Search found 30 matches
- Sat Dec 01, 2018 12:22 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 514033
Re: Saying Thank You to Dr. Lavelle
Thank you Dr. Lavelle for making your lectures informative and engaging. It has been easy to keep up with the material presented and I am looking forward to 14B next quarter.
- Sat Dec 01, 2018 12:14 pm
- Forum: Sigma & Pi Bonds
- Topic: Number of Sigma and Pi Bonds
- Replies: 6
- Views: 983
Re: Number of Sigma and Pi Bonds
pi bonds form between p orbitals -- there are 3 of them per atom
- Sat Dec 01, 2018 12:06 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Equilibrium Constants
- Replies: 2
- Views: 308
Re: Equilibrium Constants
Strong acids/base reactions go so far towards dissociation we assume they completely dissociate, so no equilibrium constant needs to be solved for. (There are basically no reactants left)
- Tue Nov 27, 2018 10:31 am
- Forum: Hybridization
- Topic: Pi bonds
- Replies: 3
- Views: 331
Re: Pi bonds
Pi bonds bond above and below the molecule and lock the molecule in place, preventing rotation unlike sigma bonds who bond at one point in the center
- Tue Nov 27, 2018 9:57 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Double Bonds as Regions of Electron Density
- Replies: 5
- Views: 432
Re: Double Bonds as Regions of Electron Density
Single, Double, Triple bonds all counts as one region of electron density.
- Tue Nov 27, 2018 9:56 am
- Forum: Hybridization
- Topic: Just Kind of Confused
- Replies: 13
- Views: 989
Re: Just Kind of Confused
I think it's just more of a stylistic thing and personal preference.
- Tue Nov 27, 2018 9:46 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw or Square Planar
- Replies: 3
- Views: 2183
Re: Seesaw or Square Planar
AX4E is Seesaw (dsp3), AX4E2 is Square Planar (d2sp3)
- Tue Nov 27, 2018 9:45 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: test #3
- Replies: 14
- Views: 1459
Re: test #3
Dimagnetic elements have no unpaired electrons, while paramagnetic elements have at least 1.
- Tue Nov 27, 2018 9:39 am
- Forum: Hybridization
- Topic: s-character
- Replies: 6
- Views: 2589
Re: s-character
sp: 1/2
sp2: 1/3
sp3: 1/4
dsp3: 1/5
d2sp3: 1/6
It's the ratio of the orbitals.
sp2: 1/3
sp3: 1/4
dsp3: 1/5
d2sp3: 1/6
It's the ratio of the orbitals.
- Sun Nov 18, 2018 11:42 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles for H2O
- Replies: 8
- Views: 8868
Re: Bond Angles for H2O
Lone pairs take up more space than bonding pairs, so instead of 109.5 for tetrahedral you get 104.5 and bent.
- Sun Nov 18, 2018 11:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: lone pair influence on shape
- Replies: 12
- Views: 4220
Re: lone pair influence on shape
Lone pairs take up more space than bonding pairs, depressing the bond angle.
- Sun Nov 18, 2018 11:18 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 16
- Views: 1161
Re: Bond Angles
It would probably be safe to know the most common ones just in case they come up on a test.
- Sun Nov 11, 2018 3:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar and Nonpolar Molecules
- Replies: 4
- Views: 459
Re: Polar and Nonpolar Molecules
The water molecules are more attracted to one another (dipoles) than to the oil molecules. The oil molecules are said to be hydrophobic and do not mix with water for this reason.
- Sun Nov 11, 2018 3:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs on Neighboring Atoms
- Replies: 2
- Views: 254
Re: Lone Pairs on Neighboring Atoms
Lone pairs on neighboring atoms would repel one another because they are all negative (only electrons form lone pairs). This weakens the bond in question.
- Sun Nov 11, 2018 12:45 pm
- Forum: Bond Lengths & Energies
- Topic: VSEPR Model for Water
- Replies: 3
- Views: 376
Re: VSEPR Model for Water
The oxygen molecule on water has 2 lone pairs that cause the bond angle to be slightly depressed to around 109.5; this is called a bent configuration.
- Sun Nov 04, 2018 10:17 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge and Lewis Structures
- Replies: 5
- Views: 617
Re: Formal Charge and Lewis Structures
Generally the most stable configuration is one where the formal charge is minimized on all the atoms involved. Usually you don't have to draw them but it can be helpful if a test question were to ask of the two lewis structures which one is favored.
- Sun Nov 04, 2018 10:11 pm
- Forum: Sigma & Pi Bonds
- Topic: Midterm1
- Replies: 10
- Views: 1114
Re: Midterm1
It shows up on a lot of old midterms but I'm guessing they had already gotten to hybridization by that point. I don't think it would show up on tomorrow's midterm (that would be a really unfair question)
- Sun Nov 04, 2018 10:09 pm
- Forum: Ionic & Covalent Bonds
- Topic: Chem Midterm
- Replies: 13
- Views: 1093
Re: Chem Midterm
Do you guys know how many points total you can get taken off of the midterm if you miss sig figs and units, but get all of the math/concepts right? Looking at previous midterms, you usually lose 1 or 2 points per problem for sig figs or units if you mess either up. So for a question say Q4A, Q4B, a...
- Tue Oct 23, 2018 2:03 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Exercise 2.29
- Replies: 10
- Views: 3555
Re: Exercise 2.29
For Problem 2.49 "Predict the number of valence electrons present in each of the following atoms (include the outermost d-electrons: (a) N; (b) Ag; (c) Nb; (d) W." What trend are we expected to see in order to identify the number of valence electrons? The atomic number? Is there also some...
