CHEMISTRY COMMUNITY

Amanda Ung 4D

I'm not 100% sure about this, but while it's true that the conjugates of weak bases/acids are stronger, they are not necessarily THAT strong. In essence, the conjugate of a weak base or acid will not always result in what we consider a strong acid/base.

Amanda Ung 4D

I think the only ones we need to know are iron and copper. In anionic complexes, they become ferrate and cuprate, respectively. You can easily remember this by looking at their atomic symbols: Fe (iron) and Cu (copper).

Amanda Ung 4D

[Pt(en)2Cl2]Cl2 is a coordination compound and coordination compounds are neutral. Because chloride has a charge of -1 and there are 2 in the compound, we can conclude that the complex ion [Pt(en)2Cl2] has an overall charge of +2. The oxidation number of platinum would be +4 because, as previously s...

Amanda Ung 4D

Coordination compounds are neutral. In this case, it seems the complex ion would probably have a charge of -4 because potassium ions have a charge of +1 and there are 4 in this compound (K4). The oxidation number of iron, however, is +2 because cyanide has a charge of -1 and there are 6. If you're l...

Amanda Ung 4D

The molecule is polar. The lone pair pushes the bonded atoms down into the see saw shape thus making the overall dipole moment point downward in the direction of all bonded atoms.

Amanda Ung 4D

What exactly is hybridization and why are hybrid orbitals significant?

Amanda Ung 4D

Why are F2 and Cl2 gases at room temp vs. Br2 and I2 which are solids at room temp?

Amanda Ung 4D

It was definitely covered after the midterm though we haven't done much practice with it in class/discussion; however, we also haven't been given much time to as well. I would understand its significance and how to calculate Ep just in case because not much practice was done with Rydberg's equation ...

Amanda Ung 4D

Ionic character of a bond will increase with an increased difference in electronegativity

Amanda Ung 4D

To clarify, hydrogen bonds being intermolecular forces strengthen covalent bonds and thus increase the boiling point of certain molecules? What notable influences do hydrogen bonds have on ionic bonds?

Amanda Ung 4D

The electron-electron repulsion between the lone pairs and the bonded atoms pushes the bonded atoms farther away thus lessening the bond angle.

Amanda Ung 4D

It would be a good idea to know how to draw the lewis structures (obviously) and just generally know how to draw the 3D versions; however, I recall Dr. Lavelle saying we won't need to draw them on the test.

Amanda Ung 4D

Can someone elaborate/clarify what "lone pairs do not influence molecular shape but only atom positions are used to name the shape" means? I thought lone pairs did have some part in influencing molecular shape such as in see-saw or bent. I might be misinterpreting this statement.

Amanda Ung 4D

There’s a bunch of shapes that we’ll eventually learn about so yes it does matter but we don’t need to worry about it now!

Amanda Ung 4D

It’s cumulative

Amanda Ung 4D

In terms of single/double/triple bonds, the strongest and shortest would be triple bonds and decreases in strength and increases in length with single bonds being the longest and weakest.

Amanda Ung 4D

VioletKo3F wrote:Does anyone know if we'll get the actual midterm back? Or is it only our grades?

We get the actual midterm back I think

Amanda Ung 4D

what about the ionization energy of nitrogen? Is It greater than oxygen? Yes because nitrogens subshells are completely half filled which is more stable than oxygen which has 1 pair and 2 lone electrons. The electron electron repulsion of oxygen’s orbital causes it to have a lower ionization energy...

Amanda Ung 4D

Yes higher electronegativity means higher attraction of electrons

Amanda Ung 4D

Avoid putting the negative charge on the central atom but try to make most of the formal charges equal 0!

Amanda Ung 4D

The central atom is typically the element with the lowest ionization energy. Hydrogen can never be the central atom

Amanda Ung 4D

The observed bond length is the distance between the nuclei of two bonded atoms. Its relevant to resonance structures because resonance structures depict the possible ways in which bonds can orient themselves; however, resonance really is a blending of structures with the same arrangement of atoms b...

Amanda Ung 4D

Longer bonds are weaker (easily broken) and thus are more likely involved in reactions. These would be single bonds, and as you increase into double and triple bonds, they get stronger and shorter. Therefore, double bonds are shorter and stronger than single bonds and triple bonds are stronger and s...

