CHEMISTRY COMMUNITY

ElizabethP1L

Are we expected to know the pH of different solutions like tomato juice/lemon juice?

ElizabethP1L

what makes acids strong?

ElizabethP1L

It's advised that you avoid rounding/sig figs as you work out the problem. You should use them at the very end.

ElizabethP1L

The coordination number refers to the number bonds around the central metal atom.

ElizabethP1L

Hi everyone! Did Dr. Lavelle say that we would need to know how to name coordination compounds, such as in 17.29? I thought I heard no, but I'm asking just to clarify. Thanks!

ElizabethP1L

Hi! I'm not sure where you got the 95 degrees from because I don't see that in the solutions manual. However, I can tell you that it will definitely be sightly less than 120 degrees because of the lone pair. Tin (Sn) has four valence electrons . Two of them form bonds with the 2 Cl atoms to complete...

ElizabethP1L

Hi! There are not five regions of electron density. The way the Lewis structure looks like is a double bond between 2 carbon atoms and two H atoms attached to each carbon. Since there are two central atoms here, we count the regions of electron density separately. You'll notice that around a single ...

ElizabethP1L

Hi everyone! I noticed some discrepancies on how we write the hybrid orbital for each molecule. I know that if there are five regions of electron density, for example, we use dsp3 for our hybrid orbitals (from the notes). However, my TA and the solutions manual both use sp3d instead. Are both accept...

ElizabethP1L

Hi everyone! I understand what defines an acid/base as Lewis or Bronsted. However, does this mean a Lewis base is always a Bronsted base and vice versa? Or can a base strictly be only Bronsted or Lewis? Similarly, is a Bronsted acid always a Lewis acid?

ElizabethP1L

Hey everyone! I am confused on the meaning of distorted as used in this sentence in the notes:

"Highly distorted electrons are described as being highly polarizable."

Thanks in advance! :)

ElizabethP1L

I think we can just follow the general trends for that (increasing as we go to the right of the periodic table, decreasing as we go down). If values are given, remember that an electronegativity difference greater than 2 indicates an ionic bond and one less than 1.5 shows a covalent bond.

ElizabethP1L

You were supposed to look at the double bond in relation to the entire molecule. Since SO3 consists of only double bonds it will be stronger than SO4-2 with also has single bonds that are weaker. Hope this helped! :)

ElizabethP1L

Hi everyone! I was just wondering what the main difference is between London forces and dipole-dipole. I thought they were essentially the same thing...Thanks in advance! :)

ElizabethP1L

Fluorine cannot form a double bond since it only needs one more electron to fulfill it's octet and it's unable to form expanded octets. Therefore, you would expect 3 single bonds and a lone pair on P. For VSEPR, it would not affect the general shape of the atom but angles would differ because lone p...

ElizabethP1L

Radicals are generally unstable and don't really occur in nature.

ElizabethP1L

Why is it that atoms in 3p shell and below may form expanded octets? Is it because of their access to the d-orbital?

ElizabethP1L

More ionic character means that there is a greater difference in electronegativity between the 2 atoms allowing one to strip the other of an electron making it ionic. Typically, these atoms are farther away from each other on the periodic table than atoms of covalent character that would have simila...

ElizabethP1L

Hi, everyone! I understand how to get the Lewis structure for ClNO2. Was I don't understand is why the solution manual only shows two resonance structures of it. One consists of the double bond of O to the left of N and the other shows the double bond of O above N. Why is there not a third resonance...

ElizabethP1L

If you break up the individual molecules, you'll be able to recognize if it's ionic. In the case of ammonium chloride, NH4 has a positive charge (NH4+) while chlorine has a negative charge (Cl-). These opposite charges indicate that it's an ionic compound. Hope this helped!

ElizabethP1L

I understand the formal charge would be zero. However, why don't we label it as such? When other atoms in the Lewis structure have a formal charge of zero we indicate it. Would it be wrong to include it?

ElizabethP1L

Hey, everyone! Is there a reason why the formal charge for Hydrogen is never calculated? I've noticed the solutions manual never mentions a formal charge for H. Thanks in advance!

