CHEMISTRY COMMUNITY

Savannah Torella 1L

As stated above, HBr is only the list of strong acids while HBrO is not, so HBr is automatically a stronger acid. For a reminder the list of strong acids is below.
Strong acids:
HCl
HBr
HI
H2SO4
HNO3
HClO4
HClO3

Savannah Torella 1L

I also struggled with this problem. K2SO3 would be basic since SO3^2- could accept a H+ from water, producing HSO3^- and OH-. Since OH- was produced, this whole compound is basic.

Savannah Torella 1L

Given pH and pKa, it is important to know the following with the given equation
pH>pKa, deprotonated species of A- will be more present (which means it'll be charged)
pH<pKa, protonated species of HA will be more present(which means it'll be neutral)

Savannah Torella 1L

I was also having trouble with this problem at first. Acids start with an H or end with COOH. Strong bases often start with a metal and end in OH, and weak bases often contain N. Since NaCl does not contain H+ or OH-, it would be neither an acid or a base. It's actually a salt.

Savannah Torella 1L

As stated above, an amphoteric substance contains hydrogen and a negative charge. The hydrogen allows H+ to be donated, making it a bronsted acid. The negative charge means that a H+ can be accepted, also making it a bronsted base.

Savannah Torella 1L

To find the oxidation state of the metal, which is Co, you first have the recognize the charges of the other atoms. NH3 has no charge and each Cl has a -1 charge. Since the overall charge is zero, you can use the equation (0)= (Co charge)+(0)+(-2)+(-1). This gives the metal atom a +3 charge.

Savannah Torella 1L

You first want to focus on the atoms inside the bracket. For NH3, you change ammonia to ammine and since there are 5, it is pentaammine. For Cl, you change chloride to chloro. Then you have to find the charge for Co, which can be found using the equation 0= (Co)+(0)+(-1)+(-2), giving you cobalt(III)...

Savannah Torella 1L

I was also confused with this at first. Since it was only asking for the common shapes, a seesaw would not be included. Since the seesaw has 5 e- density regions, it is not as stable as ones that have 4 or 6, making it less common.

Savannah Torella 1L

The oxidation state is the sum of all of the charges. You already know that Cl has a -1 charge, and that there are two of them. Since the overall charge is -1, you can use the equation -1=(-2)+(Cu charge) in order to find the oxidation state for the central atom. You should get +1 as your answer.

Savannah Torella 1L

As mentioned above, the coordination number is the number of donor atoms (or ligands) that are bonded to the central metal atom. Just a reminder that ligands only exists inside of the brackets. For [M(CO)3Br3], the central atom is M. Since there are 3 B and 3 CO molecules surrounding M, the coordina...

Savannah Torella 1L

Yes, lone pairs count as their own region of electron density. That is why the shape of a compound is dependent on both the number of outer atoms and the number of lone pairs.

Savannah Torella 1L

H2O has a bent shape because it has two outer atoms (the two hydrogens that it bonds to) and two lone pairs (the 2 lone pairs from oxygens).

Savannah Torella 1L

The axial atoms are in linear arrangement around the central atom, meaning they are 180 degrees. These atoms would be similar to the North and South Pole, straight up and down in 2D. The equatorial atoms are the other atoms that occupy positions located on the equator of the central atom, or the one...

Savannah Torella 1L

The shape would be tetrahedral because the carbon has four regions of electron density. These four regions are the two bonds with hydrogen and the two bonds with the neighboring carbons.

Savannah Torella 1L

As explained above, you need to find the empirical formula. You do this by converting the percents to grams then dividing each element by its molar mass to get the amount of moles of each element. You then divide by the smallest value, which gives you CH4O. You then draw the Lewis structure so that ...

Savannah Torella 1L

A Polar molecule has bonds with dipoles that don't cancel. The lone pairs come into play because they affect the shape of the molecule. In order for the dipoles to cancel, they have to be across from one another in different directions. The shape determines whether or not the dipoles are directly ac...

