CHEMISTRY COMMUNITY

Mallika Chimpiri 3K

This is because Guanine has Nitrogens with lone pairs that bond with the Cl atoms in cisplatin.

Mallika Chimpiri 3K

NH3 is amphiprotic, meaning it can act as a base or an acid, so you have to look at the reaction!

Mallika Chimpiri 3K

We learn to calculate this in 14B!

Mallika Chimpiri 3K

You should specify 2sp2 only if the orbital is asked!

Mallika Chimpiri 3K

No, ate is only added to an anion!

Mallika Chimpiri 3K

Are there any acids that we should memorize and be able to name if used in a question?

Mallika Chimpiri 3K

Do we have to memorize the common ligands chart in section 9C.1 of the textbook?

Mallika Chimpiri 3K

I would definitely take advantage of the review material and session provided by the Undergraduate and Teaching assistants!

Mallika Chimpiri 3K

This is because depending on the molecule, conjugates of it may affect the concentration of hydroxide and hydronium ions, which affects the pH.

Mallika Chimpiri 3K

Yes it does work, you just have to account for lone pairs when determining hybridization.

Mallika Chimpiri 3K

The greater the molar mass, the higher the boiling point.

Mallika Chimpiri 3K

Electronegativity and atomic size have opposite trends.

Mallika Chimpiri 3K

Si2F2 has stronger intermolecular forces because it is more polar. SiF4 is non polar.

Mallika Chimpiri 3K

It would be square planar.

Mallika Chimpiri 3K

No, resonance just refers to variations in writing the structures.

Mallika Chimpiri 3K

A single bond has a sigma bond, a double bond has one sigma bond and one pi bond, a triple bond has one sigma bond and two pi bonds.

Mallika Chimpiri 3K

Yes, it should be less than 90 and 120.

Mallika Chimpiri 3K

is hybridization and sigma/pi bonds going to be on test 2?

Mallika Chimpiri 3K

Ziyan Wang 3J wrote:In order to fulfill octet rule, there must be two lone pairs of electron around O (since bonding pairs only account for four electrons), thus O have 4 electron domains and its bonding angle is 109.5 (similar to tetrahedral).

that makes sense, thank u!

Mallika Chimpiri 3K

Does anyone know what the format of Test 2 will be?

Mallika Chimpiri 3K

Yes they are considered regions of electron density

Mallika Chimpiri 3K

This is because although IF4- has 6 areas of electron density, you only look at bonded electrons when determining molecular shape. It has 4 bonds with 2 lone pairs, which gives it an octahedral electron arrangement but a square planar molecular geometry.

Mallika Chimpiri 3K

To find the hybridization, count up how many bonds and lone pairs the atom has. If it is 3, then the hybridization would be sp². If it is 4, then the hybridization would be sp³, and so on. For BeCl2, Be is the central atom and has 2 bonds and no lone pairs, so its hybridization would be sp.

Mallika Chimpiri 3K

For homework problem 2.63, why is the bond angle for arc b 109.5 degrees?

Mallika Chimpiri 3K

Can someone explain how to determine if a molecule is polar or non polar by looking at its molecular geometry/shape?

Mallika Chimpiri 3K

What are all the topics included on Exam 2?

Mallika Chimpiri 3K

Does anyone know which week Test 2 will be?

Mallika Chimpiri 3K

In the first equation, B is counted as a bond, while in the second equations B is counted as each shared electron. That's why when counted as singular electrons, it has to be divided by 2 to account for the bonds.

Mallika Chimpiri 3K

To determine magnetic quantum number (ml), you must look at the angular momentum number (l). ml can be any value from -l to +l. For example, if l=2, then ml=-2, -1, 0, 1, 2. If l=0, then ml has one possible value, = 0.

Mallika Chimpiri 3K

Can anyone explain the periodic trend for polarizability and the trend for polarizing power?

Mallika Chimpiri 3K

Can anyone explain the periodic trend for polarizability and the trend for polarizing power?

Mallika Chimpiri 3K

How exactly does a dipole moment occur? and how is it induced?

Mallika Chimpiri 3K

Can someone explain what effective nuclear charge means?

Mallika Chimpiri 3K

1 cycle/second!