ElizabethP1L

So, in other words, CO is an example of a coordinate covalent bond?

ElizabethP1L

Hey, everyone! I thought the definition of a coordinate covalent bond wasn't that clear from the notes, so I looked it up on Google. It says that a coordinate covalent bond is when both electrons in a bond come from the same atom. I just wanted to confirm that this is the correct definition. Thanks ...

ElizabethP1L

My TA says that when there are multiple carbons we should try to line them up horizontally and bond them. Then, try to fit in all the other components and complete their octets around the molecule. You should worry about hydrogen last since they are the easiest to accommodate since they only need on...

ElizabethP1L

Resonance structures help us to determine which form of the molecule is most stable (and therefore what would most likely be found in nature). Additionally, it shows us that molecules have different ways of distributing their electrons and bonds (they are not static the way a single Lewis structure ...

ElizabethP1L

Hey, everyone! I'm just a bit confused on the Lewis structure for carbon monoxide with consists for a triple bond with oxygen and two lone pairs (one pair on C and the other on O). For reference, see part C of HW problem 3.49. How can carbon even form a triple bond and have a lone pair left over if ...

ElizabethP1L

When do we place brackets around ions? I believe that's when you draw a Lewis structure for a charged molecule with covalent bonds like NH4+. In this case, nitrogen would have 4 valence electrons like carbon instead of the expected 5. To account for this lost electron you can put brackets around th...

ElizabethP1L

Should all resonance structures have the same formal charge?

ElizabethP1L

Will we have to use significant figures for this test just like midterm?

ElizabethP1L

A monatomic ion refers to an ion composed of a single atom like H. The charge on this monatomic ion would be +1. The opposite of a monatomic ion would be a polyatomic ion like NH4+ or PO4-3. Hope this helped! :)

ElizabethP1L

Hi! That's a very broad question! From drawing them out for homework and in class, I've noticed oxygen tends to form double bond since it has 6 valence electrons and needs two more. I don't think there's any way to know for sure. I would just try different combinations to fill each atom's octet and ...

ElizabethP1L

Hey, everyone! So I know elements from 3p and below on the periodic table are able to form an expanded octet (that is, they can have more than 8 overall electrons). However, do they ALWAYS form expanded octets (e.g. will Cl aways have more than 8 electrons in a Lewis structure)? Thanks in advance :)

ElizabethP1L

Hey, everyone! I'm not really sure how to do the following problem. I keep getting he wrong answer regardless of how many times I attempt to calculate it: The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen ra...

ElizabethP1L

Andre-1H wrote:So, even though we are not responsible for the elements that occupy these orbitals, could we then apply this to the next row and say that 4d is lower in energy than 5s? Or would that be the only exception for this line of thinking?

Yes, that's right.

ElizabethP1L

I know that the 4s orbital is actually higher than the 3d orbital and the exceptions in electron configurations that follow this rule. However, why is it that the 4s orbital is higher in energy? It's something I have just memorized, but I'd like to know the reason why. Thanks in advance! :)

ElizabethP1L

Are we expected to know significant figures for the midterm exam? Thanks in advance! :)

ElizabethP1L

What kind of light is used in the Balmer series?

ElizabethP1L

Wat kind of light is used in the Lyman series?

ElizabethP1L

Just divide the number you found that's emitted in two seconds by Avogadro's number (6.02*10^23) since there are that many atoms in just a single mole. Hope this helped! :)

ElizabethP1L

I think Dr. Lavelle is very thorough when it comes to explaining things, so maybe just use the textbook to brush up on something or for diagrams/visuals. Sometimes the practice problems throughout the chapter are good for solving the math in the exercises. Hope this helped! :)

ElizabethP1L

What kind of fish is made up of two sodium atoms?

Answer: 2 NA

ElizabethP1L

Does anyone know if we will be provided the wavelengths of the electromagnetic spectrum ?

ElizabethP1L

Hey, everyone! As I was studying the photoelectric effect I was a bit confused on something. Can anyone explain the difference between a photon and a particle if there is one? Thanks in advance!

