Search found 54 matches
- Sat Dec 07, 2019 11:09 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Lavelle's Review - Heisenberg's
- Replies: 1
- Views: 341
Lavelle's Review - Heisenberg's
I did not quite understand the second question Lavelle went over in his review of past exam questions. What is the Heisenberg equation and how do we use it?
- Sat Dec 07, 2019 8:20 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Hw Problem 6D.11
- Replies: 4
- Views: 407
Hw Problem 6D.11
For 6D.11, I understand that the ions in the salt would indicate whether the pH will be less or more than 7 (or neutral). However, I used the charts in the textbook to see whether they are ions from strong/weak acids or bases. Do you memorize the different cations and anions for the final? Does anyo...
- Sat Dec 07, 2019 8:16 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: 6D.11 (e) & (f)
- Replies: 2
- Views: 332
Re: 6D.11 (e) & (f)
I don't know if this is extremely helpful but you can refer to Table 6D.1 in the textbook and it shows all the small, highly charged metal cations that are written with (H2O)6. This is how I know when and where to include it.
- Sat Dec 07, 2019 8:09 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Midterm 6A
- Replies: 1
- Views: 272
Midterm 6A
The question was: Magnesium ions are a known cofactor in over 300 enzymatic reactions. What are the possible angular momentum quantum numbers of the highest energy electrons in these magnesium ions? Indicate the corresponding subshell of each angular momentum quantum number. I understand that the hi...
- Sat Dec 07, 2019 4:59 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Ka, Kb, pKa, etc. on Final
- Replies: 2
- Views: 236
Ka, Kb, pKa, etc. on Final
Our TA mentioned that Ka and Kb won't be in the final, but we spent a considerable amount of time on it and it is in our outline. What do we really need to know about it besides its relationship to acidic/basic strengths?
- Sat Dec 07, 2019 4:03 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Relationship between pKa, pKb, and acidity strength?
- Replies: 1
- Views: 165
Relationship between pKa, pKb, and acidity strength?
I am confused about the concept of pKa, pKw, and pKb. What exactly are they and what is their relationship to each other? What type of calculations are involved?
- Sun Dec 01, 2019 6:32 pm
- Forum: Student Social/Study Group
- Topic: final
- Replies: 4
- Views: 334
Re: final
I believe the final is cumulative but the material we learned after the midterm will probably be heavily emphasized. I also heard that the final is more conceptual than the exams we've had so far.
- Sun Dec 01, 2019 6:29 pm
- Forum: Conjugate Acids & Bases
- Topic: Naming Coordinate Compounds
- Replies: 2
- Views: 230
Naming Coordinate Compounds
Is the best way to remember how to name coordinate compounds is to memorize all the rules? Does anyone have any tips?
- Sun Dec 01, 2019 6:11 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Test Grades
- Replies: 6
- Views: 441
Re: Test Grades
My grade for Test 2 is also a 0. The grades will probably be released Monday or Tuesday this coming week.
- Sun Dec 01, 2019 6:09 pm
- Forum: General Science Questions
- Topic: Final Review
- Replies: 3
- Views: 329
Re: Final Review
I believe so. Lavelle will most likely provide us a list of review sessions from TAs, UAs, and himself for the final.
- Sun Dec 01, 2019 6:07 pm
- Forum: Student Social/Study Group
- Topic: Study Strategies
- Replies: 6
- Views: 475
Study Strategies
I heard that the final is very conceptual. I used to do all the homework problems to study for the tests and midterm and I have done alright, not super well. What study strategies would be best for the final?
- Sun Nov 24, 2019 3:47 pm
- Forum: Naming
- Topic: Chemistry Community
- Replies: 4
- Views: 294
Re: Chemistry Community
For me, I usually don't have many questions to ask. I like to look at other students' questions and if I don't know how to answer them, I look for the answers. I find that this is the most productive way to learn. As a result, I get to learn something I don't know AND answer someone's posts as part ...
- Sun Nov 24, 2019 3:35 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma & Pi Bonds
- Replies: 9
- Views: 629
Re: Sigma & Pi Bonds
They are both covalent bonds formed by the overlap of atomic orbitals. Sigma bonds are formed by end-to-end overlaps and pi bonds are formed by side-to-side overlaps (the lobes of the orbitals overlapping one another). Sigma bonds are stronger because there is generally more overlap compared to pi b...
- Sun Nov 24, 2019 3:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 2
- Views: 279
Re: Bond Angles
I attached a picture of a molecular geometry chart. It includes the names, the bond angles, and pictures. You can also google "molecular geometry chart" and see many examples that include bond angles, pictures of the shapes, and the corresponding names.
