Search found 30 matches
- Sun Jun 10, 2018 7:39 pm
- Forum: Lewis Acids & Bases
- Topic: Given PH first
- Replies: 4
- Views: 709
Re: Given PH first
It is in terms of H3O+, but I believe that we consider them to be interchangeable as Professor Lavelle has mentioned in lecture.
- Sun Jun 10, 2018 7:38 pm
- Forum: Lewis Acids & Bases
- Topic: HW J9
- Replies: 2
- Views: 495
Re: HW J9
Yes! B is the correct answer, it can easily donate protons since there are no bonds to be broken in order to do so.
- Sun Jun 10, 2018 7:37 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis vs Bronsted
- Replies: 4
- Views: 580
Re: Lewis vs Bronsted
A key difference to remember is that the Lewis definition is based on electrons, while the Bronsted definition is based on protons.
- Sun Jun 03, 2018 8:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular shape
- Replies: 3
- Views: 466
Re: Molecular shape
You would visualize by the shape of the Lewis structure and number of lone pairs/bonded pairs. We only need to memorize the VSEPR shapes but not for each molecule.
- Sun Jun 03, 2018 7:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Textbook 4.21 part d
- Replies: 3
- Views: 451
Re: Textbook 4.21 part d
We only need to know when it is slightly less than 109.5 vs 109.5 because we cannot actually calculate the degree exactly.
- Sun Jun 03, 2018 7:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR formula with 2 central atoms
- Replies: 2
- Views: 471
Re: VSEPR formula with 2 central atoms
Also, if it were the case with central atoms with different VSEPR formulas, you would name them both.
- Sun May 27, 2018 9:23 pm
- Forum: Lewis Structures
- Topic: Writing Chemical Formulas- HW Question 3.25
- Replies: 2
- Views: 400
Re: Writing Chemical Formulas- HW Question 3.25
For these types of questions, I like to think of them as like balancing chemical equations. Explained above, there are a certain number of electrons needed to complete each octet. By recognizing this, you can multiply to find the formula. Hope this helps!
- Sun May 27, 2018 9:20 pm
- Forum: Lewis Structures
- Topic: Question 3.41
- Replies: 1
- Views: 277
Re: Question 3.41
For this one, I also had trouble. But, a few quick tips is that there are multiple easily attainable bonds. For example, if you start with NH2, H2C, and COOH as separate, you can bond them together by finding where electrons are needed. Hope this helps!
- Sun May 27, 2018 9:16 pm
- Forum: Lewis Structures
- Topic: Lone pair arrangement
- Replies: 4
- Views: 626
Re: Lone pair arrangement
You would just need to arrange them so that present the right amount of lone pairs for the atom, placement is not necessarily an important detail.
- Sun May 20, 2018 1:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: Phases of molecules
- Replies: 1
- Views: 283
Re: Phases of molecules
On the periodic table, the elements are in groups in which they exist. For example, you'll notice that the right side are noble gases and in the center of the periodic table there are metals. It is not necessarily memorization but remembering how the periodic table is structured!
- Sun May 20, 2018 1:18 pm
- Forum: Lewis Structures
- Topic: 3.41 c [ENDORSED]
- Replies: 4
- Views: 544
Re: 3.41 c [ENDORSED]
Those two are technically the same because you are still representing all electrons, just in different places. Both answers are correct, hope this helps!
- Sun May 20, 2018 1:15 pm
- Forum: Lewis Structures
- Topic: Cyclic Structure (S3N3)
- Replies: 1
- Views: 462
Re: Cyclic Structure (S3N3)
Yes, I am pretty sure that it will be noted when the structure is cyclic because it is crucial information! Hope this helps!
- Sun May 13, 2018 11:11 pm
- Forum: Trends in The Periodic Table
- Topic: 2.81
- Replies: 3
- Views: 504
Re: 2.81
Yes, because the electrons in the 2p orbital are unstable, Oxygen will want to gain or receive electrons badly making the ionization lower.
- Sun May 13, 2018 11:08 pm
- Forum: Trends in The Periodic Table
- Topic: Does Sulfur or Phosphorus have a larger ionization energy?
- Replies: 3
- Views: 13954
Re: Does Sulfur or Phosphorus have a larger ionization energy?
I think that sulfur has a higher ionization energy because generally ionization energy increases across the periodic table.
- Sun May 13, 2018 11:03 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 2.55 - what does valence-shell configuration mean?
- Replies: 3
- Views: 584
Re: 2.55 - what does valence-shell configuration mean?
Something else to remember for this is that the valence shell is the outermost electron. Hope this helps!
- Sun May 06, 2018 6:04 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Exceptions for electron configuration
- Replies: 3
- Views: 474
Re: Exceptions for electron configuration
For those exceptions mentioned above, it is because it is more stable being half-filled and fully filled, so the electron configuration is changed.