ElizabethP1L

Don't know of many myself :( But, remember, you aren't expected to know the equations! They will be provided to you on any exam, according to Dr. Lavelle! Hope this helped! :)

ElizabethP1L

The equation most frequently used with it is the product of frequency and wavelength equaling the speed of light (3*10^8). Wavelength and frequency have an inverse relationship meaning that an increase in wavelength leads to a decrease in frequency and an increase in frequency leads to a decrease in...

ElizabethP1L

L is definitely more preferred. all the solutions in the solutions manual convert from mL to L unless the problem states that the answer should be in mL.

ElizabethP1L

The empirical formula just gives us the relative number of atoms not the actual number. Therefore, usually the empirical formula will be much smaller than the molecular formula. If you notice however, multiplying each element of the empirical formula by the same number results in the molecular formu...

ElizabethP1L

No, Dr.Lavelle said we would be provided with all constants and any outside information, including a periodic table. Hope this helped :)

ElizabethP1L

Avogadro's number is always 6.022*10^23. We mostly use it in stoichiometry. The most common uses for it is converting from moles to atoms. To do this, simply multiply the molar mass by Avogadro's number! To go from atoms to moles, divide the number of atoms you have by Avogadro's number. Hope this h...

ElizabethP1L

Well, in general, it's important to remember the basic rules and start balancing the least abundant element in a chemical equation to avoid this problem. If you still encounter it, however, you should just use a fraction to balance it temporarily. For example, let's say you need 19 Fe, but that mean...

ElizabethP1L

Hey, everyone! I had a conceptual question about the problem below: 19. During a summer camping weekend 4 moles of butane (C4H10) gas were used for cooking. Chose the right balanced equation for the combustion of 4 moles of butane gas. What is the net number of moles of gas produced? A. 4C4H10(g) + ...

ElizabethP1L

That's a very broad question! Avogadro's number is popularly used in mole conversions and stoichiometry. Typically if we want to know the number of atoms or molecules in a mole, we multiply the molar mass by Avogadro's number. To convert from atoms to moles, we must divide the atom amount by Avogadr...

ElizabethP1L

Atomic mass is simply the mass of a single atom of an element (like an atom of Na). This can be found under the element symbol on a periodic table. In this case the atomic mass is 11. The atomic mass is composed of the mass of protons and neutrons. The molar mass refers to mass of ions, atoms, or mo...

ElizabethP1L

Hey, everyone! I just had a general question about HW G.25. I understand the math behind it. However, the question asks if a very dilute solution of a substance X (presumably the solute) can still have an effect. I immediately thought yes because Dr. Lavelle mentioned that changing the volume of a s...

ElizabethP1L

Hi, Noah! I actually don't know much about the Hill System, unfortunately. In my own case, I intuitively knew the H4 would follow the Si. However, usually when the H comes first, it usually means its an acid: H2CO3 (carbonic acid) HNO3 (nitric acid) HClO4 (perchloric acid) etc.... Therefore, if it w...

ElizabethP1L

The first step is to determine the number of MOLES of each element to find the molar ratio, which will help us derive the empirical formula. The molecular formula can then be found using this formula. Since the problem did NOT specify how many grams of each atom we have, we can go ahead and assume t...

ElizabethP1L

Ideally, the problem will give you the states already. However, you don't NEED them to balance the equation. Take a look at HW problem H.1 under fundamentals for example! What's important in balancing chemical equations is the conservation of mass. As long as the same number of moles of H are presen...

ElizabethP1L

That doesn't make a big difference. Since these calculations are not being used for lab procedures, it is not important to be 100% precise. When you find the empirical formula, you round ratios as well. For example 5.12 moles of C can just be denoted 5 C in the empirical formula. Therefore, it is ok...

ElizabethP1L

Molar Mass is expressed as a capital letter M and should not be confused with molarity. Dr. Lavelle underlines the M for molarity to distinguish the two. The units for molar mass are g/mol. Hope this helped! :)

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