CHEMISTRY COMMUNITY

Ryan Juncker 3D

They are correct above that chelating ligands effect the shape of a coordination compound. Yes, we use the coordination number of the central metal to determine the shape; but a bidentate or tridentate ligand would raise the coordination compound by 2 or 3 respectively.

Ryan Juncker 3D

Pi bonds cannot rotate and I don't believe with D. Lavelle or the book ever mentioned rotating a bond to break it. I believe it would have to be by forces that break any other kind of double bond, although I don't think this is something we necessarily need to know for 14A.

Ryan Juncker 3D

Yes, this is because a Bronsted acid gives off a proton; however, a Lewis acid (electron pair receptor) does not need to have a hydrogen to be considered acidic.

Ryan Juncker 3D

The biggest thing we need to know for chem 14A I believe is that a higher KA is a stronger acid, while a lower pKA is a stronger acid.

Ryan Juncker 3D

An amphoteric compound react with an acid or a base; an amphiprotic compound can give off a proton or receive a proton.

Ryan Juncker 3D

I was going back and doing Dino nuggets (the midterm review) number 8b and think I did the right conversion and formula but have gotten the wring answer multiple times. Can anyone help me out on this?

Ryan Juncker 3D

The transition metals are all the d-block elements (groups 3-12).

Ryan Juncker 3D

I am pretty sure that in lecture Dr. Lavelle stated that we will only be responsible for calculating the pH of strong acids and strong bases and that we learn how to calculate weak acids and bases at the beginning of 14B. Can someone confirm this?

Ryan Juncker 3D

Although it would probably be best to ask a TA or Dr. Lavelle to know for sure about test material I would guess that we should know both how to go from the chemical equation to the name and vice versa. Especially given that the midterm was more complex than Tests 1 or 2 we should probably be able t...

Ryan Juncker 3D

When the overall charge of the molecule is negative, you change the ending of the central metal to -ate. The ligands still use their normal prefixes and suffixes.

Ryan Juncker 3D

The transition metals in the d-block are more electronegative than the metals in other groups. I'm not sure that this is necessarily true. While they do behave differently I believe that Fluorine and other elements nearing the top right of the periodic table (minus group 18) are more electronegativ...

Ryan Juncker 3D

According to Dr. Lavelle's lecture and the textbook, a radical is an atom that has an unpaired electron in a lone pair (shown by one dot in the Lewis structure). Radicals are very unstable and reactive due to this electron wanting to be paired.

Ryan Juncker 3D

As we discuss naming larger molecules are we going to be expected to also be able to draw correct Lewis structures based off these names or will we also be given the chemical formula showing which atoms are bonded to one another?

Ryan Juncker 3D

Lewis acids and bases are the same as regular acids and bases and can be defined using mostly the pH scale. The difference is in whether you are using the Lewis definition or the Bronsted definition of acids and bases. In the Lewis definition acids are electron acceptors; however, in the Bronsted de...

Ryan Juncker 3D

Do we need to know the difference between Cis- and Trans- bonds for test 2 this week? And if so can someone please elaborate on it.

Ryan Juncker 3D

How do you tell if a molecule is elongated or spherical? Is it simply by looking at the Lewis structure or is there a better way?

Ryan Juncker 3D

Polarizability of an atom can effect the strength of IMF's by making the dipole moments stronger and size of an atom, in particular the number of electrons has an effect on London forces (more electrons meaning stronger London forces).

Ryan Juncker 3D

Shape will effect biological activity mostly for proteins and enzymes. Dr. Lavelle used it as an example in class to show us why the concept was important but I don't think it will be important to know anything about for the test.

Ryan Juncker 3D

Molecules do not always have dipoles. A dipole moment only occurs in polar bonds or if an instantaneous dipole induces an instantaneous dipole in another atom. You can tell if a molecule is polar first by determining if its bonds are polar and then looking at whether or not they cancel out because o...

Ryan Juncker 3D

In a perfectly symmetrical trigonal bipyramidal molecule do the dipole moments all cancel like they do in a symmetrical tetrahedral or can these molecules still be polar?

Ryan Juncker 3D

Is there a way to be able to tell for sure whether a bond (not molecule) is polar or non-polar without being able to see the electronegativity of both atoms?

Ryan Juncker 3D

Stronger bonds are shorter bonds. Triple bonds are shorter than double bonds which are shorter than single bonds. Also, bonds between smaller elements tend to be slightly stronger.

Ryan Juncker 3D

Hey guys, unfortunately I had to miss friday lecture this week. I got a copy of the notes from a friend but I am just wondering if there was any specific points you guys think are very important I should review on my own or if there were any important announcements about the midterm or test 2? Thank...

Ryan Juncker 3D

Yes, even if the formal charge or C,N,O or F is not zero they will follow the octet rule because they are period 2 elements and do not have a d shell to fill up with electrons.

Ryan Juncker 3D

Larger anions are more polarizable and ionic radius follows the same trend as atomic. This means that the most polarizable atoms will be in the lower left corner. Smaller cations with a higher charge are atoms with the most polarizing power and this would mean that the atoms near the top right would...

