Search found 50 matches
- Sat Dec 07, 2019 1:15 pm
- Forum: Conjugate Acids & Bases
- Topic: Ammonia and Ammonium
- Replies: 2
- Views: 350
Re: Ammonia and Ammonium
I think the strength of a conjugate acid/base is relative to the acid/base that it is a conjugate for. So, while the conjugate acid of a weak base is strongER, it doesn't necessarily have to fall under the classification of a strong acid.
- Sat Dec 07, 2019 1:13 pm
- Forum: *Shrodinger Equation
- Topic: schrodingers equation
- Replies: 8
- Views: 620
Re: schrodingers equation
I remember Dr. Lavelle saying during one of the lectures that we won't need to use the equation for any calculations, but it's probably good to know what it is used for and its conceptual basis just in case.
- Wed Dec 04, 2019 8:47 am
- Forum: Biological Examples
- Topic: Coordination Compounds and Chemotherapy Drugs
- Replies: 5
- Views: 349
Re: Coordination Compounds and Chemotherapy Drugs
Does anyone know what information we have to specifically know about these chemotherapy drugs? Is it just that they're an example of a coordination compound? I was absent during this lecture, so I'd appreciate any information! Thank you so much :) I think the main thing we need to know about cispla...
- Wed Dec 04, 2019 8:44 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: week 9 hw problems
- Replies: 4
- Views: 264
Re: week 9 hw problems
theoretically, you can do any 5 questions from either section, but I think what most people did was 5 questions from coordination compounds for week 9 and 5 questions from acids and bases for week 10.
- Wed Dec 04, 2019 8:32 am
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Community Posts
- Replies: 10
- Views: 585
Re: Chemistry Community Posts
I'm not sure, but for me, my homework grades on MyUCLA are updated and my chemistry community points aren't, so I'm assuming it's at the end of the quarter.
- Wed Dec 04, 2019 8:31 am
- Forum: Identifying Acidic & Basic Salts
- Topic: 6D11
- Replies: 2
- Views: 237
Re: 6D11
Like the previous comment said, I don't think the question is asking for the exact pH, but rather, for the relative pH. Meaning, it is asking to analyze whether the salt acts as an acid or a base (or neither), and how it interacts with water/whether or not it produces H3O+ ions.
- Wed Dec 04, 2019 8:28 am
- Forum: Bronsted Acids & Bases
- Topic: CaO
- Replies: 10
- Views: 1470
Re: CaO
CaO is a strong base because it fully dissociates into its constituent components
- Wed Dec 04, 2019 8:26 am
- Forum: Bronsted Acids & Bases
- Topic: How to determine whether a molecule is an acid or a base
- Replies: 5
- Views: 297
Re: How to determine whether a molecule is an acid or a base
A base is a molecule that donates electrons, meaning the molecule will usually have one or more lone electron pairs. In this case, the N in NH3 has a lone electron pair, so it is a base.
- Wed Dec 04, 2019 8:24 am
- Forum: Bronsted Acids & Bases
- Topic: Strong Acids and Bases
- Replies: 4
- Views: 372
Re: Strong Acids and Bases
We don't have to memorize all of them, however, I agree that it would be to your benefit to know the most common ones, either the ones given on the table in section 6C.3 in the book, or by just seeing which ones most commonly come up in practice problems.
- Wed Dec 04, 2019 8:22 am
- Forum: Lewis Acids & Bases
- Topic: Strong Acids
- Replies: 6
- Views: 364
Re: Strong Acids
A strong acid is one that dissociates into its constituent parts (cation and anion) when dissolved in water
- Sun Nov 24, 2019 10:57 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligand
- Replies: 10
- Views: 465
Re: Ligand
A ligand is an ion or molecule that bonds to the central metal atom of a coordination compound by donating a pair of electrons to it, meaning that it must have one or more lone pairs of electrons.
- Sun Nov 24, 2019 10:55 pm
- Forum: Biological Examples
- Topic: Cisplatin [ENDORSED]
- Replies: 19
- Views: 1200
Re: Cisplatin [ENDORSED]
Cisplatin can stop the division of cancer cells, however, it doesn't target cancer cells specifically, so it can potentially stop the division of normal, healthy cells.
- Sun Nov 24, 2019 8:56 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: What are coordination numbers?
- Replies: 3
- Views: 303
Re: What are coordination numbers?
