Search found 37 matches

by Mariam Baghdasaryan 4F
Sat Dec 08, 2018 2:24 pm
Forum: Naming
Topic: edta 4-
Replies: 2
Views: 70

edta 4-

If the coordination compound has the ligand ethylenediaminetetraacetato is this written simply as (edta) or (edta 4-) when naming the compound because technically they're two different things?
by Mariam Baghdasaryan 4F
Fri Dec 07, 2018 11:52 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: H20 as ligand
Replies: 1
Views: 51

H20 as ligand

Why is H20 not a bidentate even though it has 2 lone pairs?
by Mariam Baghdasaryan 4F
Fri Dec 07, 2018 11:31 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligand
Replies: 1
Views: 44

Ligand

Do have to memorize all of these ligands?
by Mariam Baghdasaryan 4F
Sun Dec 02, 2018 7:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Question 4.91 Part B (Sixth Edition)
Replies: 1
Views: 81

Re: Question 4.91 Part B (Sixth Edition)

The two carbons that don't have an H attached to them have an sp hybridization, so they would want to have the linear arrangement. But because the atoms are arranged to form a ring, the two carbons have a strained structure (meaning they won't form 180 degree angles). This is why it is reactive.
by Mariam Baghdasaryan 4F
Sun Dec 02, 2018 7:22 pm
Forum: Student Social/Study Group
Topic: Fall 2018 Final
Replies: 1
Views: 278

Re: Fall 2018 Final

I don't think so, but I would check with your T.A.
by Mariam Baghdasaryan 4F
Wed Nov 28, 2018 6:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral
Replies: 2
Views: 58

Tetrahedral

Does a tetrahedral like CH4 have 5 109.5 degree bond angles?
by Mariam Baghdasaryan 4F
Sat Nov 24, 2018 1:08 pm
Forum: Bond Lengths & Energies
Topic: Determining Higher Boiling Points
Replies: 2
Views: 86

Re: Determining Higher Boiling Points

It is true that the H-Br bond length is shorter than the H-I bond length. However, what you need to consider is also the size of the atoms. I is a larger atom than Br, so it has more electrons that increase the strength of the dispersion forces and the attractive interactions. Due to the greater att...
by Mariam Baghdasaryan 4F
Sat Nov 24, 2018 12:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VESPR Geometric Shapes
Replies: 1
Views: 67

Re: VESPR Geometric Shapes

Trigonal Bipyramidal: AX5
Seesaw: AX4E
Square Pyramidal: AX5E

A represents the central atom
X bonded atom
E lone pair

Notice how they are not exactly the same because of the lone pairs.
by Mariam Baghdasaryan 4F
Sat Nov 24, 2018 12:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw bond angles
Replies: 3
Views: 118

Re: Seesaw bond angles

There are two 90 degree lone-pair-bonding-pair repulsions, but I am not sure about the number of 120 degree bond angles.
by Mariam Baghdasaryan 4F
Sat Nov 17, 2018 7:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: End-to-end vs. Side-to-side
Replies: 2
Views: 76

Re: End-to-end vs. Side-to-side

Professor Lavelle drew the p-p orbitals on the board which helped me visualize this. Note that a p-orbital has 2 lobes. For the "end-to-end," if p-orbital 1 and p-orbital 2 are in the horizontal direction next to each other, the "end" of the right lobe of p-orbital 1 will "o...
by Mariam Baghdasaryan 4F
Sat Nov 17, 2018 6:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 16
Views: 238

Re: Bond Angles

I believe that Professor Lavelle said we don't need to know the exact bond angles for specific molecules, but we should know it for the general shape. So if you identify a molecule to have the trigonal pyramidal shape (3 bonding pairs and 1 lone pair), you can say that the bond angles for that molec...
by Mariam Baghdasaryan 4F
Fri Nov 16, 2018 1:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion Strength
Replies: 2
Views: 53

Repulsion Strength

Why is lone-lone pair repulsion stronger than lone-bonding pair and bonding-bonding pair?
by Mariam Baghdasaryan 4F
Sat Nov 10, 2018 7:35 pm
Forum: Bond Lengths & Energies
Topic: Energy of Intermolecular forces
Replies: 2
Views: 89

Energy of Intermolecular forces

In our lecture notes, the energy is negative i.e. for ion-ion it is -250 kJ/mol, but in the book all the values are positive. Why is this?
by Mariam Baghdasaryan 4F
Sat Nov 10, 2018 5:29 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Character
Replies: 1
Views: 91

Re: Covalent Character

Something like NaCl is known to be a salt with an ionic bond between Na+ and Cl-. You have to keep in mind though that all ionic bonds have covalent character, meaning electrons are going to be "shared" between the Na+ and Cl-. The Na+ which is the cation has polarizing power and can exert...
by Mariam Baghdasaryan 4F
Sat Nov 10, 2018 5:18 pm
Forum: Resonance Structures
Topic: Expanded Octet and Resonance
Replies: 2
Views: 111