Ryan Juncker 3D

Just to clarify will Test 2 be on only the information between the midterm and the test or will it also be accumulative and just shorter?

Ryan Juncker 3D

An induced dipole is created by a non-polar molecule coming into contact with a polar molecule. The charged polar molecule repels the electrons of the non-polar molecule, causing the electrons to shift creating a charge.

Ryan Juncker 3D

Isabella Dal Porto 1I wrote:So does the midterm cover the fundamentals up until the quantum world or will it include chemical bonds also?

Dr. Lavelle said the midterm will include chemical bonding information all the way through Fridays lecture (expect for the last slide he showed).

Ryan Juncker 3D

Can someone please elaborate on the definition and purpose of electron affinity for me? Thanks

Ryan Juncker 3D

Atomic radius increases down a group and decreases left to right across a period.

Ryan Juncker 3D

Resonance structures are bonds in which the Lewis structure contains one or more double bond. These molecules have resonance if the double bond could be placed on more than one bond in the Lewis Structure. In reality, the bond is actually continually shifting and both or all bond lengths involved in...

Ryan Juncker 3D

Electrons further away from the nucleus are easier to remove because 1) they are farther away from the positively charged nucleus so the attraction isn't as strong and 2) they are shielded by the inner electrons also lessening the chemical attraction.

Ryan Juncker 3D

The test banks as they mentioned above seem like a good idea and but I haven't checked them out for myself. I would recommend going to the review sessions Dr. Lavelle will be putting on because they will probably be the most related to the tests themselves.

Ryan Juncker 3D

I'm not sure how many questions it will be or the exact information but I'm guessing it will be heavily based on "The Quantum World" unit with some review questions from the "Review of Chemical and Physical Principals" unit. I would also think it's reasonable to guess that the qu...

Ryan Juncker 3D

Obtaining the formal charge of zero is generally more important because it provides you with a more stable structure. I believe what Dr. Lavelle said is for example in PCl5 Phosphorus will expand its valence shell to 10 electrons.

Ryan Juncker 3D

Debora Fernandez Clemente_ 4H wrote:why is the electronic configuration of Ag [Kr] 5s^1 4d^10 instead of [Kr] 5s^2 4d^9?

In this case having the 4d shell completely filled and the 5s shell half filled is actually more stable than following the usual pattern of 5s^2 4d^9.

Ryan Juncker 3D

Can someone please elaborate on destructive interference for me?

Ryan Juncker 3D

The best tip Dr. Lavelle gave in class that's been helping me is to balance the element that occurs in the most molecules in the equation first then work down to the ones that don't show up as much. This way you don't have to go back and make as many changes if balancing one atom affects another.

Ryan Juncker 3D

Personally, I like to think of electron spin separately from thinking of the wave like properties. It just makes more sense in my head to think of that part along with the particle properties or with the electron configuration. Hope that helps.

Ryan Juncker 3D

I think the textbook is very well-written for really breaking down topics that we go over in class. Especially if we went over something in class quickly that I didn't quite grasp I think its a great way to clear some things up. Also, the "self-check" problems are a great way to confirm wh...

Ryan Juncker 3D

We will only have to know the first row of d-block along with s and p.

Ryan Juncker 3D

What does Dr. Lavelle mean in lecture when he states that all matter has wavelike properties but it is only noticed in moving objects with extremely small masses like electrons? Thanks

Ryan Juncker 3D

Kinetic energy does not change if light intensity increases because that will only increase the number of photons. There could be double the photons but because we now know that each specific photon interacts with a specific electron it only matters if that one photon meets the threshold energy to e...

Ryan Juncker 3D

The video modules along with each pre and post test are highly recommended to go with each section per the syllabus but none are required or have any affect on your final grade in the class.

Ryan Juncker 3D

I know the TA's are the ones to grade the tests so I believe they will be giving them back in discussion this week but I'm not positive on that.

Ryan Juncker 3D

I believe the way it was explained was that the original model of light was the wave model in which light always acted like a wave - bigger wave equals higher intensity. However, the results of the photoelectric experiment gave way to the photon model where light is seen more by the individual photo...

Ryan Juncker 3D

Test one is just the review sections. Make sure to check out the link that Dr. Lavelle sent out that takes you to the topic review.

Ryan Juncker 3D

We were told in discussion that all that really mattered on the tests was to get the right answer and we would be given credit; however, If we make a math error early on in the problem and carry that error through but complete the rest of the problem correctly we will be given partial credit. In tha...

Ryan Juncker 3D

There will always be multiples of the stoichiometric coefficients that you could come up with, or might end up with if you made a calculation error somewhere along the way, but the goal of balancing the equation is to get the lowest possible whole number coefficients. Because we are looking for the ...

Ryan Juncker 3D

It most likely depends on the specific problem, but we were told in discussion today that the general order would be to convert from grams to moles in order to work out the problem; then convert back from moles to grams to show your final answer. The example we used this on today was finding how muc...

Ryan Juncker 3D

Our TA told us today in discussion that for most questions at this point no credit will be taken away for not showing work as long as the answer is right. However, some questions on the test may tell you specifically to show all steps. He also of course highly recommended working out the steps for a...

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