CHEMISTRY COMMUNITY

AGulati_4A

Ka refers to the ionization constant, or the [H+] and [A-] divided by the [HA]. Therefore, in a reaction that may have acids such as H3PO4, the acids can dissociate thrice. In this case, the Ka1, the removal of the first hydrogen will be higher than Ka2 and so forth

AGulati_4A

WHy can option c), pyrimidine, form a chelating complex even though the N atoms are so far apart in them?

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Lewis structures = unpaired electrons, therefore, lewis acid = accepts electrons. And therefore Bronsted acid: donates proton

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Single = Sigma, Double = Sigma +Pi

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EDTA is a compound which can bind to heavy metals in the blood and exude them from the body before they can react with the DNA in our body and make it "unreadable"

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Among othrs you might want to know the acid reaction present in digestion and those that occur in filtration of fluids in the body. But these you shouldn't be concerned about as he is probably not going to test your biological knowledge as much as he is your chemical.

AGulati_4A

Because the intramolecular forces are extremely strong in the molecule. The dipole moment in the molecule most definitely shifts away from the hydrogen which pulls it towards the molecule and thus is harder to separate from it. It is a weak acid if it has a strong bond and vice versa

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a) IF the chlorines are apart from each other the molecule is non-polar as the dipole moments cancel each other --in any other case it would be polar
b) The largest dipole moment would occur in the molecule which ahs the chlorines closest to each other.

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An unhybridized orbital

AGulati_4A

I can't remember if we went over this in the lecture but compounds with pi bonds cannot rotate and thus cannot be more than monodentate?

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Tetrahedral is 109.5, Trigonal planar is 106-107 so bent would be a little lesser than the latter, being about 102-105 -- which is not something you necessarily need to know.

AGulati_4A

There would be a slight difference in the angle but this wouldn't be different enough to impact the molecular shape. This difference would be so small it would be negligible but if you are asking conceptually, there must be a difference.

AGulati_4A

All molecules have the LDF force. A molecule has a dipole-dipole interaction if it has a large difference in electronegativity -- which gives partial charges to each side of the molecule. Additionally, if the molecules have dipoles that do not cancel -- then they are a polar molecule. Further, if a ...

AGulati_4A

I think you mean for c) and yeah I thought they should be that way I think in this case they want you to assume the most unstable resonance structure. But you shouldn't worry about this, you won't encounter questions like this on the test -- and if you do, they probably will give you the lewis struc...

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Induced Dipole-dipole is usually stronger as chemical interactions between gas particles are usually weaker due to the larger distance between them

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I think it is because of the positioning of the Oxygen molecule, as it is more accessible to form a hydrogen bond in the Butanol than in the dimethyl ether

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covalent

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A polar structure has non-cancelling electronegativity vectors while a non-polar structure has cancelling ones.

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a lone pair in an electron that creates a large negative charge

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electron pairs

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H2CO3 and H3PO4, the compounds in the questions are the conjugate bases and the other would be the acid

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Because the electron pair in the resonance structures are delocalized -- which means that they are not bound to any certain atom. And since they are no bound to any atom -- bond lengths keep changing which results in each bond -- at some point in time -- having an average bond length which is equal ...

AGulati_4A

They are compounds that could have multiple variations for their structures, therefore -- these structures have delocalized electrons that make a changing structure

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If the compounds are very far apart on the periodic table then they are ionic, if they are close to each other they are covalent

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Br is a larger atom and has more electrons thus has a larger atomic radius -- because it has a lower effective nuclear charge. Therefore, the Br atom has lowerr electronegativity than the Cl atom

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the velocity of light is c -- a constant -- while frequency is variable depending on the wavelength

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The speed of electromagnetic radiation is a constant -- c. This is not changed by wavelength or frequency. If you are referring to the multiple-choice from Lyndon's workshop, the answer choice was a trick.