Re: Expanded Octet and Resonance

I don't think it can because if it has more than 4 single bonds, then that means the central atom has more than 8 valence electrons, already suggesting an expanded octet. The resonance structures also have to reflect this. If an atom does not have a d-orbital or f-orbital for more electrons, it can'...
by Mariam Baghdasaryan 4F
Tue Nov 06, 2018 10:42 pm
Forum: Administrative Questions and Class Announcements
Topic: HW for this week
Replies: 2
Views: 126

HW for this week

Which HW problems can we turn in this week? 3.73 and onward, or are all chapter 3 problems acceptable?
by Mariam Baghdasaryan 4F
Sun Nov 04, 2018 5:17 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge SO42-
Replies: 3
Views: 1126

Re: Formal Charge SO42-

Thank you that makes sense!
by Mariam Baghdasaryan 4F
Sun Nov 04, 2018 4:07 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge SO42-
Replies: 3
Views: 1126

Formal Charge SO42-

The more stable structure of SO42- has 2 double bonds and 2 single bonds with O, but the single bonds have a formal charge of -1. Why can't those single bonds also become double bonds so that the formal charge becomes 0. Since S can accommodate more than 8 valence electrons, wouldn't this work?
by Mariam Baghdasaryan 4F
Sun Nov 04, 2018 12:39 am
Forum: Trends in The Periodic Table
Topic: Isoelectronic elements
Replies: 1
Views: 55

Isoelectronic elements

So In is [Kr] 4d10 5s2 5p1. So for In3+, I looked at the periodic table and moved 3 to the left, arriving at Palladium. Hence, I thought the electron configuration of palladium/In 3+ will be [Kr] 4d8 5s2, but palladium is an exception like chromium and copper so its electron configuration is [Kr] 4d...
by Mariam Baghdasaryan 4F
Sat Nov 03, 2018 11:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons
Replies: 2
Views: 62

Valence Electrons

Do we need to know the # of valence electrons for the 3d elements?
by Mariam Baghdasaryan 4F
Sat Nov 03, 2018 10:16 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Subshells
Replies: 2
Views: 61

Subshells

For example, the electron configuration for Selenium (Se) is [Ar] 3d10 4s2 4p4.

If I am looking at n=4, then l can be the 0 (s) ,1 (p), 2 (d) and 3 (f) subshells. Since Selenium goes up to 4p4, does that mean it has empty l=2 and l=3 subshells, or does it not have those subshells at all?
by Mariam Baghdasaryan 4F
Wed Oct 31, 2018 10:21 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation Numbers
Replies: 3
Views: 130

Re: Oxidation Numbers

Step 1. Atoms in their elemental state have an oxidation number of 0. Step 2. Atoms in monatomic (i.e. single atom) ions have an oxidation number equal to their charge. Step 3. In compounds: fluorine is assigned a −1 oxidation number; oxygen is usually assigned a −2 oxidation number (except in perox...
by Mariam Baghdasaryan 4F
Thu Oct 25, 2018 12:18 am
Forum: DeBroglie Equation
Topic: De Broglie module #35
Replies: 3
Views: 145

De Broglie module #35

35. Calculate the wavelength of a 275 kg single-seat electric car traveling at a speed of 125 km.hr-1. Do electric cars have wavelike properties? A. λ = 6.94 x 10-38 m , Yes B. λ = 6.94 x 10-38 m , No C. λ = 1.93 x 10-38 m , Yes D. λ = 1.93 x 10-38 m , No I got the wavelength correct, but I chose A ...
by Mariam Baghdasaryan 4F
Wed Oct 24, 2018 8:03 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Module #37
Replies: 2
Views: 150

Atomic Spectra Module #37

37. Write the equation that allows one to calculate the electronic energy levels for the hydrogen atom. Do the calculated energies compare favorably with empirical observation (spectroscopic results)? C. E = -hR/(n2), No D. E = -hR/(n2), Yes Is the 2nd question asking whether the calculated version ...
by Mariam Baghdasaryan 4F
Tue Oct 23, 2018 10:46 pm
Forum: Photoelectric Effect
Topic: Module: Photoelectric Effect #25
Replies: 1
Views: 134

Module: Photoelectric Effect #25

25. Photoelectric experiments gave rise to a new equation relating the energy of light to its frequency. Select the right equation. A. λv = c B. Ek = mv2/2 C. mv2/2 = hv - φ D. E = hv E. None of the above Is E=hv the correct answer since it is the one that clearly relates energy to the frequency? I ...
by Mariam Baghdasaryan 4F
Wed Oct 17, 2018 11:54 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Absorption/atomic spectra
Replies: 3
Views: 111

Absorption/atomic spectra

If the electron went from a lower energy state (i.e. n to higher energy state that would indicate absorption, so the difference in energy would be positive instead of negative. Would the photon energy still be positive in this case since it is no longer an emission?
by Mariam Baghdasaryan 4F
Wed Oct 17, 2018 11:10 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra
Replies: 1
Views: 48

