CHEMISTRY COMMUNITY

Shirley_Zhang 3O

Why do sodium, carbon, hydrogen, and oxygen taste so good together?
- NaCHOs

Shirley_Zhang 3O

The energy is determined by how far the neighboring atoms are spaced out, not how big the angles are.

Shirley_Zhang 3O

Exergonic refers to the negative change in Gibbs free energy, whereas exothermic refers to the negative change in enthalpy.

Shirley_Zhang 3O

I suppose when you say "it is not obvious," you mean that the elements do not have obvious partial charges that are used to classify them as nucleophile or electrophile. In this case, you would need to look at the elements' likelihood of accepting or donating electrons. If the element acce...

Shirley_Zhang 3O

Some students asked the same question couple years ago, and here is what Dr. Lavelle posted back then: "A unique rate is a rate of appearance/disappearance of any of the species in a reaction divided by its stoichiometric coefficient. A unique rate will be the same for each reactant or product....

Shirley_Zhang 3O

Cv,m stands for the molar specific heat capacity under constant volume, so you use Cv,m when volume is constant. Cv,m = 3R/2 because the object is assumed to behave IDEALLY. This does not mean that Multiplying Cv,m with "n" gives you the specific heat capacity of whatever object you are ca...

Shirley_Zhang 3O

Shirley_Zhang 3O

I am not sure if I am correct, but here is what I think. The heat capacity of the calorimeter remains unchanged regardless of the rxn that takes place inside because heat capacity measures how much heat is needed to rise the temperature of the system by 1 degree. Heat capacity is an intensive proper...

Shirley_Zhang 3O

The two factors that change entropy (the probability of a system being in a particular state) are heat and expansion. The entropy associate with heat is called THERMAL ENTROPY, which is calculated by reversible heat divided by temperature. The entropy associated with expansion is called is RESIDUAL ...

Shirley_Zhang 3O

Adiabatic means that no heat leaves or enters the system.

Shirley_Zhang 3O

There is no difference between the two formula.

Shirley_Zhang 3O

the strong acids are usually composed of hydrogen + group 1 or group 2 elements because these compound desolve easily in solvent, thus contributing a large increase to the concentration of hydronium ions. I don't think there's a way in determining the strength of an acid based simply on the chemical...

Shirley_Zhang 3O

Remember that pOH and pH are reverse of each other.
First, you calculate the "-log[conc. of hydronium]" which gives you pH
Then, from the equation "pH + pOH = 14" that we derived in class, you can plug the pH value and solve the equation.

Shirley_Zhang 3O

"K" does not mean any particular number in chemical equilibrium
"Kc" is the equilibrium concentration
"Kp" is the equilibrium pressure

Shirley_Zhang 3O

Bond order explains bond stability. It is not an indication of how many bonds a atom can form.

Shirley_Zhang 3O

Lone pair is considered as an electron density region, so it does affect the number of hybridization orbitals.
The hybridization orbitals for a central atom with three bonds and one lone pair are sp³.

Shirley_Zhang 3O

One general rule to determine the polarity of a molecule is to see whether the bonding electron pairs are scattered evenly around the central atom. If they are evenly scattered, then the molecule is nonpolar. (The idea behind this guideline is that the difference between partial charges of surround...

Shirley_Zhang 3O

After actually doing #59, and I used double bond; I think it would be better to put the extra electron on chlorine because chlorine can have expanded octet.
adding electron to oxygen would give you a final charge of -1 instead of zero

Shirley_Zhang 3O

At this point, I would refer back to the octet rule.

Shirley_Zhang 3O

I think it does have to do with the formal charges. The lewis structure for XeOF₄ has FC of zero.
One important thing to note is that having a negative partial charge is not preferable because the surrounding atoms have higher electron affinity.

Shirley_Zhang 3O

You use brackets "[ ]" for ionic bonds.
You use dashes "___" for covalent bonds.

And you use the difference in electronegativity to determine whether a molecule has ionic or covalent bonds.

Shirley_Zhang 3O

I confirmed with Dr. Lavelle that assigning coordinates ( x, y, z, etc) to orbitals is arbitrary. He will not test us on that, so we do not have to worry too much. :)

Shirley_Zhang 3O

Also, if you have part of a formula in parenthesis, such as

(NH₂) XYZ , where X, Y, and Z represent some random atoms

the 2 hydrogen atoms are attached to the nitrogen atom when drawing Lewis Structure.