Savannah Torella 1L

The negative poles of a molecule are located towards the more electronegative atom in the compound. Also, the larger the electronegativity difference is between two atoms, the larger the vector is towards the negative pole.

Savannah Torella 1L

The seesaw shape contains 90 and 120 degree angles. The lone pair interacts with two bonds at 90 degrees. The other bonds on the equatorial plane are 120 degrees.

Savannah Torella 1L

H2O is bent because it contains 2 outer atoms and 2 lone pairs. The lone pairs come from oxygen, since there are only 2 single bonds present with the hydrogens.

Savannah Torella 1L

When looking at atomic orbital models, a sigma bond is present when the ends of the orbitals interact with each other. A pi bond is present when the orbitals overlap side to side, crossing paths twice instead of once. When looking at Lewis structures and VSEPR models, a sigma bond is present when th...

Savannah Torella 1L

There are two ways to distinguish why the double bond is needed. You can either look at the charge of the compound or the number of valence electrons that As require. Oxygen has a -1 charge when it has a single bond, since it is surrounded by 7 electrons when it only needs 6 valence electrons. This ...

Savannah Torella 1L

Molecules that are highly electronegative are N,O, and F, which means these are the atoms that can form hydrogen bonds. Carbon couldn't form a hydrogen bond because it's electronegativity is too close to hydrogen's.

Savannah Torella 1L

Can someone explain what the interaction potential energy equation would be used for and what this equation is composed of?

Savannah Torella 1L

The nitrate ion has a +1 charge because on the periodic table, you can see that nitrogen has 5 valence electrons. However in nitrate, nitrogen is only connected the 4 electrons, sharing two from a double bond with oxygen and sharing two from 2 single bonds with O. Since the nitrogen atom is missing ...

Savannah Torella 1L

We do not need to know how to calculate for bond lengths. In lectures, Dr. Lavelle told us that the values given to us were ones that he looked up, meaning that we wouldn't be expected to find them ourselves. All you need to know is that the bonds from longest to shortest are single, double, triple ...

Savannah Torella 1L

The atomic radius is the distance between the nucleus and the element's normal valence electrons, while the ionic radius is the distance between the nucleus and the outermost valence electron of the ion. The ionic radius of a positive ion is smaller than the atomic radius of the element, while the i...

Savannah Torella 1L

In Lavelle's lecture, he mentioned that electrons involved in resonance structures are delocalized. I was just wondering what delocalized meant for an electron.

Savannah Torella 1L

When drawing a Lewis dot structure for an element, does it matter which order you place the dots in? I thought I remembered there being a specific order in high school, but it doesn't seem to be mentioned now.

Savannah Torella 1L

In simple terms, resonance is when a Lewis structure can show more than just simple bonds, ie double or triple bonds, and that these bonds can be placed anywhere on the structure and still make the structure true. For example, for NO3- a double bond can be placed between any N and O, as long as one ...

Savannah Torella 1L

Double bonds are shorter than single bonds because they contain more electrons. When an anion contains a large amount of electrons, that means that it can be more easily pulled into a cation. When the two are easily pulled into each other, that results in a shorter bond length.

Savannah Torella 1L

As mentioned above, H, He, Li, and Be are exceptions to the octet rule because they only consist of the s-orbital. Since H and He only contain the 1s orbital, and Li and Be only contain the 1s and 2s orbitals, none of these elements can hold 8 valence electrons. Without containing the p orbitals, th...

Savannah Torella 1L

As, fellow students above have mentioned, cations are always smaller than their parent atom, and anions are always larger than their parent atom. That means for any element given, the radius size from largest to smallest would be Cs-,Cs,Cs+.

Savannah Torella 1L

I was having trouble figuring out how many electrons could have the set of quantum numbers n=5, l=2. I eventually discovered the answer was 10 but I was wondering if somebody could explain why that is.

