CHEMISTRY COMMUNITY

Sharon Rodriguez 3H

Will we have to know how to identify whether an amphoteric salt given is more acidic, basic, or neutral? This requires using the ionization constants but I am unsure if we need to know how to calculate this.

Sharon Rodriguez 3H

What are some important/common electron withdrawing groups that we should look out for? Also could somebody further explain differences between electron withdrawing groups and electron donating groups? Thanks!

Sharon Rodriguez 3H

This will likely be information we need to know for the final. If questions do not directly ask about it, the concepts themselves will help regardless!

Sharon Rodriguez 3H

An acid will be stronger if it can easily lose hydrogen to a base. The CH3 in acetic acid donates electrons which makes the O-H bond stronger due to electronegativity therefore the H is harder to remove, which isn't what we want. This makes formic acid the stronger acid. Basically CH3 is electron do...

Sharon Rodriguez 3H

Amphoteric compunds can react with both acids or bases. The most common amphoteric substance is water so that is always good to know. There are 5 amphoteric elements which are Be, Al, Zn, Sn, and Pb. The oxides and hydroxides of those elements are amphoteric compounds. Hope this helps!

Sharon Rodriguez 3H

Yes, you should be aware of what complexes are as we discussed it for a portion of lecture. Things such as chelates and naming coordination compounds involve comlpexes. Remember that transition metal cations form complexes.

Sharon Rodriguez 3H

Since they are ligands, the lone pairs must be bonded to the central metal ion and the ligands act as Lewis bases while the central atom acts as the Lewis acid. From there, the number of lone pairs determines if it is a polydentate (more than 1 lone pair).

Sharon Rodriguez 3H

Unidentates have only one lone pairs but anything with more than one will be considered a polydentate such as a bidentate ligands which have two lone pairs. The lone pairs can all bond to the central metal ion.

Sharon Rodriguez 3H

Both water and salt are produced when strong acids and strong bases react. So for a strong acid + weak base, water is not usually formed since weak bases are not typically hydroxides. A weak acid + strong base the result is basic. A weak acid + weak base depends on the relative strength of the react...

Sharon Rodriguez 3H

I would say that just to be safe, we should specifically point out that OH- is the Bronsted base and Na+ is a spectator ion.

Sharon Rodriguez 3H

The majority of the time it is true that if a molecule has lone pairs, it will be polar. There are cases, like stated above, where molecules have lone pairs but are nonpolar. Remember to keep in mind the molecular geometry and dipole moments when considering this, there will always be exceptions so ...

Sharon Rodriguez 3H

How would you know if the pi bonds of a molecule are perpendicular to each other vs. parallel? In the case of H2CCCH2, the C=C pi bonds are parallel to each other but in H2CCCH2 the C=C pi bonds are parallel. Would we have to know this for test 2?

Sharon Rodriguez 3H

Everything that was not covered on the midterm so dipole moments, intermolecular forces (LDF, dipole-induced-dipole, induced-dipole-induced-dipole, hydrogen bonds, ion-dipole, ion-ion), molecular geometry so VSEPR, identifying polar and nonpolar molecules, types of bonds (sigma and pi). The cutoff w...

Sharon Rodriguez 3H

Adding on to what was said above, dipole-induced-dipoles aka london dispersion forces are temporary and depend of the number of electrons in an atom (it's polarizability) and typically, larger molecules are more polarizable. Nonpolar molecules with more number of e- have more LDF than polar molecule...

Sharon Rodriguez 3H

How do lone pairs on the central atom affect the dipole moments and polarity of the molecule? Do lone pairs have their own dipole moment and how would you determine where the dipole moment would point towards? Like for ammonia, :NH3, I have seen the dipole for N's lone pair to point away from N, why...

Sharon Rodriguez 3H

How do you know go about distinguishing what type of forces molecules have when interacting? How do you guys find it best to remember them, any tips? I tend to get confused between all the dipole forces. Thanks!

Sharon Rodriguez 3H

haileyramsey-1c wrote:Pi bonds are bonds formed by side by side overlap of two p orbitals. Sigma bonds are two electrons in a cylindrically symmetrical cloud between two atoms. Pi bonds occur in p orbitals and sigma bonds occur in s orbitals.

Are d-orbitals ever relevant in these situations?

Sharon Rodriguez 3H

What would be some relevant biological and inorganic examples of intermolecular forces and hydrogen bonding that we should probably know?

Sharon Rodriguez 3H

Apart from Nitrogen, what other elements that can break the octect rule due to free radicals should we watch out for and is there how do you remember it?

Sharon Rodriguez 3H

In nitrogen monoxide, NO, the radical can be assigned to both the nitrogen and the oxygen, right? It would depend on what the question asks but if asked for the "most stable" would you put the radical on oxygen since it is more electronegative? Also, is this considered resonance (the radic...

Sharon Rodriguez 3H

How would you find the lowest/highest frequency that will cause photoelectric emission if you are given the work function? From what I understand, the kinetic energy in both cases would be 0, leaving the workfunction = hc/lambda, is this correct?

Sharon Rodriguez 3H

Elements that are period 3 and beyond in the periodic table have access to the d-orbitals, which can fill up to 10 extra valence electrons. One example of this is SF6, where sulfur has 6 bonds to each fluorine atom and thus has 12 valence electrons. Some elements, such as B and Al can have incomple...

Sharon Rodriguez 3H

This really clarified it for me, thank you!

