Search found 30 matches
- Tue Jun 12, 2018 6:49 pm
- Forum: Lewis Acids & Bases
- Topic: HW 12.17 [ENDORSED]
- Replies: 4
- Views: 486
Re: HW 12.17 [ENDORSED]
I don't understand why SO3 is acidic. I don't see why it would accept protons. Doesn't it already have -2 charge?
- Tue Jun 12, 2018 10:39 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: HW 17.33
- Replies: 6
- Views: 486
Re: HW 17.33
Ligands are more likely to be polydentate if there are many atoms between the ones with lone pairs. This allows the molecule to bend, interacting with the metal in more than one place. Also, I think one reason CO3 2- can't be tridentate is due to its double bond, which would make it harder for the m...
- Sun Jun 03, 2018 12:52 pm
- Forum: Hybridization
- Topic: List of the different shapes
- Replies: 6
- Views: 478
- Sun Jun 03, 2018 12:49 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: formal charge and VSEPR
- Replies: 8
- Views: 511
Re: formal charge and VSEPR
VSEPR refers to the notation and also the way of finding the molecular shape from the Lewis structure.
- Sun Jun 03, 2018 12:46 pm
- Forum: Hybridization
- Topic: σ bonds
- Replies: 9
- Views: 505
Re: σ bonds
Remember how the p-orbitals are oriented: one along the x-axis, one along the y-axis, and one along the z-axis. Because of this orientation, only one of the bonds can overlap the orbitals and be a sigma bond. The other orbitals are side-by-side and therefore form pi bonds. <img src="https://d2g...
- Sun Jun 03, 2018 12:40 pm
- Forum: Hybridization
- Topic: Hybridization and it's relation to valence electrons
- Replies: 3
- Views: 217
Re: Hybridization and it's relation to valence electrons
So if there's a double bond, and 2 single bonds on carbon, the hybridization would be sp2? How does that work in respect to valence electrons?
- Sun May 27, 2018 6:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 2
- Views: 223
Re: Polarity
You have to look at the electronegativity of each element involved. Technically, every covalent bond has polarity unless it is between 2 of the same elements (O2 for example). However, some bonds are more polar (example: C-H bonds are less polar than O-H bonds) due to the differences in electronegat...
- Sun May 27, 2018 6:56 pm
- Forum: Lewis Structures
- Topic: 2 lone pairs
- Replies: 5
- Views: 322
Re: 2 lone pairs
Remember that a Lewis Structure is just a 2D model of a 3D shape. So for example, in water, with a tetrahedral shape, every region of electron density is next to every other, so there is no "top" or bottom. With Lewis structures, it doesn't matter where you draw the lone pairs because it d...
- Sun May 27, 2018 10:11 am
- Forum: Bond Lengths & Energies
- Topic: 3.85 part b
- Replies: 3
- Views: 291
Re: 3.85 part b
Both Lewis structures have one double bonded O and the other(s) are single bonded. Because of resonance, the double bonds are shared throughout the molecule. This makes the bond lengths approximately equal in the molecules even though technically SO2 should be a little shorter due to the double bond...
- Sun May 20, 2018 1:50 pm
- Forum: Dipole Moments
- Topic: Dipole moment as a vector [ENDORSED]
- Replies: 2
- Views: 196
Re: Dipole moment as a vector [ENDORSED]
The partial negative results from the electrons being pulled toward the more electronegative atom, which is why the arrow points toward the partial negative: that is the way the electrons are being pulled.
- Sun May 20, 2018 1:47 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Absent Friday
- Replies: 4
- Views: 510
Re: Absent Friday
We discussed the strength of the interactions Alejandro listed as well as what effect interaction strength has on properties of a compound.
- Wed May 16, 2018 3:14 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: In Class Example, Re: radicals, NO
- Replies: 2
- Views: 213
Re: In Class Example, Re: radicals, NO
Remember that O always has an octet because of its high electronegativity, and that should help.
- Wed May 16, 2018 3:12 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: formal charge
- Replies: 11
- Views: 761
Re: formal charge
Formal charge = number of lone pair electrons - 1/2 * number of bonding electrons
- Sat May 05, 2018 10:03 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Homework 2.55
- Replies: 2
- Views: 202
Re: Homework 2.55
Group 15 includes N, P, As, Sb, Bi. Each has a valence electron configuration of (n-1)d10 ns2 np3, the d group is not included because the electrons in the d subshell are in the shell n-1, so they aren't valence electrons. For example, arsenic has a configuration of [Ar] 3d10 4s2 4p3. Because the d ...
- Sat May 05, 2018 9:57 pm
- Forum: Trends in The Periodic Table
- Topic: 2.67 part c) and d) [ENDORSED]
- Replies: 5
- Views: 372
Re: 2.67 part c) and d) [ENDORSED]
Also, since chlorine and sodium have fewer electrons, there is less shielding, making the effective nuclear charge larger and making it harder to remove electrons.