Savannah Torella 1L

I was just wondering if anyone had an example of a word problem where the Schrodinger equation would be used. I'm having trouble understanding its application to current questions we have been approaching.

Savannah Torella 1L

What are all the units that should be used when a value is being calculated with the DeBrogile equation? I kept mixing my units up during Sapling problems.

Savannah Torella 1L

When do you want to use the Avogadro constant? How are you able to tell when it is needed?

Savannah Torella 1L

Yes, 2.5 micrometers should be used as the wavelength. Just make sure you convert micrometers into meters first!

Savannah Torella 1L

Wavelength is usually measured in meters, while frequency is usually measured in Hz or s^-1. However, I have seen nm used a lot on Sapling problems, so I think it would be beneficial to know how to convert between the two. Nanometer is 10^-9, so to go from nanometer to meter you would move 9 spaces ...

Savannah Torella 1L

How do you know when you are finding the normal energy versus the threshold energy? I am still a little confused by that.

Savannah Torella 1L

When using the equation E= hc/ wavelength, is c always going to be the speed of light constant? Are there any instances were c is a different variable?

Savannah Torella 1L

Although both of these equations involve the variable v, the v stands for different things in each each. In De Broglie's Equation, the v stands for speed/ velocity. In c= wavelength(v), v stands for frequency. This means that if the problem involves speed, you use De Broglie, and if the problem invo...

Savannah Torella 1L

Could someone explain the way to use this acronym? How many times you move the decimal places moving up or down, I am a little rusty on it. In addition, what is the "middle" starting point? When using the acronym "King Henry Died By Drinking Chocolate Milk," the starting point i...

Savannah Torella 1L

If you are talking about the model that was given during the presentation, which I'm pretty sure you are, it's because this graph is based off each specific energy level. Under the Lyman series, it is showing that the electron can jump between levels ranging between the first energy level and the si...

Savannah Torella 1L

I would definitely be interested! My email is storella@ucla.edu if you ever need to contact me about studying.

Savannah Torella 1L

When it comes to electron configuration, you want to write the orbitals in the order that they were fully filled. In the context of your question, 3d would be written before the 4s since the 3d orbital is filled up first between the two.

Savannah Torella 1L

I think a few people have answered this, but protons and neutrons have similar masses. This is why the atomic mass is determined by the amount of both protons and neutrons.However, electrons are drastically smaller in comparison to protons and neutrons. They are so small that their weight is not inc...

Savannah Torella 1L

I know that this picture can look very overwhelming at first, but don't be discouraged. When using the picture, you do not need to pay attention to the different kinds of bonds formed. Whether it is a single bond or a double bond, it does not effect the molecular formula or mass. All you need to do ...

Savannah Torella 1L

Usually while calculating, I use all of the decimals given on the periodic table. I don't know how different it is for every table, but mine has three number after the decimal point. I use all of those decimal until the very end. I then round my answer by the same amount of decimal places given to o...

Savannah Torella 1L

I think you may have calculated the molar mass of CuNO3 incorrectly. Using the periodic table, 63.546+14.007+(3*15.999)= 125.55gmol^-1. Hope that helps!

Savannah Torella 1L

From my past learnings, this is indeed the case. When there is a combustion, that means that oxygen and heat is involved. With hydrocarbon compounds, H2O and CO2 are produced. So I think it's safe to say that + O2 -> H2O + CO2 is always used for combustion reactions. Although, I think there are occa...

Savannah Torella 1L

For number 7, you are trying to find the mass/moles of the solute(n), and you are given the mass percentage of CaCl2. With the mass percentage, you can divide that number by 100 to get the molarity of CaCl2. After finding the volume of the solution (using the periodic table), you can plug M and v in...

Savannah Torella 1L

This is very helpful thank you for your perspective! I am one who always keep my notes but never end up using them, so it is encouraging to know that these notes helped you with future classes.

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