CHEMISTRY COMMUNITY

Jada Larson 1F

K_a is the ratio of the forward reaction to the backward reaction. It is important because for weak acids, compounds only partially dissociate into H+ ions, and there is a reverse reaction with the equilibrium constant, k.

HA <--> H⁺ + A^-

k_a = [H⁺][A^-]/[HA]

Jada Larson 1F

Why is CH3COOH a stronger acid than CH3OH? CH 3 COOH is a stronger acid because when it donates a proton, the resulting compound it forms is more stable due to delocalization of electrons. This is evident when you draw the Lewis structure, as the resulting compound has resonance. When the proton in...

Jada Larson 1F

For example, H₃PO₄ is polyprotic because it has more than one proton to donate.

H₃PO₄ --> H₂PO₄^- --> HPO₄^2- --> PO₄^3-.

Jada Larson 1F

The coordination number is the number of bonds the central metal atom is bonded to. Knowing the coordination number can help determine the name of the coordination complex. Example: vitamin b12.jpg The coordination number of the Cobalt in this Vitamin B12 is 6, and its expected geometry is an octahe...

Jada Larson 1F

What exactly is meant by "TM complex/organometallic complex/coordination compound"? All these refer to the same thing, but we have been mainly using the term coordination compound in class. The terms refer to a central metal atom, usually a transition metal (hence the term TM complex), th...

Jada Larson 1F

Coordination compounds consist of a central metal atom, usually a transition metal with may oxidation states, that is directly bonded to one or more atoms, called ligands. The coordination sphere is made from the ligand(s) directly attached to the central atom or ion.

Jada Larson 1F

A chelate is a ligand that forms a ring with the central metal. It bonds cations very tightly, and an example of one is EDTA.

Jada Larson 1F

I am slightly confused by the previous explanation, which implies that the structure of sigma bonds make them harder to break. It doesn't make sense because single bonds (with a single sigma bond) are weaker than double bonds (with both a sigma bond and pi bond). Could someone explain the relationsh...

Jada Larson 1F

Assuming you are referring to hybridization in relation to chemical bonds, the following is a link to the first of a series of chemistry videos on hybridization and hybrid orbitals on Khan Academy: https://www.khanacademy.org/science/chemistry/chemical-bonds/copy-of-covalent-bonds/v/sp3-hybrid-orbit...

Jada Larson 1F

I believe we are expected to know the following exceptions to the octet rule:

H, He can only hold only 2 electrons
B, Al can only hold 6 electrons
P holds up to 10 electrons
S holds up to 12 electrons
Elements with a d-orbital can hold more electrons than the octet rule.

Let me know if I missed any!

Jada Larson 1F

Yes, for the purpose of our class, the names dispersion, induced dipole-induced dipole, London, and Van der Waals can be used interchangeably to describe the fluctuating electron distribution that results in fluctuating dipoles. The term "induced dipole-induced dipole" is the most descript...

Jada Larson 1F

Since a difference greater than 2 forms an ionic bond and a difference less than 1.5 forms a covalent bond, what would you do if the difference in electronegativity is between 1.5 and 2?

Jada Larson 1F

Resonance hybrids can be indicated by drawing dotted lines for the different possible double/triple bonds of the molecule that can be moved.

Jada Larson 1F

Tarek Abushamma wrote:Also be mindful of exceptions, like oxygen, which has a lower ionization energy than nitrogen, yet is not in the center for the lewis dot of NO3.

Why does Oxygen have a lower ionization energy than Nitrogen? I am confused.

Jada Larson 1F

Instead of calculating the formal charge, could one simply make sure that all the atoms have the correct number of valence electrons ? or would this not work all the time? I believe that method would not work all of the time because some elements violate the octet rule. For instance, phosphorous ho...

Jada Larson 1F

The structure with the formal charge closest to zero is the most stable, meaning it has the lowest energy. Hope that helps!

Jada Larson 1F

Elements want the most stable electron configuration possible, so they will lose electrons and be positively charged (cations) or gain electrons and be negatively charged (anions) to become more like the noble gases, which are stable. That is why elements on the left side of the periodic table, like...

