Search found 35 matches

by Melody Zhang 3L
Tue Dec 04, 2018 11:01 pm
Forum: Bronsted Acids & Bases
Topic: Proton transfer
Replies: 1
Views: 89

Proton transfer

For question 12.9 pt.C, 6th edition, how come there is no proton transfer from CH3COOH --> CH3CONH2?
by Melody Zhang 3L
Tue Dec 04, 2018 12:09 am
Forum: Conjugate Acids & Bases
Topic: Writing Ion Formulas
Replies: 1
Views: 72

Re: Writing Ion Formulas

It is because F is the one with the negative charge and is able to bind with the H+ atom
by Melody Zhang 3L
Tue Dec 04, 2018 12:05 am
Forum: Naming
Topic: Do we need to know en, edta?
Replies: 2
Views: 78

Do we need to know en, edta?

Do we need to know specifically what oxalato, en, dien, and edta stand for and their molecular formulas, or just their denticity?
by Melody Zhang 3L
Mon Dec 03, 2018 11:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis Structure for I3-
Replies: 1
Views: 486

Lewis Structure for I3-

Iodine has 7 valence electrons, so at first, I allocated 3 lone pairs around each of the Iodines, with the central iodine having a formal charge of -1. However, I realized that I was taught to place the negative charge on the outside atoms whenever possible, so I made one of the lone pairs of the ce...
by Melody Zhang 3L
Tue Nov 27, 2018 11:52 pm
Forum: Dipole Moments
Topic: Drawing dipole moments
Replies: 3
Views: 84

Drawing dipole moments

I just wanted to clarify in a lewis structure whether we should draw the arrows pointing to the positive or negative dipole? In my notes from the lecture, I drew the arrows pointing to the negative dipole, but I think the textbook prefers drawing the arrow pointing to the positive dipole.
by Melody Zhang 3L
Tue Nov 27, 2018 11:19 pm
Forum: Ionic & Covalent Bonds
Topic: Strength of covalent bonds
Replies: 2
Views: 73

Re: Strength of covalent bonds

sorry I meant based on electronegativity, CF4 should be the weakest
by Melody Zhang 3L
Tue Nov 27, 2018 11:18 pm
Forum: Ionic & Covalent Bonds
Topic: Strength of covalent bonds
Replies: 2
Views: 73

Strength of covalent bonds

For #87, Chapter 3, 6th edition, why does CF4 have the strongest bond? Based on electronegativity, the strength of CF4 should be the strongest right?
by Melody Zhang 3L
Tue Nov 27, 2018 4:31 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 1
Views: 274

Resonance Structures

For 6th edition CH3 #43, is there an easier way to identify all the resonance structures of the molecule?
by Melody Zhang 3L
Wed Nov 21, 2018 1:49 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Difference between O2- and N3-
Replies: 3
Views: 150

Re: Difference between O2- and N3-

Actually, I just searched it up and it says that 02 is more polarizable than n3 because 02 is larger than n3
by Melody Zhang 3L
Wed Nov 21, 2018 1:45 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Difference between O2- and N3-
Replies: 3
Views: 150

Re: Difference between O2- and N3-

Polarizability does depend on both the charge and the atomic radius, and it increases as atomic radius increases and charge decreases. In this case, I believe N3- is more polarizable because there was a greater difference between atomic radii.
by Melody Zhang 3L
Wed Nov 21, 2018 1:36 pm
Forum: Hybridization
Topic: Using hybrid orbitals
Replies: 2
Views: 56

Re: Using hybrid orbitals

It isn't necessary but 2sp3 is more specific because it is the second shell.
by Melody Zhang 3L
Wed Nov 21, 2018 1:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing out Molecular Shape
Replies: 3
Views: 93

Drawing out Molecular Shape

Do we need to draw out the dashed line and bold line when asked to draw the lewis structure?
by Melody Zhang 3L
Thu Nov 15, 2018 7:31 pm
Forum: Electronegativity
Topic: Is it best to memorize electronegativity?
Replies: 8
Views: 391

Re: Is it best to memorize electronegativity?

