CHEMISTRY COMMUNITY

AprilPaz

What are some examples of polydentate ligands besides EDTA ? How can you tell from the formula if it is a polydentate ligand?

AprilPaz

pKa and pKb is the measure of the strength of the acid or base. pH is the measure of the concentration of h+ protons.

AprilPaz

Resonance is the delocalization of electrons. Thus, if you have a structure with resonance, delocalization is occurring.

AprilPaz

What do we need to know about myoglobin and hemoglobin for the final exam?

AprilPaz

When calculating the frequency of energy absorbed or emitted from changing levels of energy, which equations will be used in the problem?

AprilPaz

How can you tell how many hydrogen bonding sites there are?

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The difference in electronegativities dictates the size of the dipole moment.

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Unhybridized orbital because electron repulsion causes too much energy cost for an electron.

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If the complex is negatively charged, -ate is added to the TM.

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A promotion occurs during hybridization when an atom needs to form a certain amount of bonds. For instance, carbon needs to bond 4 times. During hybiridzation we promote on electron in order to occupy space in an extra orbital.

AprilPaz

Since it has a negative charge, cobalt would turn to -ate.

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If the dipoles in the molecule do not cancel out, then the molecule will be polar.

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Transplatin is not a chemotherapy drug because it cannot form a coordination compound with the DNA. Since it has its Cls on opposite sides, it cannot align with the DNA and bond.

AprilPaz

Cisplatin stops cell division because they have their Cls on the same side of cisplatin. When cisplatin is administered, the Nitrogens along the guanine will displace the Cls on the Cisplatin which causes the bond to be blocked when it is being replicated.

AprilPaz

London forces is dependent on the size of the molecule. Thus, just look for the larger molar mass.

AprilPaz

How does an atom having preference affect the molecular shape ? Dr. Lavelle brought up several times how Fluorine will change the dynamic since it has preference.

AprilPaz

It would be helpful to be familiar with all names not just the most common.

AprilPaz

Dr. Lavelle said as long as you draw one structure of the resonance molecule then you should be fine. We are looking at the molecular geometry of one resonance structure. Since a resonance structure is a blend of all structures, their molecular geometries should be the same across all resonance stru...

AprilPaz

When trying to find out if a molecule is polar or non-polar, write all the dipole moments and see if they cancel out. If the dipole moments do not cancel out, then the molecule is polar. If the dipole moments do cancel out, then the molecule is non-polar. Since SF4 has 4 bonds and one lone pair, the...

AprilPaz

When you add two electrons to the element sulfur, the ground state configuration leads you to Ar. The fact that Ar happens to be a noble gas is why the answer was abbreviated.

AprilPaz

Why would C4H9OH have a higher melting point than C2H5OC2H5?

AprilPaz

Polarizability depends on size and charge. No assumptions can be made since each element has a different amount of electrons. The more electrons the farther they are away which allows the nucleus to not have a strong hold on them. Thus, the more electrons the easier it is to have a dipole moment bec...

AprilPaz

Yes, electronegativity is how much an atom can attract electrons. A dipole moment is when one atom is strongly attracting the electrons more than the other. Thus, the dipole moment is centered from electronegativity.

AprilPaz

As an atom increases, they have more electrons which causes more electron repulsion.

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Lone pairs count as electron densities.

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The question will specify if it wants it or not.

AprilPaz

Will hybridization be on the midterm ?

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Isoelectronic means atoms and ions with the same number of electrons.

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The purpose of calculating formal charge is to allow you to check if your lewis structure has the lowest energy possible. The least amount of formal charges you have the better.

AprilPaz

Yes. Since all the elements in that column have the same number of valance electrons they will follow the same exception.

AprilPaz

Drawing lewis structures is really just trial and error. If you draw a full lewis structure and realize you have too many electrons surrounding the elements, then a double bond has to be used. If you still have too many electrons after you have done a double bond, then a triple bond needs to be used.

AprilPaz

Removing the second electron will always be more difficult than the first because once one electron is removed it makes the net charge positive. Once the net charge is positive, the element will hold on to it's electrons more tightly which in turns means it is harder to remove a second.

AprilPaz

Resonance is more stable since it has the ability to have different arrangement of electrons. Resonance allows multiple bond characters which lowers the energy of the arrangement of atoms.

AprilPaz

How do we determine the amount of valance electrons the D-block elements have ?

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How would I represent an anion in a lewis structure?

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What are Pi bonds? How do they contribute to a lewis structure?

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Delocalized means that the electrons are not associated with one atom. Instead they can move around.

AprilPaz

The significance of this example was resonance because we are visually seeing how different arrangements of electrons can be written in several ways. The importance of bond length in this example is that the average of the atom is a hybrid.

AprilPaz

Resonance is determined when a lewis structure has multiple bonds in different locations that are the same as each other.

AprilPaz

What is the importance of the photons and electrons untangling and what effect does it have on Heisenberg's Indeterminacy Equation?

AprilPaz

The periodic table Prof. Lavelle provided is good.

AprilPaz

In problems, how do we know when to use these two concepts?

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Why are Cr and Cu considered exceptions?

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I use khan academy as another resource when I feel like I did not grasp the concept fully. It provides extra support and practice problems !

AprilPaz

Always balance the elements that stand alone VS. balancing the elements that have several others attached to them. For example, Li3N (s) + H2 (g) -> LiNH2 (s) + LiH (s) I would only work with balancing H2 and LiH. Li3N (s) + 2H2 (g) -> LiNH2 (s) + 2LiH (s).

AprilPaz

Doing the problem is up to you and what your preference is. The process is still the same whether you rearrange it immediately or not.

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The Paschen and Brackett series use lower energy, and they are on the lower scale of infrared region.

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When light is emitted, an electron goes from high orbit to low orbit and the electron is absorbed when going from low orbit to high orbit. The difference of energy between two orbitals determines the energy and frequency of light emitted. Thus, different frequencies equate to different wavelengths, ...

AprilPaz

What is the unit for 1 angstrom?

AprilPaz

Whether you are adding, subtracting, multiplying, or dividing, the ground rule is to have the same amount of sig figs as the value with the lowest amount of sig figs.

AprilPaz

I begin by balancing the element that shows up the least then I move on to the next. The posts above sum up the process pretty well though!

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