- Sun Nov 24, 2019 3:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Attach Pictures
- Replies: 3
- Views: 383
Attach Pictures
How do we attach pictures in our posts for chemistry community? I see the Img option on the top of the text box but how does it work?
- Sun Nov 24, 2019 3:14 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Lewis Acids
- Replies: 4
- Views: 273
Re: Lewis Acids
Lewis acids accept an electron pair and will have vacant orbitals. I think this goes for all common “acids” if that is what you mean by “regular.”
- Sun Nov 24, 2019 3:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Shape
- Replies: 31
- Views: 2988
Re: Bent Shape
It can have one lone pair or two lone pairs. This is a link to an image showing the two different molecular shapes: http://intro.chem.okstate.edu/1314F97/C ... PMain.html
- Thu Nov 14, 2019 11:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: "Less than" Degrees (HW)
- Replies: 1
- Views: 187
"Less than" Degrees (HW)
On homework questions, 2E.5, 2E.7, and 2E.9, the answers to the bond angles are all "less than blank." Is this because they all have lone pairs that push the bonded pairs together creating a "less than" degree. Why is that? Does this "less than" degree occur between onl...
- Thu Nov 14, 2019 11:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Textbook question 2E.1
- Replies: 4
- Views: 274
Re: Textbook question 2E.1
Since bond angles are affected by the presence of lone pairs of electrons at the central atom, we can tell if there are lone pairs when a picture only shows bonded pairs/atoms. A lone pair of electrons at the central atom would always repel the shared pair/bonded pair which is why the 120-degree ang...
- Thu Nov 14, 2019 11:19 pm
- Forum: Bond Lengths & Energies
- Topic: Explain what ion-ion, ion-dipole, etc.
- Replies: 2
- Views: 357
Re: Explain what ion-ion, ion-dipole, etc.
Ion-ion interactions are an attractive force between ions with opposite charges. An ion-dipole interaction is the result of an electrostatic interaction between a charged ion and a neutral molecule that has a dipole (temporarily charged dipole). For example, a positive ion (cation) attracting the pa...
- Thu Nov 14, 2019 11:03 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lewis Structures & VSEPR
- Replies: 9
- Views: 490
Re: Lewis Structures & VSEPR
The Lewis Structure can help you visualize the bonded pairs and the lone pairs so I personally believe it is very helpful to draw it out while using the VSEPR model. I think once you are familiar with the shape of a molecule, you wouldn't need to draw out the Lewis Structure.
- Thu Nov 14, 2019 10:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T-shaped vs Trigonal Bipyramidal
- Replies: 2
- Views: 244
T-shaped vs Trigonal Bipyramidal
On homework problem 2E.9, ICL3 is T-shaped but what is the difference between trigonal bipyramidal and T-shaped?
- Thu Nov 14, 2019 10:34 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E1 - Molecules with bent geometry
- Replies: 7
- Views: 420
Re: 2E1 - Molecules with bent geometry
I think a good example would be XeF2 where it has 2 bound atoms and 3 lone pairs. Another example would be I3.
- Sat Nov 09, 2019 5:57 pm
- Forum: Lewis Structures
- Topic: Lewis Structures
- Replies: 4
- Views: 366
Re: Lewis Structures
You would have to find out the formal charge of both atoms. I usually do this by comparing the number of electrons that are surrounding an atom with the number of electrons the neutral atom normally has. However, the atom with greater electronegativity usually has a negative charge or at least that ...
- Sat Nov 09, 2019 5:53 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Hydrogen Bonding
- Replies: 4
- Views: 259
Re: Hydrogen Bonding
The electronegative atom must have one or more unshared electron pairs (which oxygen and nitrogen have). The atoms must also have a partial negative charge. The hydrogen (has a partial positive charge) is attracted to the partial negative charge of oxygen or nitrogen which has excess electrons to sh...
- Sat Nov 09, 2019 5:46 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Dipole-Dipole vs London
- Replies: 4
- Views: 322
Re: Dipole-Dipole vs London
Dipole-dipole interactions occur when the positively charged part of a molecule interacts with the negatively charged part of another molecule. Induced dipole-induced dipole or London dispersion forces exist between all types of molecules (polar or nonpolar). Electrons constantly move so an atom or ...
- Sat Nov 09, 2019 5:43 pm
- Forum: Dipole Moments
- Topic: Dipole-Dipole Interactions / H-bonding
- Replies: 2
- Views: 184
Dipole-Dipole Interactions / H-bonding
So to clarify, hydrogen bonding is a type of dipole-dipole interaction, but it is only between hydrogen and oxygen, nitrogen, or fluorine atom. While dipole-dipole is the strongest interaction between atoms and molecules, hydrogen bonding is the strongest which makes it THE strongest interaction?