Atomic Spectra

In the image, why is the photon of particular energy given as v? I understand that v=change in Energy/h, but isn't v the Bohr frequency condition and not "the particular energy"?
by Mariam Baghdasaryan 4F
Wed Oct 17, 2018 10:49 pm
Forum: Photoelectric Effect
Topic: Intensity
Replies: 2
Views: 80

Intensity

In the photoelectric effect, higher intensity does not necessarily mean greater amplitude right? Do we stop treating light like a wave once we consider it a photon?
by Mariam Baghdasaryan 4F
Wed Oct 17, 2018 9:46 pm
Forum: Properties of Light
Topic: Friday 10/5 Lecture
Replies: 7
Views: 135

Friday 10/5 Lecture

Properties of Light: Friday 10/5 Lecture: When Professor Lavelle wrote v=m*s^-1 on the board was he referring to velocity? In my notebook, I wrote v as frequency, but I don't think that makes sense.
by Mariam Baghdasaryan 4F
Wed Oct 10, 2018 11:16 pm
Forum: Significant Figures
Topic: Module: Molarity #15
Replies: 6
Views: 409

Module: Molarity #15

15. Calculate the concentration (molarity) of a glucose solution containing 0.1 moles of glucose in 0.4 liters of water. A. 0.25 mol.L-1 B. 4.0 mol.L-1 C. 2.5 mol.L-1 D. 2 mol.L-1 .1mol/.4L=.25 mol. L-1. So I got this for the answer but I was confused why the answer is exact and not 1 sig fig (.2)
by Mariam Baghdasaryan 4F
Wed Oct 10, 2018 7:49 pm
Forum: Limiting Reactant Calculations
Topic: Module Question #18 Help
Replies: 1
Views: 115

Module Question #18 Help

18. For the following equation, determine the limiting reagent if 21.4 g NH3 is reacted with 42.5 g of O2. 4NH3(g) + 5O2(g) ---> 4NO(g) + 6H2O(g) A. NH3 B. O2 C. Both D. Neither I did this incorrectly the first time, so now I am not sure about my work. Can someone please confirm my work? Based on my...
by Mariam Baghdasaryan 4F
Sun Oct 07, 2018 6:43 pm
Forum: Significant Figures
Topic: Sig Fig in Relation to Zero
Replies: 3
Views: 139

Re: Sig Fig in Relation to Zero

0.0490 has 3 sig figs I read this in another post: "If the decimal point is present, start counting digits from the Pacific (left) side, starting with the first non-zero digit. If the decimal point is absent, start counting digits from the Atlantic (right) side, starting with the first non-zero...
by Mariam Baghdasaryan 4F
Sun Oct 07, 2018 6:29 pm
Forum: Significant Figures
Topic: Empirical and Molecular Formula's Video #19
Replies: 3
Views: 309

Re: Empirical and Molecular Formula's Video #19

The number of significant figures that the answer should have is determined by what is given in the question and not what has been calculated. Therefore, since the molar mass of 84 is the only number that is given, then the answer should have 2 significant figures because 84 has 2 sig figs. If ther...
by Mariam Baghdasaryan 4F
Sat Oct 06, 2018 5:04 pm
Forum: Significant Figures
Topic: Empirical and Molecular Formula's Video #19
Replies: 3
Views: 309

Empirical and Molecular Formula's Video #19

19. The molar mass of cyclohexane is 84 g.mol–1 and its empirical formula is CH2 What is its molecular formula? So I did 1x12.011g.mol^-1+2x1.008g.mol^-1= 14.027g.mol^-1 When I do 84 g.mol–1/14.027g.mol^-1, how many sig figs will the answer have? Is 84 just considered an integer which means that I l...
by Mariam Baghdasaryan 4F
Thu Oct 04, 2018 11:04 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles and Molar Mass
Replies: 10
Views: 137

Re: Moles and Molar Mass

So you are given 1.00 mol of Ag, but what you are supposed to find is the number of Ag atoms from this given info. because only then can you use the radius given (144pm) to figure out how long the fiber is. Step 1: you would convert the mol of Ag to number of Ag atoms 1.00 mol Ag x (6.0221x10^23)/mo...
by Mariam Baghdasaryan 4F
Thu Oct 04, 2018 10:49 pm
Forum: Significant Figures
Topic: Sig Figs
Replies: 3
Views: 122

Sig Figs

If my empirical formula is CH2, for example, and then I need to use the molar mass to find the molecular formula, I do 1(12.011 g.mol^-1)+2(1.008 g. mol^-1). Will my answer have 3 places after the decimal because I am supposed to focus on the addition rule or will it be 4 significant digits because ...
by Mariam Baghdasaryan 4F
Wed Oct 03, 2018 2:19 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Clarification on Units (Moles)
Replies: 1
Views: 76

Re: Clarification on Units (Moles)

I think the book defines N as "# of objects" because a "mole" is the amount of substance and that substance is Cu in your video. The objects that make up a substance can be atoms, molecules, ions, etc. In most examples, the "objects" are the atoms, so N is the # of atom...

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