Shirley_Zhang 3O

They describe the locations of electrons in a P-orbital. So instead of saying "these electron are in the front and back," we can say "their positions are on the x-axis" since they are in P-orbital, we state their location as "Px" same idea for Py and Pz Do you know how...

Shirley_Zhang 3O

What is the actual meaning of the formal charge of an atom, and how does it affect the compound? I understand that we want all the atoms to have formal charges of 0 because this indicates that it is the most "stable", but what does this really mean/refer to? You want the formal charge of ...

Shirley_Zhang 3O

Joslyn_Santana_3A wrote:Here is an example of Xe breaking the octet rule.

Yes, you are right that both the S and P orbitals are filled, but Xe also has 5d orbitals that is shown in period 6 on the periodic table, so the extra pairs of bonds occupy the d-orbitals

Shirley_Zhang 3O

We must note that before atomic number 20, there''s no d-orbitals. The general guideline is that once the d-orbitals at n-th energy level are filled, their energy levels drop below the s-orbitals of n+1st energy level; therefore d-orbitals, if exist, from n-th energy level should be written before s...

Shirley_Zhang 3O

The electrons are in the state of somewhere in between.

Shirley_Zhang 3O

Even thought both equations contain velocity, calculating Ek doesn't help you to solve for wavelength. At least with what we have learned so far, we do not know how to convert Ek to wavelength or frequency.

Shirley_Zhang 3O

They describe the locations of electrons in a P-orbital. So instead of saying "these electron are in the front and back," we can say "their positions are on the x-axis"
since they are in P-orbital, we state their location as "Px"

same idea for Py and Pz

Shirley_Zhang 3O

Based on the information given by the following website http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/wvfun.html#c2 It seems to me that: Psi itself gives you a prediction of position and time of an electron. Psi gives you the shape of an orbital Psi square represents to probability of finding a...

Shirley_Zhang 3O

Hertz = 1/second or second^-1
so if we ignore the number, the calculation would look like the following:

(meter*second^-1) / (meter) = second^1 = hertz

which corresponds to

speed of light / wavelength = frequency

Shirley_Zhang 3O

For your second question:
the elements in the s-block go from group(column) 1 to group 2
the elements in the p-block go from group 13 to 18
the elements in the d-block go from group 3-12
f-block would be the last two periods (6 and 7)

Shirley_Zhang 3O

1.14E14 = -3.29E15 [(1/n^2) - (1/4^2)]

n^2 = 1/(1.14E14/-3.29E15 + 1/16)

square root both sides and you will get an answer that is close to an integer. :)

Shirley_Zhang 3O

Given the shortcut formula: frequency = -R [(1/n*2) - (1/N*2)] in which "n" is the initial energy level, and "N" is the final energy level. you basically substitute all the values into the formula and solve for "n". if the negative signs are confusing, try to distribute...

CHEMISTRY COMMUNITY

Search found 35 matches

Re: Post All Chemistry Jokes Here

Re: Butane - Gauche formation

Re: exergonic vs exothermic

Re: Electrophile Vs. Nucleophile

Re: Unique Rate of A Reaction

Re: constant volume and pressure

Re: Post All Chemistry Jokes Here

Re: Calculating Internal Energy Change

Re: Entropy

Re: Adiabatic

Re: Q and K [ENDORSED]

Re: Strong Acid or Weak Acid

Re: pOH from pH [ENDORSED]

Re: The difference between K, Kc, and Kp

Re: Boron M.O. and Bond Order?

Re: Lone pairs [ENDORSED]

Re: Molecular Shape and Polarity

Re: HW 3.59

Re: HW 3.59

Re: Octet exceptions and double bonds

Re: When are you supposed to know?

Re: Px, Py, Pz [ENDORSED]

Re: Order or formula

Re: Px, Py, Pz [ENDORSED]

Re: Formal Charge Meaning

Re: Lewis Structures

Re: d-block electron configuraitons

Re: Electrons in Resonance [ENDORSED]

Re: Question: How should I decide if I use DeBroglie Equation or the equation for Kinetic Energy?

Re: Px, Py, Pz [ENDORSED]

Re: wavefunction, psi, and orbitals [ENDORSED]

Re: Problem 7 Quiz 1 Preparation in the Workbook [ENDORSED]

Re: orbitals

Re: Rydberg Equation Post Assessment Problem

Re: Rydberg Equation Post Assessment Problem