- Sat Nov 09, 2019 5:38 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Dipole-dipole v. Induced Dipole-Induced Dipole
- Replies: 2
- Views: 158
Re: Dipole-dipole v. Induced Dipole-Induced Dipole
Dipole-dipole interactions occur when the positively charged part of a molecule interacts with the negatively charged part of another molecule. Induced dipole-induced dipole exists between all types of molecules (polar or nonpolar). Electrons constantly move so an atom or molecule can develop a temp...
- Fri Nov 01, 2019 10:51 am
- Forum: Octet Exceptions
- Topic: More than 8 valence e-
- Replies: 8
- Views: 419
Re: More than 8 valence e-
They are examples of expanded octets (expanded its valence shell). For phosphorus, there is the 3d subshell available and the d-orbitals that can accommodate for more valence electrons. This allows for extra pair of electrons to occupy the valence shell which means there are more than 8 valence elec...
- Fri Nov 01, 2019 10:40 am
- Forum: Student Social/Study Group
- Topic: Midterm question
- Replies: 3
- Views: 151
Re: Midterm question
Most likely, there will be one question (with multiple parts) on fundamentals out of 8 since we already had a test on it. The other questions would probably be split equally between the other topics.
- Fri Nov 01, 2019 10:38 am
- Forum: Electronegativity
- Topic: Electronegativity on Test
- Replies: 7
- Views: 262
Electronegativity on Test
Do we need to know how to calculate the exact number for electronegativity for the midterm and all the tests afterward? If not, is there anything else to know about electronegativity besides the general trends and information?
- Fri Nov 01, 2019 10:33 am
- Forum: Lewis Structures
- Topic: Best way to go about drawing Lewis structures
- Replies: 7
- Views: 347
Re: Best way to go about drawing Lewis structures
Your way is the process that I use when I draw Lewis structures. I also think as you draw more and more, you get used to it and begin to remember how certain structures look like. The two tips commented under this post are also very helpful.
- Fri Nov 01, 2019 10:26 am
- Forum: Administrative Questions and Class Announcements
- Topic: Bruincast
- Replies: 4
- Views: 285
Re: Bruincast
I believe the classes are not Bruincasted, but the video modules on the chem 14A website seem to be past lectures. However, the video modules only cover certain subjects and not all.
- Sun Oct 27, 2019 6:34 pm
- Forum: Sigma & Pi Bonds
- Topic: Single vs. Double bonds
- Replies: 15
- Views: 1956
Re: Single vs. Double bonds
In double bonds, there are four bonding electrons between two atoms instead of two in single bonds so there is more attraction between the atoms when there is a double bond. Stronger Attraction = Shorter Bond
- Sun Oct 27, 2019 6:11 pm
- Forum: Trends in The Periodic Table
- Topic: Electron affinity.
- Replies: 8
- Views: 287
Re: Electron affinity.
Electron affinity reflects the ability of an atom to accept an electron. When an electron is added to a gaseous atom, an energy change occurs which is the electron affinity. Atoms with greater effective nuclear charge have greater electron affinity.
- Sun Oct 27, 2019 6:01 pm
- Forum: Trends in The Periodic Table
- Topic: Central Atom
- Replies: 13
- Views: 543
Re: Central Atom
The atom with the lowest ionization energy is usually the central atom because it is able to create the most bonds. You can also look for the atom with the lowest electron affinity since they share the same trend.
- Sun Oct 27, 2019 5:56 pm
- Forum: Ionic & Covalent Bonds
- Topic: Resonance
- Replies: 10
- Views: 423
Re: Resonance
The Lewis structure is a simplification for the structure of the molecule but it is helpful to visualize it. The bonds can be written in as many ways as the bonds can be arranged which indicates resonance. The actual molecule is an average of the resonance structures.
- Sun Oct 27, 2019 5:52 pm
- Forum: Lewis Structures
- Topic: Lone pair
- Replies: 8
- Views: 404
Re: Lone pair
Lone pairs are valence electrons that are not shared with another atom in a bond. They are found in the outermost electron shell of atoms.
- Sun Oct 20, 2019 1:12 pm
- Forum: Properties of Light
- Topic: Baler v. Lyman Series
- Replies: 10
- Views: 535
Re: Baler v. Lyman Series
The Balmer series corresponds to the region of visible light on the spectrum and the electrons drop to n=2. The Lyman series corresponds to the region of ultraviolet light and electrons drop to n=1.
- Sun Oct 20, 2019 1:02 pm
- Forum: Photoelectric Effect
- Topic: When energy is equal to work function
- Replies: 9
- Views: 997
Re: When energy is equal to work function
If the energy of the photon is equal to that of the work function, it means that the energy threshold will be met and the electron will be ejected.