- Sun May 06, 2018 6:01 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Spin Direction [ENDORSED]
- Replies: 4
- Views: 771
Re: Spin Direction [ENDORSED]
We say spin up first when drawing the orbitals, but in reality it is not always the case that it is spin up.
- Sun May 06, 2018 5:55 pm
- Forum: Trends in The Periodic Table
- Topic: Stability of Cl vs Cl-
- Replies: 6
- Views: 2338
Re: Stability of Cl vs Cl-
Yes, because it now has a full octet it is more stable.
- Sun Apr 29, 2018 5:27 pm
- Forum: DeBroglie Equation
- Topic: 1.33 [ENDORSED]
- Replies: 2
- Views: 438
Re: 1.33 [ENDORSED]
Remember that 1J is also equal to 1 kg x m^2 x s^-2 . This will help with problems that use the De Broglie equation because usually the Joule is at the numerator, and cancels with the denominator providing the unit you need.
- Sun Apr 29, 2018 5:21 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectra Post Module #29 [ENDORSED]
- Replies: 3
- Views: 543
Re: Atomic Spectra Post Module #29 [ENDORSED]
What you calculated is joules per photon, so you would take the total energy emitted (11 J) and divide it by joules per photon, giving photons!
- Sun Apr 29, 2018 5:19 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg [ENDORSED]
- Replies: 4
- Views: 558
Re: Rydberg [ENDORSED]
I also had trouble with this in the beginning. If you think conceptually though, there can't be a negative frequency or wavelength, so I would remove it if it doesn't make sense to the concept.
- Sun Apr 22, 2018 8:09 pm
- Forum: Photoelectric Effect
- Topic: Work function [ENDORSED]
- Replies: 6
- Views: 846
Re: Work function [ENDORSED]
Another thing to add, it is the energy required to eject an electron. So, if the energy supplied by the photon is less than the work function, it will not eject the electron.
- Sun Apr 22, 2018 8:05 pm
- Forum: Properties of Light
- Topic: amplitude and intensity
- Replies: 11
- Views: 1113
Re: amplitude and intensity
Yes, I believe it will be covered because it will most likely be mentioned in a problem, but not specifically tested!
- Sun Apr 22, 2018 8:02 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect
- Replies: 4
- Views: 309
Re: Photoelectric Effect
It also proves that light is not just made of waves, which was previously thought. It is instead made of particles.
- Sun Apr 15, 2018 5:10 pm
- Forum: Balancing Chemical Reactions
- Topic: Chemistry Background [ENDORSED]
- Replies: 4
- Views: 589
Re: Chemistry Background [ENDORSED]
The review of high school chemistry is basically a basis to the rest of Chem 14A and the 14 series. It is important to know the concepts and how to do the problems as they will most likely be built on with later concepts. Hope this helped!
- Sun Apr 15, 2018 5:02 pm
- Forum: Significant Figures
- Topic: Purpose of Sig Figs
- Replies: 2
- Views: 334
Re: Purpose of Sig Figs
Significant figures are generally used to report accurate and exact amounts of what you are presenting. With significant figures, chemists can report findings more accurately to other chemists and compare accurate answers to their experiments. Hope this helped!
- Sun Apr 15, 2018 4:52 pm
- Forum: Balancing Chemical Reactions
- Topic: Suggestions for Balancing Reactions
- Replies: 8
- Views: 1019
Re: Suggestions for Balancing Reactions
What I usually do is pick an element that I can easily balance on each side. Then, I draw an arrow under the element with the number of moles of each element, and often check each one to make sure there is the same amount on each side. Another tip is to always do Oxygen (if it is in the equation) la...
- Sun Apr 15, 2018 4:49 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Atomic weight vs molecular weight
- Replies: 4
- Views: 959
Atomic weight vs molecular weight
What is the difference between atomic weight and molecular weight? And what are these terms needed for in terms of chemical reactions?
- Sun Apr 15, 2018 4:47 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Definition of Avogadro's number
- Replies: 3
- Views: 711
Re: Definition of Avogadro's number
Avogadro's constant is 6.0221 x 10^23 , meaning 1 mole of objects (really anything) is 6.0221 x 10^23 of those objects. This constant is helpful for converting moles to molecules, atoms, formula units.
- Sun Apr 15, 2018 4:30 pm
- Forum: SI Units, Unit Conversions
- Topic: Correct Units?? [ENDORSED]
- Replies: 8
- Views: 924
Re: Correct Units?? [ENDORSED]
Also, look at what units are given in the question. If they are stated in kilograms, you would generally give the answer in kilograms also, no matter how big or small the number is. And vice versa with grams.