CHEMISTRY COMMUNITY

Anish Patel 4B

Do we just need to know the reactants that form the salt and see if those reactants can form strong acids/bases?

Anish Patel 4B

YEs since fluorine is the most electronegative, it has the highest electron withdrawing ability making the molecule more stable and less able to dissociate its H+ ions in water.

Anish Patel 4B

Typically bases with hydroxides are considered strong bases, the book also has exampels that could be exceptions.

Anish Patel 4B

If the compound is an anion, you would use ferrate but if it is neutral you would just write iron.

Anish Patel 4B

E/-h can be rearranged (based on the E=hv and c=lambda * v equations) to represent the left side and the coefficients of the right side of the equation. N2 is used when you are trying to determine the change in energy when an electron switches from different energy levels (n) which is when you would...

Anish Patel 4B

First part is no since the entire molecule has the same number and types of bonds/lone pairs of electrons. Second part is lewis acid since B(OH)3 gives a proton of one of its Os to H2O to form H3O+. Since B(OH)3's conjugate base is [B(OH)4]-, we know that boric acid must lose an H in a solution so i...

Anish Patel 4B

Cl- is a neutral ion and thus does not affect pH of a solution. If you are able to write the acid disassociation equation with the ion on both sides, you know that the atom is neutral.

Anish Patel 4B

Since H3PO4 is polyprotic, shouldn't it be a stronger acid than HClO4 despite Cl's electronegativity?

Anish Patel 4B

It depends what molecules the salt breaks up into, depending on what other reactants are present in the chemical equation. For example, dissolving the salt of strong base and strong acid makes a neutral solution, salt of strong base and weak acid makes a basic solution, and lastly, a salt of weak ba...

Anish Patel 4B

To calculate pH, you take the negative log of the concentration of hydronium.

Anish Patel 4B

WHat is the best way to determine if a ligand is a chelating one?

Anish Patel 4B

There are test banks, I believe there is one at the student activities center (but you have to submit a test first), that have previous tests. I know some clubs/orgs on campus have their own ones as well.

Anish Patel 4B

If there is a neutral molecule too, do you write its name before the hydrate?

Anish Patel 4B

Is that the best way to determine how many bonding areas there are for a ligand?

Anish Patel 4B

Based on what he said in class, a heme complex forms when an iron ion binds to the porphyrin ligand. When this complex binds with another protein (the example he used was histidine), they make up myoglobin (responsible for transporting O2 in muscles cells.

Anish Patel 4B

Since pi bonds represent parts of double and triple bonds (which are considered stronger than single bonds), why aren't pi bonds stronger?

Anish Patel 4B

Memorization might be needed for the charges of certain transition metals depending on the ionic compound they create with another element. For example, platinum ion has the possibility of having 2+ or 4+ charge.

Anish Patel 4B

yes, you still should figure out the dipole moments of all the atoms to determine the overall net dipole moment of the molecule

Anish Patel 4B

hydrogen bonds are the strongest

Anish Patel 4B

Yes, 2 bonding atoms and 1 lone pair is also a bent shape. Since there are two lone pairs in the first example, this molecule's atoms experience more repulsion and are pushed closer together which decreases the bond angle in comparison to a bent molecule with only one lone pair.

Anish Patel 4B

When you complete the octets of the chlorine atoms, you have 24/28 electrons filled for the molecule. Adding double or triple bonds would decrease this number of overall electrons used by taking one from each atom. The only way to fill the quota of 28 electrons is to add two lone pairs, which is pos...

Anish Patel 4B

How do you determine whether electrons are axial or equatorial?

Anish Patel 4B

You don't need to know the exact values but the general trends (F being the most) and the fact that noble gases have none.

Anish Patel 4B

Not sure if this is what you're exactly referring to but the number of lone pairs, which force bonded electron pairs closer to one another, decreases the bond angle

Anish Patel 4B

If there are more lone pairs present, the repulsion that they cause forces the bonding atoms away causing there to be a decrease in bond angle size. Lavelle said you do not need to know the exact numbers but the idea that more lone pair electrons force bonding electrons closer together, decreasing a...

Anish Patel 4B

lone pairs count towards molecular geometry not electron domain geometry. so in the case of 4 electron domains (3 bonding and one lone pair), the electron domain geometry would be tetrahedral while the molecular geometry would be trigonal pyramidal.

Anish Patel 4B

Elements that have a high need to complete their valence shell through adding electrons have higher electronegativity values (since that is its ability to attract an electron to itself). Fluorine has the highest since it needs one more electron to complete its valence shell and experiences less elec...

Anish Patel 4B

in order of strongest to weakest forces:
ion-ion, h, ion-dipole, dipole-dipole=london dispersion (depending on molecule size)

Anish Patel 4B

You want to fill the octets of outside atoms first, then try and complete the octet of the central atom. If you are missing electrons, usually a double or even triple bond will help. The central atom should usually have a complete octet though there are exceptions like Dr. Lavelle discussed in class.

Anish Patel 4B

Here is what I wrote down in my notes:
Less than 8 e-: H, B, He, Be (Aluminum and Boron only need 6 valence electrons)
More than 8 e-: P, S, Cl, Xe and below

Anish Patel 4B

APatel_4A wrote:How do we know what the central atom should be?

The central atom is usually the least electronegative one.

Anish Patel 4B

To add to this, Boron (and elements under) have higher ionization energies than Beryllium (and elements under) for a similar reason of electron shielding.

Anish Patel 4B

Molarity is equal to moles of solute per one liter of solution. So if there is a question that tells you there is a certain amount of a compound dissolved into water, you would find the molarity of that solution by using the formula (you might have to convert grams to moles or milliliters to liters)...