- Tue Oct 23, 2018 2:00 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Exercise 2.29
- Replies: 10
- Views: 3555
Re: Exercise 2.29
In 2.29 part c), I don't understand why the maximum number of electrons is 8 if n=2. Can someone please explain? At energy level 2, there are two possible subshells: s and p. (Remember that 2d and 2f do not exist). The s subshell can hold 2 electrons, while the 3 p orbitals combined hold 6 electron...
- Tue Oct 23, 2018 1:59 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Exercise 2.29
- Replies: 10
- Views: 3555
Re: Exercise 2.29
For Exercise 2.29 (Chapter 2 The Quantum Mechanics in Action: Atoms) How many electrons can have the following quantum numbers in an atom: a) n = 2, l = 1 b) n = 4, l = 2, ml = -2 c) n = 2 d) n = 3, l = 2, ml = +1 Does anyone know how to solve this problem? Thank you in advance The question varies i...
- Sat Oct 20, 2018 2:43 pm
- Forum: DeBroglie Equation
- Topic: Wave properties of large particles
- Replies: 3
- Views: 352
Re: Wave properties of large particles
The wave properties do exist for relatively large objects, but those wavelengths are so small we do not have equipment that can detect waves in the 10^-35 spectrum.
- Sat Oct 20, 2018 2:41 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: ml Quantum Number
- Replies: 4
- Views: 688
Re: ml Quantum Number
ml is used to describe the individual orbital within a subshell.
For l = 0 (s orbital), then the only ml possible is 0 (there is only one s orbital).
For l = 1 (p orbital), you can have ml = -1 (px), 0 (py), or 1 (pz), and so forth for other orbitals.
For l = 0 (s orbital), then the only ml possible is 0 (there is only one s orbital).
For l = 1 (p orbital), you can have ml = -1 (px), 0 (py), or 1 (pz), and so forth for other orbitals.
- Sat Oct 20, 2018 2:39 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shielding [ENDORSED]
- Replies: 15
- Views: 2044
Re: Shielding [ENDORSED]
The p-orbital experiences less pull from the nucleus because some of the repulsion from s-orbital electrons are also affecting it. Thus, we need something called effective nuclear charge to describe the binding strength of electrons. They are the same energy level (in the case of 2s and 2p) but are ...
- Sat Oct 13, 2018 8:54 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: diatomic elements
- Replies: 12
- Views: 9710
Re: diatomic elements
Diatomics exist to share electrons covalently and achieve a lower energy state.
HOFBrINCl is a metonym to remember the diatomics:
H- Hydrogen
O- Oxygen
F- Fluorine
Br- Bromine
I- Iodine
N- Nitrogen
Cl- Chlorine
HOFBrINCl is a metonym to remember the diatomics:
H- Hydrogen
O- Oxygen
F- Fluorine
Br- Bromine
I- Iodine
N- Nitrogen
Cl- Chlorine
- Sat Oct 13, 2018 8:52 pm
- Forum: Trends in The Periodic Table
- Topic: electron affinity [ENDORSED]
- Replies: 15
- Views: 1933
Re: electron affinity [ENDORSED]
Atoms with low electron affinity (i.e. alkali metals) lose electrons far more easily to have a full valence shell whereas it is far easier for a halogen (say Fluorine) to pick up an electron and fill its valence shell. Thus, we say halogens have a high electron affinity.
- Mon Oct 08, 2018 4:27 pm
- Forum: Properties of Light
- Topic: Quanta & Photons
- Replies: 5
- Views: 389
Re: Quanta & Photons
In essence, you can never have light that strikes in 1.2 photons, 5.64 photons, etc. The particle nature of light only travels in whole number of "packets".
- Sun Sep 30, 2018 4:21 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Question E16 - Transition Metal Charge
- Replies: 4
- Views: 373
Re: Question E16 - Transition Metal Charge
Silver generally is found in the +1 oxidation state.
Other ones of note are Iron being +2 or +3, copper being +1, etc.
Other ones of note are Iron being +2 or +3, copper being +1, etc.
- Sun Sep 30, 2018 12:18 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Study Module Post-assessment Question
- Replies: 5
- Views: 340
Re: Study Module Post-assessment Question
MinitialVinitial = MfinalVfinak
Minitial = 0.2109 M
Vinitial = 0.02 L (Only 20.0 mL is transferred)
Vfinal = 0.250 L
Solve for Mfinal, which should be 1.69 x 10-2 M
Minitial = 0.2109 M
Vinitial = 0.02 L (Only 20.0 mL is transferred)
Vfinal = 0.250 L
Solve for Mfinal, which should be 1.69 x 10-2 M
- Sun Sep 30, 2018 12:09 pm
- Forum: Empirical & Molecular Formulas
- Topic: Mutiplying by a number
- Replies: 3
- Views: 244
Re: Mutiplying by a number
If it looks like or is close to a fraction, multiply by its inverse to clear a fraction
(e.g. x.3333 multiply by 3, x.25 multiply by 4, x.2 multiply by 5, x.5 multiply by 2, x.75 multiply by 4/3)
If its close to a whole number, just round up (x.9545 just round to the next number)
(e.g. x.3333 multiply by 3, x.25 multiply by 4, x.2 multiply by 5, x.5 multiply by 2, x.75 multiply by 4/3)
If its close to a whole number, just round up (x.9545 just round to the next number)