that you can kind of check your answer on a test to see if it m...

AustinGrove3B

The question is confusing because the "extent of the change" is a really weird way of saying the slope of the graph. It wants you to see what would happen to the slope of the wave when freq decreases (wavelength increases) and therefore slope decreases (less steep). Its just a poorly worde...

AustinGrove3B

Intensity of the light is directly proportional to the number of photons. So an intense light source will have more photons. Keep in mind that the intensity of the light has nothing to do with how much energy is in each photon (E=hv). In terms of the photoelectric effect, shining a high intensity, b...

AustinGrove3B

This is because for He +, z is equal to 2. So 2^2 =4. So the equation is 4 * R (energy difference). But I believe Dr. Lavelle said he would only test us on hydrogen, which has a z=1, so you can ignore that part of the equation.

AustinGrove3B

Its probably a good idea to just memorize the minimum and max frequency of the visible spectrum. But Dr. Lavelle insists he isnt going to make anybody memorize details such as that.

AustinGrove3B

Yeah Id assume the TA hands it back in discussion when they are done grading. I personally have not received any homework back yet.

AustinGrove3B

Electrons are always acting as both. They have a mass, which prove they are a particle. But they are also always moving in a wave like fashion (at a very small wavelength).

AustinGrove3B

more specifically 2.99792 x 10⁸. I think in the book they use this (more sig figs) than 3.0 x 10⁸

AustinGrove3B

The reading schedule is in the same outline as the homework problems. As a general rule, Dr. Lavelle tells us to read all the parts of the chapter that we are doing homework problems for.

AustinGrove3B

The energy would be enough to break the electron away from its atom, but it wouldnt be ejected away from it. So essentially it broke the electron's attraction to the atom but it is still there;.

AustinGrove3B

I believe the Sapling Learning is optional. I think it gives you access to an online textbook and has some tutorials to help you with chemistry. But I am pretty sure that you do not have to do any mandatory assignments for the class on it

AustinGrove3B

Everything is definitely given!! On test 1, you will see a big list of the formulas (I beleive that is actually the same formula sheet we will have on midterm/final if you wanted to see what was on it). I personally didnt even think the formula sheet was really needed for test 1. Professor Lavelle i...

AustinGrove3B

The question is confusing because the "extent of the change" is a really weird way of saying the slope of the graph. It wants you to see what would happen to the slope of the wave when freq decreases (wavelength increases) and therefore slope decreases (less steep). Its just a poorly worde...

AustinGrove3B

Essentially, they are important because they are the names of the major groups of spectral lines that Hydrogen gives off. The Balmer series is in the visible region of light, and the Lyman series is in the UV region of light. There are also other regions, such as the Pachen series in IR light, but t...

AustinGrove3B

Find the weight of 1 mole of water. Remember each mole of a substance contains exactly 6.022*10^23 molecules of that substance. Therefore the weight of a mole of water divided by 6.022*10^23 would equal the weight of 1 water molecule.

AustinGrove3B

You are correct that there are 9 Gallium molecules on the left. You do not know how many Astatine molecules you need to balance it. The simple way to do it is 210g mol / 70g mol =3. So each Astatine molecule will be 3 times as massive as each Gallium atom. Since there are 9 Gallium atoms, 3 Astatine...

AustinGrove3B

TA said pen is easier to read, but there is no requirement.

AustinGrove3B

TA told me that Dr. Lavelle actually meant to say he highly recommends doing the topics. They arent graded, but you are encouraged to do them.

AustinGrove3B

He wants you to pick any 7 relevant questions to complete for your homework for that week, which you will usually turn in to your discussion section. In the back of the syllabus and in the chapter outlines, Dr. Lavelle gives you a bunch of relevant problems that you could chose from.

AustinGrove3B

The solutions manual has the answers to all the odd number questions in the book, which are also located in the back of the textbook. However, in the solutions manual, Dr. Lavelle explains how to get each answer and includes his work (which is definitely not in the back of the book). Its a good purc...

AustinGrove3B

Using g mol^ -1 can sometimes make your math a lot cleaner to look at, compared to writing it as ___ g / ___mol. If you divide g mol^-1 by another g mol^-1, it avoids having to write fractions inside of a fraction. Technically, doing that would be correct, but it would be really hard to interpret.

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