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E= P*C is probably most likely not used in calculations. I think when it could be important is in the derivation of the De Broglie wave equation, which converts the P into mv and C into (lambda)(frequency) in order to find the De Broglie equation

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Keep in mind the prefixes that were highlighted in the lectures, M or mega refers to 10^6 so one MHz would just be 10^6 Hz

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If it is an anion and a cation then it is an ionic bond. KCl is ionic since K has a +1 charge while Cl- has a 1- charge. On the other hand, something like CH4 is a covalent bond since the C and the H both have a positive charge (4+ for the C and 1+ for the H)

AGulati_4A

The N is the central atom. The two H from the NH2 are each attached to the N. Further, both the Carbons are single bonded to the central N atom. The COOH molecule -- which, if you know from organic chem -- is a carboxylic acid which has one O double bonded to the Carbon and the other Oxygen single b...

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The De Broglie equation requires you to calculate the momentum of a particle. In that calculation, you need the mass of the particle, which for a photon is non-existant. Therefore there is no way of using the De Broglie equation for photons

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The charge of a cation, in particular, can affect how the strong its polarizing power is. For example, a K+ ion has less polarizing power than an Mg2+ ion. Further, a K+ ion will have more polarizing power than a Rb+ ion since the K+ ion has a positive charge than can have a large distance of influn...

AGulati_4A

The e- config for K is [Ar]4s1 while for Sc^(2+) it is [Ar]3d1. This is because Sc normally is [Ar]3d1 4s2 but when you ionize this and take away 2 electrons you first have to ionize the 4s orbital and then, if necessary, the 3d orbital. This is because the 3d orbital becomes of less energy than the...

AGulati_4A

Only do that if they ask you to, they will specifically ask you to draw the resonance structures

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It is only used for electromagnetic radiation, E= 1/2 (m)(v)^2 is used for particles

AGulati_4A

You just need to know that it is a waveform equation and the sign used to represent electron position is psi (the trident) and (psi)^2 is the electron density in a region. You would also need to know the idea that, barring the s orbital, all other orbitals have suborbital -- which intersect at the m...

AGulati_4A

It is highly possible; I think the best way for you to learn is to 1. Learn how to write out ionic compounds 2. How to write out covalent formulas and 3. learn the names and charges of common polyatomic ions. For the more complicated molecules, you probably will be given the formulas.

AGulati_4A

You have to draw the valence electron configuration diagrams for this. Since N has 3 electrons in its p shell, the electrons are each in different suborbitals -- and have a parallel spin (the px, py, and pz orbitals). And Oxygen actually has 4 electrons in its 2p shell, so one of the sub-orbitals ha...

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AGulati_4A

the higher the polarity, the more unequal the sharing of electrons would be, and the higher the ability of the two atoms to ionize and therefore the higher the ionicity.

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electronegativity is a derived value, therefore, it is not something that is experimentally measured -- so you would be right in saying it is a value compared to others.

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Electronegativity is an experimental value while electron affinity is a naturally present value. Further, electronegativity is the measure of an element's ability to pull electrons towards itself when bonding while electronegativity refers to the ability of an element to gain electrons in its ionize...

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Just add the electronegativities to each atom on the compound, the vector lines point to those atoms that are relatively electronegative

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I don't think so if we don't learn about it in lecture we are most likely not going to see it

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It isn't really explained why it is but you just have to know. I think in order to understand that you have to go further into chemistry. There are no clues about it either, with regards to the idea of orbitals.

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I don't think we have to calculate the dipole moment. This is a topic we learn in chem 14b

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An electron is not in itself distorted. If the effective nuclear charge of the atom that the electron is part of is relatively low and the ionization energy of the atom that pulls the electron towards is relatively high -- then the electron is highly polarizable and thus distorted

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When one or both of the atom is/ are part of a compound that contains a dipole. This means that they have a relatively positive or negative change and can result in a dipole

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Radicals are just compounds or molecules that are not in their most stable form. This means that they do not have all of their valence electrons paired yet and thus are unstable. A good example of this is CH3, which is produced by incomplete combustion. This molecule of CH3, unlike methane (ch4), ha...

AGulati_4A

The d orbital is not part of the valence shell for the most part because it is never the first one ionized -- when you ionize elements. This is because before you fill the d orbital in the electron configuration of an element, you have to fill the s orbital. This means that for example if you are wr...

