Search found 37 matches

by Bryan Jiang 1F
Sat Jun 09, 2018 11:43 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Porphyrin Ligand
Replies: 4
Views: 163

Re: Porphyrin Ligand

The porphyrin ligand was the tetradentate structure with four N surrounding the Fe atom.
by Bryan Jiang 1F
Sat Jun 09, 2018 11:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of AX5E
Replies: 5
Views: 238

Re: Shape of AX5E

I think it is the very fact that the lone pair pushes the four bonded atoms down that creates the pyramidal shape. Of course, there is an additional axial/vertical bonded atom pointing down too, but the most characteristic feature of AX5E would be the depressed four bonded atoms from the lone pair.
by Bryan Jiang 1F
Sat Jun 09, 2018 10:59 pm
Forum: Empirical & Molecular Formulas
Topic: E3
Replies: 2
Views: 156

Re: E3

You have the right reasoning but just the wrong information. There was a figure associated with the question which explains why the answer is 3 At atoms.

059BB7FB-98AE-46CE-957D-718C0849A5C7.jpeg


Left: 9 Ga (9 x 70 g/mol = 630 g/mol)
Right: 210 g/mol x 3 At = 630 g/mol

Answer: 3 At
by Bryan Jiang 1F
Sat Jun 09, 2018 10:51 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron configuration of Palladium
Replies: 2
Views: 171

Re: electron configuration of Palladium

The exception is probably just palladium. Because exceptions to exceptions become more prominent down the periods, Dr. Lavelle wants us to focus on just up to the first row of transition metals where the exceptions are regular. This means that we are not expected to know the exceptions to exceptions...
by Bryan Jiang 1F
Sun Jun 03, 2018 11:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 6
Views: 162

Re: Molecular Shape

Not only every atom, but also lone pairs. Both a bound atom and a lone pair are each referred to as an electron density region. So it is like a rule of thumb that every region of electron density should be as far from the other in determining the molecular shape, which takes up 3-dimensional space.
by Bryan Jiang 1F
Sun Jun 03, 2018 11:04 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelate
Replies: 2
Views: 104

Re: Chelate

A chelate is a structure resembling a ring that results when a special ligand associates with a central atom, usually a cation. So, it is a complex made of two parts: 1. An atom, usually a cation, that will become the central atom once it is bound by the second part of the complex, the chelating lig...
by Bryan Jiang 1F
Sun Jun 03, 2018 10:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSPER MODEL FOR IODINE TRICHLORIDE
Replies: 2
Views: 118

Re: VSPER MODEL FOR IODINE TRICHLORIDE

For iodine trichloride, the VSEPR formula I got was AX3E2. The iodine is the central atom and has bonds with three chlorine. With 28 electrons to use, you should end up with two remaining lone pairs. I am do not think this shape was taught in lecture, but the shape is T-shaped.
by Bryan Jiang 1F
Tue May 22, 2018 11:53 pm
Forum: Dipole Moments
Topic: Correct Dipole Depiction
Replies: 4
Views: 256

Re: Correct Dipole Depiction

In lecture, it seems that the original convention (arrow pointing towards the partial negative charge) was used. However, I think Dr. Lavelle made a comment that in physics, the arrow pointing toward the partial positive charge is common.
by Bryan Jiang 1F
Tue May 22, 2018 11:29 pm
Forum: Lewis Structures
Topic: Carbon Monoxide Lewis Structure
Replies: 3
Views: 183

Re: Carbon Monoxide Lewis Structure

Yes, since for one of the bonds in the triple bond the oxygen provides two electrons, this makes it a coordinate covalent bond between the carbon and oxygen in CO.
by Bryan Jiang 1F
Tue May 22, 2018 7:02 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: self-test 3.13B
Replies: 1
Views: 189

Re: self-test 3.13B

So as you said, both CaO and CaS have the same polarizing cation, Ca2+. The reason that CaS would have a greater covalent character than CaO would thus be attributed to the different polarized anions. S2- will be larger than O2- by one outer shell. This makes the electron cloud of S2- be more vulner...
by Bryan Jiang 1F
Mon May 14, 2018 5:31 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 4
Views: 139

Re: Covalent Bonds

I think it’s also important to remember that this is just a guideline. Finding formal charges might be the best way to determine which atom should be the central atom. Consider the case for ONF (from problem 3.33). Although oxygen technically has the lowest ionization energy of the three elements, i...
by Bryan Jiang 1F
Mon May 14, 2018 5:12 pm
Forum: Trends in The Periodic Table
Topic: Does Sulfur or Phosphorus have a larger ionization energy?
Replies: 3
Views: 808

Re: Does Sulfur or Phosphorus have a larger ionization energy?