The coordination number represents the amount of bonded sites a central metal atom of a coordination compound has
Re: Class
Technically, the deadline to switch it was the end of week 7, but I don't think it would hurt to talk to Lavelle about it and see if there's a way around it
- Sun Nov 24, 2019 4:53 pm
- Forum: Naming
- Topic: coordination compounds
- Replies: 4
- Views: 217
Re: coordination compounds
I think either one is fine, since we were taught both
- Sat Nov 16, 2019 3:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing Molecular Structures
- Replies: 8
- Views: 485
Re: Drawing Molecular Structures
The lines represent bonds that are to the side or up/down, the shaded triangle symbolizes a bond that is going forward (towards you), and the dashes represent bonds that are going backwards (away from you). However, for the purpose of this class, we don't need to draw them that specifically, we can ...
- Sat Nov 16, 2019 3:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: How to study for VSEPR?
- Replies: 9
- Views: 649
Re: How to study for VSEPR?
I agree that 2.E has a lot of great practice problems, but I am also checking out some worksheets on google and making notecards for each specific molecular geometry that includes: - shape/name - number of electron regions - number of bonded & lone electron pairs - bond angles - VSEPR notation (...
- Sat Nov 16, 2019 3:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shape of ClO2+
- Replies: 6
- Views: 429
Re: Shape of ClO2+
Trigonal planar would be the general arrangement of the structure, because the central atom has 3 electron regions, however, since only 2/3 of those electron regions are bonded and there is one lone pair, the molecular geometry is a bent shape.
- Sat Nov 16, 2019 3:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining VSEPR Model
- Replies: 3
- Views: 272
Re: Determining VSEPR Model
Theoretically yes, however I think when determining VSEPR model, it is assumed that the formal charge of the lewis structure at hand is already 0, or as close to 0 as it can be.
- Sat Nov 16, 2019 3:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 3
- Views: 213
Re: Bond Angles
I think we need to know the general bond angles and where they are located, however, for example in a bent structure, where the bond angle is <120, we only have to know that it is <120, not the exact angle for each specific structure.
- Sun Nov 10, 2019 12:46 am
- Forum: Bond Lengths & Energies
- Topic: Bond Lengths
- Replies: 8
- Views: 527
Re: Bond Lengths
Double bonds have a stronger attraction because there are more electrons involved in bonding, therefore they are shorter, and triple bonds involve even more electrons and have an ever greater attraction, and are therefore even shorter
- Sun Nov 10, 2019 12:40 am
- Forum: Bond Lengths & Energies
- Topic: Test 2 Topics
- Replies: 40
- Views: 1989
Re: Test 2 Topics
Test 2 is during week 8 (11/18-11/22) and only covers material from after the midterm
- Sun Nov 10, 2019 12:31 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: How to know where a double bond should go?
- Replies: 10
- Views: 1072
Re: How to know where a double bond should go?
It depends on the electron affinity of the atoms and how many electrons they need to complete their octet. in this case, for example, Cl already has 7 electrons and only needs one more to complete its octet, so adding a double and would violate the octet rule
- Sun Nov 10, 2019 12:20 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge Equation?
- Replies: 12
- Views: 490
Re: Formal Charge Equation?
Victoria Otuya 4F wrote:I learned an easier way to remember the formal charge equation: valence electron -(dots + line).
does this count "dots" as pairs of dots or individual ones?
- Sun Nov 10, 2019 12:17 am
- Forum: Lewis Structures
- Topic: Lewis structures that are not symmetrical
- Replies: 4
- Views: 543
Re: Lewis structures that are not symmetrical
I could be fully wrong here so if I am please someone else correct me: I believe that polarity has to do with the distribution/sharing of electrons, so regardless of which way the structure is "turned" when drawn, if the electrons are distributed equally then it is non polar, and if they a...