AGulati_4A

The anions electrons, when it intially reacts with a cation, are pulled towards the cation -- forming a temporary dipole in the anion. The ability of a cation to pull the anion's electronas towards it refers to the polarization power while the extent to which the electrons are pulled refer to the po...

AGulati_4A

This is extremely important as you want to classify the difference between the different orbitals between the bonds.

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Not necessarily, but Professor Lavell mentioned that he would prefer, for the sake of doing it in the future, you should start adopting it now.

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"Electron affinity increases as the number of valence electrons in a compound decrease". If you can remember this, you do not need to memorize the periodic trend

AGulati_4A

Delocalization of electrons essentially means that the electrons can disperse throughout the internuclear structure of the compound or molecule. in order to understand this you first have to let go of the conception that bonds are actual "lines" or "physical strucutres." Bonds ar...

AGulati_4A

Convert the value to Joules and then you can plug it in as a unit for Energy is the equation E=HV, where E is the energy, H is Planck's constant 9which will beon the formula sheet), and V is the wavelength -- which you can then find easily

AGulati_4A

No, i think professor Lavell said in class that this is omitted from the textbook. We don't need to know this its just there so that you can see it. I think he also said these are graduate level.

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Electrons, when energized, move up to certain energy levels in the atom. This means that they are in a certain distance away from the atom -- due to their specific energy. The position they are in, and where other electrons of the same energy are in, is classified as an orbital. This is all he means...

AGulati_4A

Just be careful though. He said this specificity is fine for the p orbital but he didn't recommend doing this for the d orbital as it can get complicated and we become more prone to making mistakes

AGulati_4A

Try to create a compilation of all the problem sets that have been discussed in class along with the ones in discussions. Try to complete that problem as though it were an exam, and learn all the concepts that you missed on that exam

AGulati_4A

It would increase the kinetic energy of the electron -- with what remains of the initial energy after accounting for the work function

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So when one says that electrons at a higher energy level have more energy, this means that they have more Kinetic energy -- or the energy of movement. conversely, when electrons are at lower energy levels -- they don't lose their energy, at lower energy levels they have more potential energy -- whic...

AGulati_4A

Amplitude is just how high and conversely how low the wave can go. Thinking about it in an analogical way, if you throw a ball, how high up you throw it doesn't really affect how far it goes in the sideways direction. in the same manner, how high up the amplitude of a wave goes doesn't really reflec...

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Photons are considered a subset of electromagnetic particles, hence all kinds of waves, including "visible light" are present of the Electromagnetic Spectrum.

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He said you can do the Quantum world problems or even the problems from the fundamentals for practice

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To calculate the limiting reactant, you would also need to know how many moles of BrF3 we have in the reactants, along with .30 moles of ClO2. This, or least the mass of BrF3, would need to be given in order to find out what the limiting reactant is. But the general rule in order to find the limitin...

AGulati_4A

After dividing each molar value by the lowest one in the group, you have to just multiply those values you get and make them hole numbers. these numbers would be the empirical subscripts for your answer

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Watch this video, it is super helpful: https://www.khanacademy.org/math/arithmetic-home/arith-review-decimals/arithmetic-significant-figures-tutorial/v/addition-and-subtraction-with-significant-figures Also, you are simply taking the number with the least amount of sig figs, as you don't want your a...

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Haley Chun 4H wrote: Avogadro's number. Sorry to be so technical, but this number would be considered Avogadro's constant as you are using (6.023 x 10^23 atoms/ mol) not just atoms).

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Formula units is the number of atoms in in a certain quantity of a compound. In this case, you would simply need to cover .750 mol into number of atoms thus multiplying it by (6.023 x 10^23 atoms/mol) -- or Avogadro's constant

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When adding or subtracting, you always take the number with the lowest # of sig figs; this is so that you are not making the answer more precise than any of its individual parts. Watch this Khan Academy video, it's so helpful: https://www.khanacademy.org/math/arithmetic-home/arith-review-decimals/ar...

AGulati_4A

This really helps! Thank you

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That genuinely sounds awesome! I have always heard several stories of how much joy people derive from medicine but to hear it from a perspective of a Bruin really makes me happy and optimistic about the future.

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