- Sun Oct 20, 2019 12:39 pm
- Forum: Administrative Questions and Class Announcements
- Topic: UA Session and Step-Up Program
- Replies: 4
- Views: 260
Re: UA Session and Step-Up Program
The step-up sessions consist of the UA going over topics and problems that were covered in past lectures. Usually, at the end of the session, the UA is open to any questions pertaining to the course. You can drop into any session and there’s no need to register and you can leave any time.
- Sat Oct 19, 2019 6:31 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Tips for the Midterm
- Replies: 10
- Views: 369
Re: Tips for the Midterm
My TA told us that the best study method would be to do all the homework problems that are assigned and really try to understand the concept behind them. For me, I also like to review my notes, watch the video modules, and go through the checklist on the outlines to make sure I understand everything...
- Thu Oct 17, 2019 11:40 pm
- Forum: Photoelectric Effect
- Topic: Confusion on equations
- Replies: 9
- Views: 378
Re: Confusion on equations
It all depends on what you are looking for and what the problem gives you. Like others have said, the formulas can be rewritten or combined to yield the correct results.
- Sat Oct 12, 2019 1:37 am
- Forum: Properties of Electrons
- Topic: Electron After Excited State
- Replies: 7
- Views: 431
Electron After Excited State
After an electron reaches an excited state, does it fall down to its original energy level because it cannot maintain it? What are the results?
- Sat Oct 12, 2019 1:28 am
- Forum: Properties of Light
- Topic: Shorter Wavelength
- Replies: 3
- Views: 187
Shorter Wavelength
Photons with shorter wavelengths have greater energy (higher frequency). Is this why they eject electrons more than photons with longer wavelengths? If it is, why is that so?
- Sat Oct 12, 2019 1:09 am
- Forum: Einstein Equation
- Topic: Planck's Constant
- Replies: 3
- Views: 304
Planck's Constant
The energy of light is related to its frequency, but what is the relationship between Planck's Constant to frequency and energy? How does it affect the two?
- Sat Oct 12, 2019 1:02 am
- Forum: Properties of Light
- Topic: Color of Light
- Replies: 2
- Views: 202
Color of Light
The color of light is determined by its wavelength. Is this what establishes the relationship between the color of light and the energy level electrons jumps from and to?
- Sat Oct 12, 2019 12:36 am
- Forum: Properties of Electrons
- Topic: Wave-Particle Duality
- Replies: 1
- Views: 153
Wave-Particle Duality
Can someone explain more in-depth what wave-particle duality is and how light can be both?
- Thu Oct 03, 2019 10:27 pm
- Forum: SI Units, Unit Conversions
- Topic: which unit to use
- Replies: 9
- Views: 524
Re: which unit to use
I think if the problem gives you the same unit throughout, you can keep it as is, but I don't think it'll hurt to convert it to base units. I usually use the most “standard” one or SI base units if there are more than two units involved with the problem so mol instead of mmol or meter instead of mil...
- Thu Oct 03, 2019 10:20 pm
- Forum: Limiting Reactant Calculations
- Topic: Basic Question
- Replies: 11
- Views: 570
Re: Basic Question
It would be very unlikely for there to be two limiting reactants because they would have to be of the same amount.
- Thu Oct 03, 2019 9:55 pm
- Forum: Empirical & Molecular Formulas
- Topic: 100 Gram Procedure
- Replies: 4
- Views: 195
100 Gram Procedure
Why is it easier to imagine the sample mass as 100 grams when calculating the empirical formula? Also, I just want to confirm that it will only work if we calculated the mass percentage already? And this will work as long as we calculate the mass percentages from the original mass given in the probl...
- Thu Oct 03, 2019 9:45 pm
- Forum: Limiting Reactant Calculations
- Topic: Clarification
- Replies: 4
- Views: 387
Re: Clarification
Exactly what you said, the limiting reagent or limiting reactant determines how much of the products are made because if a reaction runs out of any reactant, the amount of product is limited as a result. And the theoretical yield is the maximum amount of product that can be produced calculated with ...
- Thu Oct 03, 2019 7:09 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Volume formulas
- Replies: 6
- Views: 218
Re: Volume formulas
The first is usually used to find the molarity of a solution when the moles of solute (n) and the volume of solution (v) are given. The formula can also be rearranged to find moles or volume if the other two values are given. The second formula is used when dilution is occurring (adding more solvent...
- Thu Oct 03, 2019 6:30 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Fundamentals G5
- Replies: 3
- Views: 153
Re: Fundamentals G5
First, you have to find the molarity of the sodium carbonate which is 0.08mol/L. For a), I converted mmol to moles (1 mmol = .001 mol). Since there are 2 Na’s in sodium carbonate, the molarity will be twice that of the solution which means 0.08 x 2 (the molarity will be 0.16mol/L). Then it will be (...