- Sun Nov 10, 2019 12:10 am
- Forum: Bond Lengths & Energies
- Topic: Strongest Bond
- Replies: 15
- Views: 7062
Re: Strongest Bond
Weakest to strongest in terms of interaction type:
LDF/Van der Waals, dipole-dipole, hydrogen, ionic, covalent
Weakest to strongest in terms of bond type:
single, double, triple
LDF/Van der Waals, dipole-dipole, hydrogen, ionic, covalent
Weakest to strongest in terms of bond type:
single, double, triple
- Sun Nov 10, 2019 12:08 am
- Forum: Resonance Structures
- Topic: Resonance Structure for 2B.15
- Replies: 3
- Views: 166
Re: Resonance Structure for 2B.15
No, the correct lewis structure would be '
Cl
|
N=O
|
O
with 2 lone pairs on the double bonded oxygen and 3 lone pairs on the single bonded oxygen, so the N doesn't violate the octet rule
Cl
|
N=O
|
O
with 2 lone pairs on the double bonded oxygen and 3 lone pairs on the single bonded oxygen, so the N doesn't violate the octet rule
- Sun Nov 10, 2019 12:03 am
- Forum: Sigma & Pi Bonds
- Topic: Single vs. Double bonds
- Replies: 15
- Views: 1830
Re: Single vs. Double bonds
Single bonds are a lot weaker than double bonds because there are less electrons involved in the bonding process. Since they are weaker, they aren't pulled as closely together, whereas double bonds are stronger and pulled closer to each other, and triple bonds even stronger and closer than that
- Sun Nov 10, 2019 12:01 am
- Forum: Dipole Moments
- Topic: Hydrogen Bonds
- Replies: 6
- Views: 304
Re: Hydrogen Bonds
Hydrogen bonds are the strongest types of bonds because they occur between Hydrogen and the most electronegative elements
- Sat Nov 09, 2019 11:59 pm
- Forum: Dipole Moments
- Topic: Van Der Waals
- Replies: 5
- Views: 199
Re: Van Der Waals
Van Der Waals forces, or London dispersion forces (LDFs), are the weakest form of interactions and are always present in every bond, because all bonds require at least some sort of attraction between atoms/molecules
- Sun Oct 27, 2019 4:11 pm
- Forum: Octet Exceptions
- Topic: expanded valence shells
- Replies: 4
- Views: 146
Re: expanded valence shells
Atoms in period 3 (or higher) have d-orbitals in their valence shells that can accommodate additional electrons after the typical limit of 8 valence e- is achieved.
- Sun Oct 27, 2019 4:08 pm
- Forum: Electronegativity
- Topic: Exceptions
- Replies: 7
- Views: 1035
Re: Exceptions
As a previous concept mentioned, electronegativity trends do not include noble gases. Aside from that, the 4 most electronegative elements (in order) are Fluorine, Oxygen, Nitrogen, and Chlorine; I think these are the only ones that are important to memorize outside of the regular periodic trends.
- Sun Oct 27, 2019 4:05 pm
- Forum: Bond Lengths & Energies
- Topic: Bond length strength
- Replies: 6
- Views: 272
Re: Bond length strength
The more bonds you have between two atoms, the shorter and stronger your bonds will be. So triple bonds are the shortest and strongest, and single bonds are the longest and weakest. Exact length to be used in calculations will most likely be given in the problem.
- Sun Oct 27, 2019 4:03 pm
- Forum: Lewis Structures
- Topic: Dots vs Lines in Lewis Structures
- Replies: 6
- Views: 384
Dots vs Lines in Lewis Structures
Does it matter whether we use dots or lines to represent the bonds in Lewis structures?
- Sun Oct 27, 2019 4:02 pm
- Forum: Resonance Structures
- Topic: Resonance Structures
- Replies: 5
- Views: 207
Resonance Structures
In lecture, we covered resonance structures and discussed how, if a molecule has multiple resonance structures, the one with formal charges closest to 0 is the most stable. Does that also make it the most accurate structure and therefore the correct answer? In other words, should we just draw out th...
- Sun Oct 20, 2019 11:49 am
- Forum: Properties of Light
- Topic: Question 1A.15
- Replies: 5
- Views: 217
Re: Question 1A.15
I had a hard time with this question too, I think we're supposed to use the Rydberg equation, but when I looked at the solutions guide I didn't fully understand it either, so other than that I don't know much, sorry!
- Sun Oct 20, 2019 11:47 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing Electron Configurations
- Replies: 3
- Views: 97
Re: Writing Electron Configurations
So as mentioned in the previous comments, those are noble gases that are unreactive and have full valence electron shells. Essentially, think of it as substituting a variable for the configuration up until that element, the same way we substitute h for Planck's constant and c for the speed of light.
- Sun Oct 20, 2019 11:44 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing Electron Configurations
- Replies: 7
- Views: 324
Re: Writing Electron Configurations
I'm not sure whether or not it matters if you include it, because it means the same thing either way, but the x, y, and z only exists for p-orbitals.