Jada Larson 1F

For an electron to transition to a higher energy level, say 1s to 2p, it must be excited by absorbing energy, from say a photon of light, so the energy of the electron does increase. The 1 in 1s and 2 in 2s indicate the principle quantum numbers, n, which represent the energy and size of the orbital...

Jada Larson 1F

For part (d), the problem specifically asks for the total possible electrons with the principle quantum number, n=3, and angular momentum, l=2, and magnetic quantum number, m l =1, which gives the orientation of the orbital in space. Only one orbital can exist in that exact location in space, meanin...

Jada Larson 1F

According to Hund's Rule, due to electron repulsion, electrons in the same sub-shell occupy different orbitals with parallel spin.

Jada Larson 1F

Since subshells correspond to the layout of the periodic table, did the development of both occur during the same time period?

Jada Larson 1F

Do the subshells (s, p, d, and f) correspond to the orbital angular momentum quantum numbers (l=0, 1, 2, 3)?

Jada Larson 1F

The following formula can be also used to find the energy of a photon: E photon = E energy remove electron + E excess E photon = h v [*]where h is planck's constant and v is frequency E energy remove electron is also called the work function or the threshold energy E excess = (1/2)mv 2 [*][*]where v...

Jada Larson 1F

I agree with the previous descriptions. For a more audio-visual answer, Khan academy offers a wonderful explanation of the difference between the wave model and the particle model in a video on de Broglie wavelength. (video: https://www.khanacademy.org/science/physics/quantum-physics/atoms-and-elect...

Jada Larson 1F

How is it possible that photons have momentum if photons do not have a mass and if momentum equals mass time velocity?

Jada Larson 1F

The equation related to threshold energy is: E photon - E required to eject electron = E excess E photon =h v . [*]h = 6.626 x 10 -34 Js and [*]the v is frequency E required to eject electron is called the threshold energy or the work function, and it is represented by the symbol ϕ. E excess equals ...

Jada Larson 1F

As explained to me by an undergraduate assistant, Significant Figures indicate uncertainty in measurements (because inherent error always exist in any tool).

Jada Larson 1F

These are the general rules for sig figs as explained to me by an undergraduate assistant: All non 0s are significant. There are three types of zeros: (a) leading 0s (in beginning) are NEVER significant [i.e., 0.0567 --> 3 Sig Figs] (b) trapped 0s (in middle) are ALWAYS significant [i.e., 2018 --> 4...

Jada Larson 1F

How do you know how many decimals to use? For example, if I had 2.0 moles x 134.6 g, how many decimals should my answer have? If you had 2.0 mol x 134.6 g/mol, your answer should have two decimal places (2.692 g --> 2.7 g). This is because when you multiple or divide, you count the number of Sig Fi...

Jada Larson 1F

In case of calculations that require the usage of values from the periodic table, are we supposed to use the exact value stated or should we round it up? I believe that for calculations that require the usage of values from the periodic table, we should use the exact value stated for the element in...

Jada Larson 1F

Is "M" the most commonly used variable for an unknown element? Or are other letters used as variables? Thanks.

CHEMISTRY COMMUNITY

Search found 31 matches

Re: Ka

Re: CH3COOH vs CH3OH Acid Strength

Re: Polyprotic Question!

Re: Significance of Coordination Number?

Re: Define Ligands?

Re: Ligand and coordination sphere

Re: Chelate

Re: Bond Strength/Bond Type

Re: basics of hybridization

Re: Expanded octects

Re: London Dispersion, Induced dipole- Induced dipole, Van Der Waals

Re: How to tell which elements will be most likely to form a covalent bond

Re: resonance structures on exams

Re: 3.33

Re: Formal charge purpose

Re: hw 3.53

Re: cation or anion?

Re: Energy of electron vs. Energy Level

Re: 2.29

Re: Electron configuration

Re: HW 2.31 [ENDORSED]

Re: Difference between a shell, subshell, and orbital

Re: Finding the Energy of A Photon

Re: Difference between wave model and particle model? [ENDORSED]

Re: still don't uderrsatnd what a photon is [ENDORSED]

Re: Threshold Energy [ENDORSED]

Re: Why are sig figs important?

Re: Sig Figs [ENDORSED]

Re: Sig figures

Re: Sig Figs

Re: E.15 [ENDORSED]