CHEMISTRY COMMUNITY

Yazmin Bocanegra 3L

How can you tell the difference between Lewis acids/bases and Bronsted acids/bases?

Yazmin Bocanegra 3L

What exactly is a ligand? I still don't completely understand what it is and how much of ligands we need to know for the final?

Yazmin Bocanegra 3L

VSEPR is used to determine the shape and once you have the shape, you can determine the polarity from there!

Yazmin Bocanegra 3L

6D.11. Decide whether an aqueous solution of each of the following salts has a pH equal to, greater than, or less than 7. If pH > 7 or pH < 7, write a chemical equation to justify your answer. a) NH4Br b) Na2CO3 c) KF d) KBr e) AlCl3 f) Cu(NO3)2 I need help understanding how to determine if the pH i...

Yazmin Bocanegra 3L

6C.17. Which is the stronger base, the hypobromite ion (BrO-), or morphine (C17H19O3N)? Justify your answer.

Please help, and thank you!!

Yazmin Bocanegra 3L

I think going over the learning outcomes/outlines on the class website, and checking off all of the bullet points on those sheets once you understand them will also be helpful since those are the main points for each topic we learned this quarter. Good luck and hope this helps!!

Yazmin Bocanegra 3L

Does the "s" always come before the "p" when writing the hybridization? Does it matter? Thank you!

Yazmin Bocanegra 3L

Do non-polar molecules have to be symmetrical? Or can molecules be non-polar as long as the forces all around cancel out?

Yazmin Bocanegra 3L

Are hydrogen bond sites defined by how many hydrogen atoms there are branched off of the molecule? Or are there specific properties/conditions that a branched off hydrogen atom must follow to be considered a hydrogen bonding site?

Yazmin Bocanegra 3L

Is the final exam going to be everything from throughout the quarter, or is it going to be everything from the midterm and beyond?

Yazmin Bocanegra 3L

Whenever there's only one X or one E, do we have to write a subscript of "1," or do we just write "X" and "E?" I have both in my notes and want to make sure I do whatever is preferred. Thank you!

Yazmin Bocanegra 3L

Baoying Li 4H wrote:First, draw the Lewis structure. Observe the bond between atoms.
Use these rules can help you find Sigma bonds and Pi bonds:
Single bond-one sigma bond
Double bond-one sigma bond and one pi bond
Triple bond-one sigma bond and two pi bonds

Thank you so much! Super helpful!

Yazmin Bocanegra 3L

2F.3. How many sigma-bonds and how many pi-bonds are there in
a) H2S ?
b) SO2 ?

How do you find how many sigma and pi bonds there are in a molecule?

Please help and thank you!

Yazmin Bocanegra 3L

How do you determine when to use the formal charge formula to draw your structures? And does the one with the most negative formal charge go on the left or right?

Yazmin Bocanegra 3L

How do you find sigma and pi bonds?

Yazmin Bocanegra 3L

2F.5. State the hybridization of the atom in boldface red type in each of the following molecules and ions:
a) BeCl2
b) BH3
c) BH4-
d) SiF4

How do you find the hybridization? Thank you!

Yazmin Bocanegra 3L

When drawing molecular structures, how can you tell when to draw a line (covalent bond), a shaded triangle, and dashes?

Yazmin Bocanegra 3L

Does the electronegativity increase/decrease across a group or period? And why?

Yazmin Bocanegra 3L

How can you tell which way to write a Lewis structure is the most balanced? For example, some are written with the atoms bonded vertically to the central atom, while others are written with the atoms bonded horizontally to the central atom.

Yazmin Bocanegra 3L

2A.3. Give the ground-state electron configuration expected fo reach of the following ions:
a) S^2-
b) As^3+
d) Ge^2+

Why is the answer for a) listed as just [Ar]?

Please help! Thank you!

Yazmin Bocanegra 3L

Some sections of my notes say "ground-state" electron configurations while other sections of my notes just say "electron configurations." Is there a difference between the two?

Yazmin Bocanegra 3L

How do you derive the De Broglie equation and when do you use it?

Yazmin Bocanegra 3L

When talking about light, are velocity and frequency the same thing?

Yazmin Bocanegra 3L

When using the equation, c = lambda x v, c equals the speed of light. Is the standard unit for "c" nanometers or meters?