I assume there examples we will be given will have molecules with atoms of obviously different electronegativity, for example NH3 or H2O and we're not expected to know the exact electronegativity.
by Melody Zhang 3L
Thu Nov 15, 2018 7:26 pm
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 6
Views: 126

Re: Dipole Moments

Dipole moments are the measurements of the separation of two opposite electric charges, for example the charge of H and the charge of O in the molecule H2O. Nonpolar molecules have very small or no dipole moments while polar molecules have a higher dipole moment.
by Melody Zhang 3L
Thu Nov 15, 2018 7:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shapes
Replies: 3
Views: 92

Re: Molecular shapes

You can think of 5 atoms surrounding a central atom as composed of two pyramids, so it's trigonal bipyramid, three atoms surrounding one central atom as a flat molecule, so it is trigonal planar. When you see tetrahedral, just think of 4 surrounding atoms because tetra=4
by Melody Zhang 3L
Mon Nov 05, 2018 11:36 pm
Forum: Lewis Structures
Topic: Identifying the element
Replies: 8
Views: 190

Identifying the element

For the sixth edition chapter 3 #37, when given a lewis structure and asked to identify the element in the center, can we just explain our answer by saying that only an element with 5 valence electrons would make the formal charge 0, and the only element in period 3 with 5 valence electrons is Phosp...
by Melody Zhang 3L
Mon Nov 05, 2018 11:31 pm
Forum: Ionic & Covalent Bonds
Topic: Identifying compounds
Replies: 2
Views: 65

Identifying compounds

Would we need to know how to identify compounds such as ammonium chloride and draw the lewis structure without knowing the formula? I also had trouble figuring out which bonds were covalent and which were ionic without seeing the charges on the formula. (NH4+ CL-)
by Melody Zhang 3L
Mon Nov 05, 2018 11:20 pm
Forum: Lewis Structures
Topic: BH4-
Replies: 2
Views: 141

BH4-

How would one draw this lewis structure? I thought we were not supposed to place the negative formal charge on the central atom.
by Melody Zhang 3L
Wed Oct 31, 2018 11:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Filling of Orbitals
Replies: 3
Views: 143

Re: Filling of Orbitals

The same idea does apply to the 5s orbital, and it is filled before 4d. However, there is no 4f electron configuration for period five, as 4f1 begins after lanthanum. I don't think we need to know the specific patterns of period 5, like why it is 4d4 5s1 instead of 4d3 5s2, just be able to count the...
by Melody Zhang 3L
Tue Oct 30, 2018 8:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Config for period 5
Replies: 2
Views: 56

Electron Config for period 5

Does anyone know if we need to memorize the patterns for electron configuration for period 5 and below? They differ from the exceptions in period 4, like chromium is 3d5 4s1 instead of 3d4 4s2, because in period 5, niobium is 4d45s1 instead of 4d3 5s2.
by Melody Zhang 3L
Mon Oct 29, 2018 11:51 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: How to write electron config for Bi3+?
Replies: 1
Views: 141

How to write electron config for Bi3+?

For the hw problem, 3.5 part b, the ground state electron configuration for Bi3+ was 4f14, 5d10, 6s2. I thought it would be just 6s2 because the electron configuration of Bi is 6s2, 6p3. Can someone clarify where the 4f14 and 5d10 came from?
by Melody Zhang 3L
Wed Oct 24, 2018 10:55 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Q. 1.57
Replies: 2
Views: 108

Re: Q. 1.57

The two are essentially the same but I think we need to use En=-hR/n^2 for the class.
by Melody Zhang 3L
Wed Oct 24, 2018 10:52 pm
Forum: *Shrodinger Equation
Topic: Solutions to the Schrodinger Equation
Replies: 1
Views: 236