- Sat May 05, 2018 9:23 pm
- Forum: Trends in The Periodic Table
- Topic: 2.67 part C (electron affinity)
- Replies: 3
- Views: 208
Re: 2.67 part C (electron affinity)
I was wondering this too, so I looked it up. Apparently, a half-filled p subshell is more stable than one with only 2 electrons, so this is why carbon has a higher electron affinity than nitrogen.
- Sun Apr 29, 2018 2:13 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Short hand? [ENDORSED]
- Replies: 1
- Views: 179
Re: Short hand? [ENDORSED]
Inert gases have a full outer energy shell, so using them is basically saying that the last energy shell is completely full, and then you add the rest of the configuration for whichever atom you are specifying. For example, if I was talking about carbon, I would say [He] 2s^2 2p^2 to say that n=1 is...
- Sun Apr 29, 2018 2:03 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Fourth Quantum Number
- Replies: 5
- Views: 348
Re: Fourth Quantum Number
I don't think you necessarily need to calculate whether the spin is up or down, you just need to know that if there are 2 electrons occupying the same orbital, one will spin up and one down.
- Sun Apr 29, 2018 1:59 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: h-bar [ENDORSED]
- Replies: 7
- Views: 557
Re: h-bar [ENDORSED]
The Uncertainty Equation stated in the textbook has 1/2 * h-bar, and since h-bar is h/2pi, we use h/4pi.
- Mon Apr 23, 2018 7:59 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation [ENDORSED]
- Replies: 3
- Views: 309
Re: Rydberg Equation [ENDORSED]
If we find it faster and easier to use the Rydberg equation on a test or quiz, are we allowed to use it as long as we understand the concepts?
- Sun Apr 22, 2018 12:06 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: The Negative Sign in En = -hR/n^2
- Replies: 5
- Views: 310
Re: The Negative Sign in En = -hR/n^2
So as a follow up, when using the Rydberg equation, the negative is there for the same reason? Is it because the Rydberg equation is derived from this equation? When calculating frequency from the Rydberg equation, we could just ignore the negative, correct?
- Sat Apr 21, 2018 9:11 pm
- Forum: Photoelectric Effect
- Topic: Significance of intensity [ENDORSED]
- Replies: 7
- Views: 418
Re: Significance of intensity [ENDORSED]
Continuing off that note, when light acts as a wave, or for any wave, the intensity relates to the amplitude/height of the wave.
- Sat Apr 21, 2018 9:09 pm
- Forum: Properties of Light
- Topic: units for frequency and wavelength [ENDORSED]
- Replies: 9
- Views: 431
Re: units for frequency and wavelength [ENDORSED]
I believe it's preferred for very small wavelengths such as ones in the visible region to be written in nanometers, but you won't get points off for writing it in meters.
- Sat Apr 21, 2018 9:05 pm
- Forum: Properties of Light
- Topic: HW #1.57 [ENDORSED]
- Replies: 1
- Views: 154
Re: HW #1.57 [ENDORSED]
The first wavelength (656.3) is the longest, meaning it has the lowest energy. This must mean it must result from the smallest energy level transition. Since the Balmer series is for visible light, it involves n=2. In this case, the fist stated wavelength is for the transition n1=2 to n2=3, the smal...
- Sun Apr 15, 2018 2:38 pm
- Forum: Properties of Light
- Topic: Value of speed of light [ENDORSED]
- Replies: 4
- Views: 311
Re: Value of speed of light [ENDORSED]
Use whichever constant is given on the test just to be safe.
- Sun Apr 15, 2018 2:38 pm
- Forum: Properties of Light
- Topic: Data to memorize for this chapter [ENDORSED]
- Replies: 2
- Views: 152
Re: Data to memorize for this chapter [ENDORSED]
Also, Dr Lavelle said all the equations would be on the test, but you should know how to use them. I'm sure he doesn't expect us to memorize the EM spectrum, as he gives all constants on the tests. Hope this helps!
- Fri Apr 13, 2018 5:05 pm
- Forum: Photoelectric Effect
- Topic: Post module quiz #25
- Replies: 6
- Views: 217
Post module quiz #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 I thought the answer would be c, but it said this was wrong. Can someone please explain?
- Sat Apr 07, 2018 7:54 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Review Worksheet [ENDORSED]
- Replies: 3
- Views: 234
Re: Review Worksheet [ENDORSED]
I also find it very helpful to use unit conversions aka dimensional analysis to solve problems like this. For example, you know 0.12*750mL will give you the volume in mL. Now you want to find the mass in grams, so you need the units to be g/mL in order for mL to cancel, and you'll be left with grams...
- Sat Apr 07, 2018 7:44 pm
- Forum: Balancing Chemical Reactions
- Topic: Common Compounds to know
- Replies: 3
- Views: 306
Re: Common Compounds to know
Dr Lavelle said after class that we wouldn't be expected to know this for the first test.
- Sat Apr 07, 2018 7:40 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing equations with fractions [ENDORSED]
- Replies: 13
- Views: 818
Re: Balancing equations with fractions [ENDORSED]
Definitely multiply the whole thing by 2. Dr Lavelle said in class that stoichiometric coefficients should be whole numbers.