Mallika Chimpiri 3K

Does anyone know when/where the step up sessions are for this Monday and Tuesday?

Mallika Chimpiri 3K

Yes! We have one more test and then our final.

Mallika Chimpiri 3K

The octet rule basically means an atom must have 8 electrons in their valence shells and will bond in arrangements that allow for that. But there can be exceptions to the octet rule, such as CH3 and BF3 where the atom in the center doesn't have a full valence shell.

Mallika Chimpiri 3K

You can figure out if resonance occurs when you draw out the Lewis structure. For example for a nitrate ion (NO3-), an NO double bond is required for all 4 atoms to have an octet. Because there are 3 oxygen atoms, the double bond can be drawn on any one of them, resulting in 3 possible structures.

Mallika Chimpiri 3K

I know it's still weeks away but I was wondering, does anyone know about the format of the midterm? Is it comparable to Test 1 but just longer in length? What types of questions will be on it and which units does it cover? Where is the midterm located? Will that be announced closer to the midterm d...

Mallika Chimpiri 3K

Does anyone know what all the topics for the Midterm include?

Mallika Chimpiri 3K

Aside from the textbook problems and online video modules, I would recommend doing to the Step-Up sessions and the upcoming midterm review sessions if you feel that you study well with others around; it would be a good way to clarify and reinforce concepts.

Mallika Chimpiri 3K

Test 2 is during week 8 on whichever day you have discussion! As for studying, I think the best is way to go over what the syllabus states in the textbook but go through the video modules and notes from lectures to reinforce all the material.

Mallika Chimpiri 3K

What value is recommended we use for the c constant during calculations? 2.998e8 or 3.00e8?

Mallika Chimpiri 3K

I cycle per second

Mallika Chimpiri 3K

I MHz is equivalent to 10^6 Hz, so using that conversion you should be able to go from MHz to Hz and vice versa.

Mallika Chimpiri 3K

Parallel electrons have the same spin state, meaning they both go up or both go down. Paired electrons, on the other hand, have opposite spin states, meaning one goes up and one goes down.

Mallika Chimpiri 3K

A negative charge on an ion indicates that it gained electrons, while a positive charge indicates that the ion lost electrons.

Mallika Chimpiri 3K

The N value signifies the energy level of an electron, and is called the Principle Quantum Number. The n value increase basically when an electron is excited and increases in energy level.The n value decreases when an electron emits energy and decreases in energy level.

Mallika Chimpiri 3K

If the problem requires many calculations and steps, I would end each step with more significant figures than necessary just to avoid any error. At the very end, round your final answer to how many ever significant figures are necessary. I think this is crucial because even rounding slightly up or d...

Mallika Chimpiri 3K

I don't apply sig figs in between steps or calculations just to avoid error that could come from rounding prematurely.

Mallika Chimpiri 3K

If that is the case, I would use decimal places to figure out rounding. Or, if you need to use the periodic table, use the sig figs of the molar masses to figure out the final sig fig value.

Mallika Chimpiri 3K

The conversion for Angstroms is 1 A = 10^-10 meters. Using this base conversion, you can convert to whatever desired unit.

Mallika Chimpiri 3K

For me, reading the textbook definitely helps clarify the concepts that Professor Lavelle goes over in class. The practice problems are also great review and pretty much solidify the material.

Mallika Chimpiri 3K

I believe Test 1 covers the Review of Chemical & Physical Principles. So that would be all the Fundamentals sections in the textbook.

Mallika Chimpiri 3K

You won't have to memorize the molar masses from the periodic table but if the molar mass of a compound or element isn't given in the problem, you should be able to use the periodic table in order to calculate its molar mass. Usually, the molar mass is given and calculated with 4 significant figures.

Mallika Chimpiri 3K

I would multiply to find another ratio if the decimal is more than .2 away from a whole number. So if I you had 1.1, I would just round down to 1.

Mallika Chimpiri 3K

" The molar mass of the metal hydroxide M(OH)2 is 74.10 g*mol^-1. What is the molar mass of the chloride of this metal? "
How would you go about this problem?

Mallika Chimpiri 3K

Yes, the c is a constant and will always equal 3.00 X 10^8. The frequency and wavelength vary inversely so their product will always equal the constant c.

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