Yazmin Bocanegra 3L

What do the "h" and "v" stand for in Einstein's equation, E=hv?

Yazmin Bocanegra 3L

How do you find molarity? Trying to review for the midterm and I can't seem to grasp it. Thank you for any help you can give me!

Yazmin Bocanegra 3L

First, you will have to write out the electron configurations for each of the elements in the question, then remove electrons from the highest energy orbital/outermost layer. For example, you will see that Zn has the highest energy orbital 4s^2, which is the outermost layer. You would remove electro...

Yazmin Bocanegra 3L

My notes have Angstrom measurements on them where I drew Lewis structures/covalent bonds. How do you calculate these, and are they important to know for this class?

Yazmin Bocanegra 3L

Are ionization energy and threshold energy the same thing?

Yazmin Bocanegra 3L

What is the definition of threshold energy and how do we find it?

Yazmin Bocanegra 3L

Does electronegativity increase or decrease as you move down on the periodic table? How about move across from left to right?

Yazmin Bocanegra 3L

What is the difference between a Lewis structure and a resonance structure? And how can you identify them?

Yazmin Bocanegra 3L

What is an expanded valence shell, and how do you identify one?

Yazmin Bocanegra 3L

If the problem does not state a positively or negatively charged element/ion, there is no need to subtract or add electrons (due to the -1/ +1 rule for cations and anions) when drawing the Lewis structure, right?

Yazmin Bocanegra 3L

What do the brackets mean in chemistry?
For example, [Ar], [Ne], [He], etc.

Yazmin Bocanegra 3L

How do you calculate the number of valence electrons just from the problem giving you the name of the element?

Yazmin Bocanegra 3L

1E.7. Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given.

The correct answer is D. but I don't understand why. Can someone please help? Thank you!

Yazmin Bocanegra 3L

1B.3. From the following list of observations, select the one that best supports the idea that electromagnetic radiation has the properties of particles. Explain your reasoning. a) black-body radiation b) electron diffraction c) atomic spectra d) the photoelectric effect The photoelectric effect is ...

Yazmin Bocanegra 3L

What's the easiest way to convert from nanometers to picometers, etc? My skills are a little rusty.

Yazmin Bocanegra 3L

Since "Hz" is for frequency and "m/s" is for speed, is there a label/unit for wavelength?

Yazmin Bocanegra 3L

1A.7. a) The frequency of violet light is 7.1 x 10^14 Hz. What is the wavelength (in nanometers) of violet light? b) When an electron beam strikes a block of copper, x-rays with a frequency of 2.0 x 10^18 Hz are emitted. What is the wavelength (in picometers) of these x-rays? I need help with this p...

Yazmin Bocanegra 3L

Accuracy is how close you are to the true value, while precision is how consistent your results are in relation to each other. For example, you can keep getting similar results that are all far off from the true value (this is good precision with poor accuracy). Hope this helps!

Yazmin Bocanegra 3L

What is a limiting reactant and how do you find/calculate it?

Yazmin Bocanegra 3L

How many significant figures should we calculate with / round to on tests?

Yazmin Bocanegra 3L

E27.
a) Calculate the mass, in grams, of one water molecule.
b) Determine the number of H2O molecules in 1.00 kg of water.

I need help with this problem. Please and thank you!!

Yazmin Bocanegra 3L

What does Avogadro's constant mean/measure? When do we need to use it?

Yazmin Bocanegra 3L

Will we need to have the molar masses of different elements memorized for the tests? If so, how many significant figures should we have down? If not, how do you calculate the molar masses?

Yazmin Bocanegra 3L

My understanding is that we will be provided formulas and maybe info/tips on what units the answers need to be written with and what format the answer needs to be in. Hope this helps!

Yazmin Bocanegra 3L

In this number, there is a trailing zero. Trailing zeros are only significant if they are part of the measurement. In scientific notation, this number would be written as 8.34 x 10^3 so the trailing zero is not significant since it is not part of the measurement. Therefore, there are only 3 signific...

Yazmin Bocanegra 3L

The best advice I can give is to take the topics that will be covered on the test, go to the syllabus and find the topics, and go through the homework problems listed on there for each topic. I also suggest going through the outlines of the learning outcomes (scroll down on the class website) for th...

Yazmin Bocanegra 3L

Why do my notes have "reactant" and "reagent?" Is there a difference between the two?

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