Sharon Rodriguez 3H

The 4s orbitals have a lower energy than the 3d orbitals, so the 4s orbitals are filled first. However, Lavelle has said to write 3d first. Even though 4s is lower in energy, is this where valence electrons would reside? I was under the impression by things I have read that valence e- consisted of ...

Sharon Rodriguez 3H

I understand why energy is required when removing an electron for ionization energy, however I am having trouble understanding why energy is generally released when adding an electron. Could somebody explain this?

Sharon Rodriguez 3H

They did mention 18 once but I wasn't sure as I have heard other things but yes this helped thank you!

Sharon Rodriguez 3H

When drawing out a Lewis structure with a central molecule that is an exception to the octect rule, is it likely that most of the time you will have to expand the octect? What is the max amount of electrons that an expanded octect can hold?

Sharon Rodriguez 3H

If there is a radical, would it still be possible to have resonance? How would the electron move in that case?

Sharon Rodriguez 3H

What is the difference between a resonance hybrid and resonsance structure?

Sharon Rodriguez 3H

How is the dissociation energy obtained?

Sharon Rodriguez 3H

Everything before interactions between ions and molecules is fair game. I believe a larger portion of the midterm will consist ofquantum.

Sharon Rodriguez 3H

The greater the polarizing power of the cation or the polarizability on an anion is, then the percentage of covalent characters will also be greater. If the cation is smaller, there is a greater polarizing power so there will be more covalent characters. Similarly, the larger an anion is means great...

Sharon Rodriguez 3H

Is VSEPR going to be covered in the midterm? Especially now that classes were cancelled and we won't get to go over today's material.

Sharon Rodriguez 3H

Why does 3d^10 have less energy than 4s^2? Could somebody explain the "switch" in energies that occurs in this area of electron configurations?

Sharon Rodriguez 3H

Could somebody explain what it means when electrons involved in resonance are delocalized?

Sharon Rodriguez 3H

A nodal plane is a plane where the probabilty of finding an electron is zero. The s-orbitals do not have one due to the spherical shape, there are no angular nodes possible. Any s-orbital has an angular momentum number, l, of 0.

Sharon Rodriguez 3H

I understand how to get the other quantum numbers however the spin state seems very conceptual. Are we ever going to be expected to figure out the spin state and if so, how would you go about doing that?

Sharon Rodriguez 3H

The speed of light will always be a constant and is labeled in equations as the variable "c". It is somewhere around 3.0 X 10^8 m/s. On exams, make sure to use the exact number for the speed of light that is given to you on the equation sheet of the exam. This will help you with getting t...

Sharon Rodriguez 3H

When a problem is asking for the velocity of the photoelectron produced, assuming the work function and wavelength are given, how would you go about finding the solution? The wording of problems is confusing at times to me as they don't explicity ask for something or the steps to solve it involve us...

Sharon Rodriguez 3H

Doing practice problems and lessons on Khan Academy has helped me so far! I also find that explaining concepts to others or having others explain to me, whether it be here or in person, really helps me to truly understand the concepts. Discussing each other's confusion and seeing things from another...

Sharon Rodriguez 3H

I believe this is the simplest way to find the atomic radius without having to do any calculations.

Sharon Rodriguez 3H

This question is asking you to calculate the wavelength of each particle (proton & neutron) when travelling at 2.75 x10^5 m.s^-1 and report the difference as a percentage of wavelength of the neutron. First off, you would use λ=h/mv as we are trying to find the wavelength. First, use this equati...

Sharon Rodriguez 3H

HΨ=EΨ is the time-independent Schrodinger's equation which considers the electron as a standing wave. This is a mathematical model stating is that the sum of the wavefunction's kinetic energy and potential energy (aka the Hamiltonian operator) is equal to the wavefunction's total energy. It is an ei...

Sharon Rodriguez 3H

Yes, atomic spectroscopy is the study of electromagnetic radiation emitted and absorbed by atoms. When an atom absorbs energy, it's electrons will jump to a higher energy level and if an atom emits energy then the electrons will jump down to a lower energy level. These so called jumps have a certain...

Sharon Rodriguez 3H

You know the energy of the photon (E) and we know E=hv with h being Planck's constant (6.626x10^-34 J.s) so the only unknown in this equation would be v, the frequency. Rearange the equation to solve for v which would be v=E/h. After plugging in the values and finding the answer, you can find the wa...

Sharon Rodriguez 3H

From my understanding, the Rydberg equation is to determine the wavelengths of the line in the hydrogen emission spectrum, therefore this equation only applies to hydrogen atoms, not all elements (that is beyond what we need to know). The Balmer series applies when the lowest energy level possible o...

Sharon Rodriguez 3H

Whenever there is an exponent of -1, it is equivalent to (in this case) 1/s simply meaning per second. The same thing goes for things such as g.mol^-1 which is equivalent to g/mol.

Sharon Rodriguez 3H

That makes sense, I forget to simplify the ratios so I'll make sure to catch that now. Also, appreciate that alternate way of solving for limiting reactants and the location in the textbook, thank you!

Sharon Rodriguez 3H

It is likely impossible to have an absoulte exact 1:1 ratio as one reactant will always be completely used and the other may have a minute amount of excess. I would assume that such a small amount is considered insignificant so in those cases you can just see it as being an equal reaction with no li...

Sharon Rodriguez 3H

I compared the experimental mole ratios of NH3 and O2 to the ratios of the stoichiometric coefficients given in the problem. As you probably calculated: 21.4 g NH3 = 1.2566 mol NH3 42.5 g O2 = 1.328125 mol O2 In the reactant side of the given chemical equation, the ratio of NH3: O2 = 4:5. Based on ...

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