Re: Solutions to the Schrodinger Equation

The wave function is a function that varies depending on the position of the particle. Using the Schrodingers equation we can find the wave function and the energy. I don't think we need to know the equation for the class.
by Melody Zhang 3L
Wed Oct 24, 2018 10:48 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron Configurations
Replies: 3
Views: 74

Electron Configurations

I understand why we use the noble gases to write the shorthand version of the electron configuration for say the element Chromium, but I'm not sure how we're supposed to know exactly what number to start on after. For example, Chromium is [Ar] 3d5 4s1, but how do we know to start on 3d?
by Melody Zhang 3L
Tue Oct 16, 2018 9:17 pm
Forum: *Black Body Radiation
Topic: Stefan-Boltzmann law and Wien's law
Replies: 2
Views: 276

Stefan-Boltzmann law and Wien's law

I'm confused. Have we ever covered the Boltzmann law or Wien's law in class? If not will we need to review on our own?
by Melody Zhang 3L
Tue Oct 16, 2018 9:00 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Incorrect Atomic Model
Replies: 6
Views: 141

Re: Incorrect Atomic Model

Delta v is the amount of uncertainty in the electron's velocity. Because the uncertainty was greater than the speed of light and was an unrealistic number, it proves that electrons do not collapse to the nucleus.
by Melody Zhang 3L
Tue Oct 16, 2018 8:54 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Formulas?
Replies: 2
Views: 91

Formulas?

Can anyone clarify which equations we need to know? I'm kind of lost with the Rydberg expression v=R(1/n21-1/n22), Weins Law, and the Bohr Frequency condition: hv=E(upper)-E (lower).
by Melody Zhang 3L
Wed Oct 10, 2018 7:42 pm
Forum: Properties of Light
Topic: Light
Replies: 9
Views: 169

Re: Light

The amplitude is the height of the wave and it corresponds with he intensity of the light. I don't believe amplitude is related to frequency because the intensity of light is different from the energy of each photon, which is related to the wavelength and frequency.
by Melody Zhang 3L
Wed Oct 10, 2018 7:39 pm
Forum: Properties of Light
Topic: Problem 1.23
Replies: 2
Views: 41

Re: Problem 1.23

The reason the textbook used the 6.62608 x 10-34 Js was to match the number of sigfigs given (140.511 keV). If the given number has less sigfigs, I believe you can use 6.63 x 10-34 Js.
by Melody Zhang 3L
Wed Oct 10, 2018 5:41 pm
Forum: Properties of Light
Topic: Problem number 1.23 [ENDORSED]
Replies: 3
Views: 75

Problem number 1.23 [ENDORSED]

Does anyone know how to convert from keV to joules?
by Melody Zhang 3L
Thu Oct 04, 2018 6:06 pm
Forum: Molarity, Solutions, Dilutions
Topic: Q G17 part b. (7th edition)
Replies: 5
Views: 122

Re: Q G17 part b. (7th edition)

Yes, you add the molar mass of 5H2O to the molar mass of CuSO4 to find the amount in grams of CuSO4*5H2O needed and multiply that with the amount in moles of CuSO4 (0.20mol/L)(.250L).
by Melody Zhang 3L
Thu Oct 04, 2018 5:45 pm
Forum: Empirical & Molecular Formulas
Topic: Converting from mole ratios to empirical formula
Replies: 2
Views: 91

Converting from mole ratios to empirical formula

For problem F9 (sixth edition), how is the ratio 1 oxygen 2.67 hydrogen and 2.67 carbon converted to the empirical formula C8H8O3? I understand that the ratio is multiplied by three but I don't see how to tell what multiple to multiply the ratio with.
by Melody Zhang 3L
Thu Oct 04, 2018 5:31 pm
Forum: Empirical & Molecular Formulas
Topic: HW 1 Problem F.9
Replies: 7
Views: 126

Re: HW 1 Problem F.9

I believe they are asking you to find the empirical formula after you find the mole ratio of the compound.

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