I think that sulfur has a higher ionization energy because generally ionization energy increases across the periodic table. You are right in that ionization energy generally increases across a period, but only generally . For the case between phosphorus and sulfur, phosphorus would actually have th...
by Bryan Jiang 1F
Mon May 14, 2018 4:32 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity
Replies: 5
Views: 181

Re: Electronegativity

One would have to look at properties other than electronegativity difference to tell what kind of bond is present.
by Bryan Jiang 1F
Sun May 13, 2018 12:38 am
Forum: Ionic & Covalent Bonds
Topic: Why can't hydrogen be a central atom? [ENDORSED]
Replies: 6
Views: 291

Re: Why can't hydrogen be a central atom? [ENDORSED]

In addition to only having one electron, hydrogen also only has one orbital, the 1s orbital. So once hydrogen is sharing electrons with another atom, this one orbital that hydrogen has will be used up for this sharing. Any additional atom that wants to share electrons with this hydrogen cannot do so...
by Bryan Jiang 1F
Sun May 13, 2018 12:08 am
Forum: Ionic & Covalent Bonds
Topic: radicals [ENDORSED]
Replies: 9
Views: 248

Re: radicals [ENDORSED]

sharonvivianv wrote:They are electrons that are not used while making bonds

I don’t think that is totally true. Lone pairs also are electrons that are not used “while making bonds.” But radicals are more specific, like what Emily said above, that radicals involve a single, unpaired valence electron.
by Bryan Jiang 1F
Wed May 09, 2018 12:33 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Module Questions 21 and 22
Replies: 1
Views: 166

Re: Module Questions 21 and 22

I calculated the answers to be D and A respectively. 21. ΔpΔx ≥ h/4π. Heisenberg’s Indeterminancy Equation. Δx = 2.5 x 10^-10 m. Given. Δp(2.5 x 10^-10) ≥ h/4π. Plug Δx into Heisenberg’s Indeterminancy Equation. Δp ≥ 2.1 x 10^-25 kg.m.s^-1. Answer as electron’s uncertainty in momentum. ——— Δp = mΔv....
by Bryan Jiang 1F
Tue May 01, 2018 3:30 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm Topics [ENDORSED]
Replies: 33
Views: 1759

Re: Midterm Topics [ENDORSED]

The following is from a response from another topic:
Chem_Mod wrote:The midterm will cover everything until end of ch2.
by Bryan Jiang 1F
Tue May 01, 2018 1:43 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: The order for s,p,d
Replies: 3
Views: 125

Re: The order for s,p,d

Electron configuration should be ordered primarily by increasing order of shells, the principle quantum number n. Given this, we also know that when we start including the d-orbitals in the electron configuration, the highest shell in which the d-orbitals reside in “lags” behind the highest shell in...
by Bryan Jiang 1F
Tue May 01, 2018 1:16 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Orders?
Replies: 2
Views: 115

Re: Electron Configuration Orders?

Even though the same information about the electron configuration is displayed by both of those ways, one should still order the electron groupings by n-values first to denote the fact that the shells are the primary differences in energy levels. Dr. Lavelle mentions this preference for n-value orde...
by Bryan Jiang 1F
Sun Apr 29, 2018 11:36 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spin Direction [ENDORSED]
Replies: 4
Views: 229

Spin Direction [ENDORSED]

When we draw out an electron diagram, we indicate the first electrons in orbitals with the up arrow first. Does this imply that all electrons prefer to spin one way (the up arrow spin, counterclockwise) when occupying an orbital by itself?
by Bryan Jiang 1F
Sun Apr 29, 2018 11:08 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Quiz #2 Question #2 B
Replies: 5
Views: 245

Re: Quiz #2 Question #2 B

I believe that moving from n=5 to n=3 takes up more energy which makes the wavelength smaller, less frequency When electrons are dropping from higher energy levels to lower energy levels, energy is RELEASED as a photon, not taken up. Since the drop from n=5 to n=3 is larger than the drop from n=4 t...
by Bryan Jiang 1F
Sun Apr 29, 2018 10:28 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Balmer and Lyman Series
Replies: 9
Views: 562

Re: Balmer and Lyman Series

Yes we need to know the different energy levels for the balmer (n=2) and lyman (n=1) series. I think that it is also important to know that there are only 7 different energy levels. What do you mean by what you said that there are only 7 different energy levels? I thought the number of energy level...
by Bryan Jiang 1F
Sun Apr 22, 2018 11:53 pm
Forum: Administrative Questions and Class Announcements
Topic: Test Time
Replies: 6
Views: 266

Re: Test Time

It felt pretty short since I practiced problems with unlimited time. I think next time I’ll try to practice under time pressure.
by Bryan Jiang 1F
Sun Apr 22, 2018 11:50 pm
Forum: Einstein Equation
Topic: de brogile equation
Replies: 4
Views: 323

Re: de brogile equation

Yes, anything with momentum has a wavelength, including cars. The example of a car I think was used to demonstrate that literally anything with momentum has a wavelength, but the scales where finding this wavelength is more relevant is when talking about particles.
by Bryan Jiang 1F
Sun Apr 22, 2018 11:45 pm
Forum: Einstein Equation
Topic: finding frequency from Einstein's equation [ENDORSED]
Replies: 3
Views: 176

Re: finding frequency from Einstein's equation [ENDORSED]

λ = h/p, then
λ = c/ν —> ν = c/λ gives you frequency.
by Bryan Jiang 1F
Sun Apr 22, 2018 11:39 pm
Forum: DeBroglie Equation
Topic: Wavelength= (h/p) [ENDORSED]
Replies: 7
Views: 326