Amanda Ung 4D

I think the question would be better phrased with ions causing large distortions rather than larger ions. Ions which cause large distortions have high polarizing power which makes an ionic bond have more covalent character. Covalent character implies less soluble in water as covalent compounds typic...

Amanda Ung 4D

Use lewis structures and put a bracket around it with the charge in the upper right hand corner

Amanda Ung 4D

We haven't learned anything about chemical bonds so I think it's safe to go with quantum world problems still.

Amanda Ung 4D

I don't think we have to know the exact measurements but a good thing to keep in mind is that in resonance structures, the actual molecule is a blend of all possible structures.

Amanda Ung 4D

This isn't a trend but I think a good exceptions to remember when doing electron configuration are chromium, copper, molybdenum and silver such that a half or full d orbital is more stable than being partially filled, so an electron from the 4s/5s orbitals rise to a 3d/4d orbital.

Amanda Ung 4D

A negative electron affinity signifies a release of energy (exothermic reaction) and a positive electron affinity means more energy is needed than gained when adding the electron.

Amanda Ung 4D

Ionization energy is always positive because you have to add energy to remove an electron (an endothermic process).

Amanda Ung 4D

Yes. Due to their lower ionization energies, the s block elements are able to give up electrons more easily thus forming cations which makes them more reactive.

Amanda Ung 4D

There is an equation sheet on Dr. Lavelle's website. If there aren't any on that sheet that we learned in class, it's a good idea to take note of them and memorize/get a good understanding of the equation because it's probably important.

Amanda Ung 4D

On that note, does anyone know which topics will be covered which weeks? I expected to see weeks on the syllabus next to each new topic, but didn't notice anything like that. I didn't see a calendar or anything. I think there should be a week or at least a couple days to review everything (which is...

Amanda Ung 4D

I think it's good to memorize the important equations like E=hv or c = lambda(v) because they are used together a lot. We should be learning more that are just good to memorize even though they might be provided because it will show you have an understanding of the concept and you can save time on t...

Amanda Ung 4D

Yep. Dr. Lavelle was using this as an example to disprove something in class!

Amanda Ung 4D

n-levels are energy levels that electrons can jump to are fall from. Jumping energy levels requires energy to be put into the electron (exciting it) and electrons that fall from higher energy levels to lower emit energy to get back to their ground state.

Amanda Ung 4D

E = hv --> E is the energy of the photon and you get it by multiplying Planck's constant (h) and the frequency (v)

Amanda Ung 4D

cycle per second (s-1)

Amanda Ung 4D

Yes I think we always get an equation sheet

Amanda Ung 4D

Wavelength is measured in meters but always keep in mind the conversions! Typically the problems that I've seen for wavelength call for answers in nanometers.

Amanda Ung 4D

frequency and wavelength are inversely related

Amanda Ung 4D

Sounds good! Remember to consider light as photons, or packets of energy where one photon interacts with one electron. High intensity light with long wavelengths and low frequency wouldn't be able to eject electrons; therefore, it really depends on the energy of the photon and not the intensity of t...

Amanda Ung 4D

There would be 3 sigfigs in 7.00 x 10^2. Despite it being 700, the notation matters. Therefore if your answer was 700 but you needed to make it 2 sigfigs, you would put your answer as 7.00x10^2.

Amanda Ung 4D

curry 1E wrote:Can someone explain what Angstroms are? I was confused on the test on this question.

Angstrom conversions are given on the test. It's significant to know because bond lengths are typically measured in Angstroms.

Amanda Ung 4D

pauline 1L wrote:Does anyone know where and when our grades for this class will be updated?

I believe our TAs will be handing them back during the next discussion!

Amanda Ung 4D

I memorized them really fast using quizlet! My old chem teacher recommended pairing "-ate" and "-ic" and thinking of it as "ate it" and "-ite" and "-ous" as "bronch-itis".

Amanda Ung 4D

I think you should memorize them all just in case. It's not too difficult as you should probably memorize them for upcoming courses and labs as well

Amanda Ung 4D

You can do either. Pencil is probably recommended as pen can get messy if you make mistakes

Amanda Ung 4D

Test is in your upcoming discussion section! Good luck studying :)

Amanda Ung 4D

You can technically get Fahrenheit from Kelvin too through Celsius, but it's more common to see Celsius and Kelvin in chemistry. As said by the person above, they're linked by magnitude (Kelvin is Celsius + 273.15).

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