- Sun Oct 20, 2019 11:40 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: configurations for p-orbital
- Replies: 3
- Views: 83
configurations for p-orbital
So I know for electron configurations you can write out the p-orbital configurations as, for example, either (p3) or (px1)(py1)(pz1); but which one are we supposed to use/which one is more correct/accurate?
- Sun Oct 20, 2019 11:38 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: 1A.15
- Replies: 2
- Views: 113
1A.15
I was trying to work through this problem with a friend and we couldn't figure it out so we looked at the solution guide, and for the most part it's understandable, except I can't figure out for the (1/n^2) equation how they got 3.29 x 10^15 s^-1 as the denominator?
- Sat Oct 12, 2019 12:51 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Negative Electrons vs Positive Nucleus
- Replies: 2
- Views: 144
Re: Negative Electrons vs Positive Nucleus
Bouncing off of the previous comment, electrons exhibit wavelike properties, which is what keeps them moving even when they lose energy, therefore preventing them from falling all the way down to the nucleus.
- Sat Oct 12, 2019 12:48 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Indeterminacy principle
- Replies: 3
- Views: 562
Re: Indeterminacy principle
There is a limit to the accuracy to which both momentum and position are known. In simple terms: it is extremely difficult to pinpoint the exact location of such a minuscule particle while it is moving. Inversely, it is not possible to know the momentum of that particle if it is stopped or slowed to...
- Sat Oct 12, 2019 12:44 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals as mathematical functions
- Replies: 1
- Views: 91
Orbitals as mathematical functions
During lecture on Friday, Professor Lavelle mentioned that orbitals are actually represented as wave functions and are therefore mathematical functions. Can someone clarify what that means, both theoretically and practically?
- Sat Oct 12, 2019 12:41 pm
- Forum: Properties of Electrons
- Topic: De Broglie Problems
- Replies: 4
- Views: 114
Re: De Broglie Problems
As the previous comments mentioned, any wavelength smaller than 10^-15 m is undetectable and would only show particle-like properties. The most important thing to remember is that the wavelength produced by the equation is directly influenced by the mass of the object in question. The larger the mas...
- Sat Oct 12, 2019 12:38 pm
- Forum: *Black Body Radiation
- Topic: Black Body Radiation
- Replies: 6
- Views: 364
Re: Black Body Radiation
A black body is a hypothetical concept because if such a thing were truly to exist, it would absorb and emit all electromagnetic radiation and therefore all visible light, making it invisible to the human eye. A good way to imagine it is as a smaller version of a black hole, as mentioned in the prev...
- Fri Oct 04, 2019 5:36 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Use of Avogadro's number
- Replies: 3
- Views: 173
Use of Avogadro's number
In conversions from moles to mass, we only use molar mass, and the given number of moles and mass, so when do we use Avogadro's number?
- Fri Oct 04, 2019 2:14 pm
- Forum: Balancing Chemical Reactions
- Topic: Strategies for Balancing Chemical Equations
- Replies: 12
- Views: 703
Strategies for Balancing Chemical Equations
I'm not sure how everyone else's high school chemistry experience was, but my teacher didn't really cover the material in depth, so I was wondering - is there any other/more efficient strategy to balance chemical equations other than trial and error? And if not, is there at least a strategic startin...
- Fri Oct 04, 2019 2:10 pm
- Forum: Empirical & Molecular Formulas
- Topic: Practical Difference between empirical and molecular formulas
- Replies: 2
- Views: 273
Practical Difference between empirical and molecular formulas
I understand the difference between empirical and molecular formulas, but what is the purpose of simplifying molecular formulas to empirical formulas? Because once you change the amounts/numbers of the individual elements, doesn't it change what compound it is? And if so, then what is the use of it/...
- Fri Oct 04, 2019 2:06 pm
- Forum: Significant Figures
- Topic: Sig Figs in Mulitstep Problems
- Replies: 10
- Views: 253
Re: Sig Figs in Mulitstep Problems
Also one thing to keep in mind is that most graphing calculators have a sig fig function if you're using those for homework problems, but we're not allowed to use those on exams, so it's probably better to just get in the habit of keeping more sig figs throughout the problem and then rounding at the...
- Fri Oct 04, 2019 1:59 pm
- Forum: Significant Figures
- Topic: Sig Figs given in problem vs solution
- Replies: 3
- Views: 172
Sig Figs given in problem vs solution
I was reading through the posts on this board but I thought I'd post myself just to clarify - does the number of sig figs you give in your solution have to match the number of sig figs that the given values in the problem have?