Anish Patel 4B

It is also important to know that the balmer series deals with visible light while lyman deals with UV.

Anish Patel 4B

Do you know if this also includes the material from the first test since it was high school stuff?

Anish Patel 4B

Lewis structures with formal charges of each atom that are closest to 0 represent the lowest energy arrangement of the atoms and electrons within a molecule. So, the lowest formal charges of a molecule are typically more representative of the true nature of that molecule.

Anish Patel 4B

Writing the electron configuration first is a good way to go because you need to determine what sublevel each atom has valence electrons in. When you form a positive ion, you take away electrons from the valence level first.

Anish Patel 4B

These are atoms that have at least one unpaired electron which can be identified by drawing their lewis structure or writing their electron configuration.

Anish Patel 4B

Electronegativity increases from left to right on a periodic table while decreasing down a group, so the order would be:
selenium, antimony, tin, indium

Anish Patel 4B

For 1E.17, it asks what type of orbital an electron will be removed from (1s, 2p, 3d, 4f, etc.) for various atoms. What are the rules for which orbitals are removed before others?

Anish Patel 4B

In class, Dr. Lavelle said to write configurations in order of increasing energy. However, in the book it gives examples/answers in a different way where the configuration is written in the order of increasing coefficients for each sublevel (Ex for bismuth: [Xe] 4f^14, 5d^10, 6s^2, 6p^3). Does the b...

Anish Patel 4B

Since we are dealing with the lyman series (uv light), n1 is equal to 1. Rearranging the rydberg equation from the book, you can plug in the known values (for speed of light, lambda/wavelength, rydberg's constant, and n1) and solve for n2 (the final energy level): v=c/lambda=r(1/(n1)^2 - 1/(n2)^2) w...

Anish Patel 4B

In the p shell, there are 3 orbitals in which electrons can exist: px, py, and pz. The subscript tells you how the orbital is oriented where px is located along the x-axis. The 2 in front says that the electron exists in the second level of the p subshell and in the first orbital.

Anish Patel 4B

Energy of one photon = hv
1. Use the equation c=lambda * v to get the frequency
2. Use the frequency to find the energy of one photon using (E=hv)
3. Then use the energy given (11 J) and divide it by the energy of one photon to determine the number of photons generated

Anish Patel 4B

Diffraction is the main one that he discussed in class. Constructive interference, where waves with same peaks interact with one another and gain amplitude, and destructive interference, where peaks interact with troughs and diminish in amplitude, both also can be used to describe diffraction patter...

Anish Patel 4B

What units does keV refer to? Since it is for energy, how would you convert this to joules or do you use these units instead for calculations?

Anish Patel 4B

The equation is: En = -hR/n^2 where n is the energy level of the electron and r is rydberg's constant (3.29*10^15 Hz) The different series (balmer,lyman, etc) are used to describe the lines of emissions of the electrons of the Hydrogen atom but we have not discussed whether they can be used for othe...

Anish Patel 4B

I know that the correct answer is D, but is it because of the way the electromagnetic radiation acts when it leads to the emission of electrons for the photoelectric effect or is there another reason that supports the idea that light has particle-like properties?

Anish Patel 4B

Yes, the electron moves from energy levels 1 to 3 as it emits the specific energy.

Anish Patel 4B

Are there any real-world/naturally occurring examples of the photoelectric effect? I don't see how this effect manifests itself besides in a laboratory setting.

Anish Patel 4B

molarity=mol/volume of solution
So, you first can calculate the molarity of the sodium carbonate solution. With this, you can use the mole to mole ratio of the various compounds in each part and the molarity equation to calculate the desired amounts needed for the volumes.

Anish Patel 4B

Units wise, lamba (wavelength) is represented by meters while nu (frequency) is represented by Hz or 1/s. When you multiply the two, you get m/s which is why the product of the two gives you the speed of light, c.

Anish Patel 4B

E=energy of photon
h=planck's constant (6.626 × 10-34 m^2*kg/s)
v=frequency in Hz

Anish Patel 4B

It is definitely a confusing question and I think it asks what is common with all the electrons found within a certain series. One thing is that they all have the same base energy level.

Anish Patel 4B

Diazepam, a drug used to treat anxiety, has the mass percentage composition 67.49% C, 4.60% H, 12.45% Cl, 9.84% N, and 5.62% O. What is the empirical formula of the compound? I was wondering how we would calculate the molar mass of diazepam to solve for its empirical formula? Is this a common compou...

Anish Patel 4B

Measuring errors in which compounds are thought to weigh less than they actually do could contribute to a greater yield than calculated. Certain chemicals also "age" with time and can produce byproducts that increase mass that may not be considered in calculations. Generally, any informati...

Anish Patel 4B

The question gives you the formula for the desired compound as M2O. This means that there are twice as many moles of oxygen as there are for M. So, we can determine the mass of O in the compound by first assuming the mass of the compound to be 100g. As a result, 100-88.8 = 11.2 grams of oxygen. We c...

Anish Patel 4B

On the reactants side, you have 4 moles of butane reacting with 26 moles of oxygen. This produces 16 moles of carbon dioxide and 20 moles of water. All compounds are gases so you have 30 total moles of gases on the left side of the equation and 36 moles of gases on the right. 36 - 30 = 6 moles of ga...

Anish Patel 4B

From my experience, common compounds (such as acids/bases, gases, and salts) and reactions (combustion) are usually easily identifiable based on their molecular formula. For example, acids/bases are aqueous in a solution with water while all reactants/products in a combustion reaction are gases. Als...

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