Re: Wavelength= (h/p) [ENDORSED]

You are correct. λ=h/p cannot apply to light because light does not have mass. As a consequence, photons also have no mass.
by Bryan Jiang 1F
Sun Apr 22, 2018 11:29 pm
Forum: Properties of Light
Topic: Homework #1.7 [ENDORSED]
Replies: 2
Views: 114

Re: Homework #1.7 [ENDORSED]

This is more of a question with sigfigs. Since we have not formally talked about sigfigs in lecture, I do not think the rounding matters for now. Also, be careful of the negative signs in your exponents!
by Bryan Jiang 1F
Sun Apr 22, 2018 11:25 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Balmer and Lyman Series
Replies: 9
Views: 562

Re: Balmer and Lyman Series

It would help to know what energy levels are associated with what part of the EM spectrum. So in the problem you mentioned, recognizing a wavelength of 102.6 nm as being ultraviolet light, and knowing that ultraviolet light is associated with the n=1 energy level (Lyman series) would be really helpf...
by Bryan Jiang 1F
Sun Apr 22, 2018 11:13 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Memorizing spectrum
Replies: 5
Views: 152

Re: Memorizing spectrum

Continuing on with what Jimmy shared, how the order relates to frequency and wavelength, think of the “rays” end of the EM spectrum (x-rays and gamma rays) as being dangerous and thus high energy. A higher frequency/shorter wavelength will correspond to higher energy. So, as you approach gamma rays,...
by Bryan Jiang 1F
Sun Apr 22, 2018 10:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectroscopy [ENDORSED]
Replies: 1
Views: 96

Re: Atomic Spectroscopy [ENDORSED]

What spectroscopic series an energy transition belongs to depends on what energy level an electron jumps from when absorbing energy or what energy level an electron drops to when emitting energy. So for an H-atom, if an electron jumps from or drops to the n=1 energy level, these lines will be of the...
by Bryan Jiang 1F
Sun Apr 15, 2018 6:33 pm
Forum: Photoelectric Effect
Topic: Planck's Constant
Replies: 4
Views: 199

Re: Planck's Constant

In the context of E=hv, h tells us how E and v relate to each other. We know that E and v are proportional in some way, and through experiments, scientists were able to find that E and v relate to each other by h. I think of it as like a ratio. If we imagine in some imaginary universe that E and v r...
by Bryan Jiang 1F
Sun Apr 15, 2018 6:23 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical and Molecular the same [ENDORSED]
Replies: 3
Views: 165

Re: Empirical and Molecular the same [ENDORSED]

In the case you mentioned, yes, the molecular formula and empirical formula would be the same. You can tell if a molecular formula is also the empirical formula if you cannot further simplify the molecular formula to lower whole number ratios.
by Bryan Jiang 1F
Sun Apr 15, 2018 6:00 pm
Forum: Photoelectric Effect
Topic: Video module worked example [ENDORSED]
Replies: 1
Views: 81

Re: Video module worked example [ENDORSED]

Yes, you should still get the same answer. Be careful though, make sure the energy required to remove an electron is 3.61 X 10^-19 J (negative 19, not positive 19). I don’t know if that was the source of your error, but I tried calculating the way you mentioned and still ended up with 551nm both way...
by Bryan Jiang 1F
Sun Apr 15, 2018 1:12 pm
Forum: Photoelectric Effect
Topic: When photon energy is less than threshold energy
Replies: 2
Views: 93

When photon energy is less than threshold energy

I understand that when the energy of photon is less than the threshold energy, no electron will be emitted no matter the rate and how many photons of that same energy hits the electron. My question is wanting to know where the energy of the photons go. Perhaps it dissipates as heat, but I don’t know...
by Bryan Jiang 1F
Sun Apr 08, 2018 8:22 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Accuracy vs Precision
Replies: 23
Views: 700

Re: Accuracy vs Precision

I remember the example we used in class, but I am unsure how to tell which is which. One is when all measurements are close together, but not the desired amount? The other is when all the measurements are on target? Accuracy means how close your measurements are to the true/correct value . Precisio...
by Bryan Jiang 1F
Sun Apr 08, 2018 7:10 pm
Forum: Significant Figures
Topic: 300 vs 300. [ENDORSED]
Replies: 8
Views: 518

Re: 300 vs 300. [ENDORSED]

so the decimal is what sig figs revolves around correct? aka when in doubt just look and see the importance of a decimal? Yes, it could help thinking of sig figs like that when looking for the decimal and the numbers that come before it. However, keep in mind situations where numbers only come afte...
by Bryan Jiang 1F
Sun Apr 08, 2018 5:41 pm
Forum: Limiting Reactant Calculations
Topic: Actual Yield [ENDORSED]
Replies: 3
Views: 114

Re: Actual Yield [ENDORSED]

I believe that the actual yield must always be given since multiple factors (side reactions, impurities, sticking to side of beaker, etc.) can affect how much product the reaction will actually yield. Even if there were a way to calculate actual yield from taking into account every possible variable...

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