Search found 30 matches

by Madison Hacker 1L
Sun Jun 10, 2018 7:39 pm
Forum: Lewis Acids & Bases
Topic: Given PH first
Replies: 4
Views: 312

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.
by Madison Hacker 1L
Sun Jun 10, 2018 7:38 pm
Forum: Lewis Acids & Bases
Topic: HW J9
Replies: 2
Views: 189

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.
by Madison Hacker 1L
Sun Jun 10, 2018 7:37 pm
Forum: Lewis Acids & Bases
Topic: Lewis vs Bronsted
Replies: 4
Views: 208

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.
by Madison Hacker 1L
Sun Jun 03, 2018 8:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape
Replies: 3
Views: 136

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.
by Madison Hacker 1L
Sun Jun 03, 2018 7:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook 4.21 part d
Replies: 3
Views: 118

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.
by Madison Hacker 1L
Sun Jun 03, 2018 7:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR formula with 2 central atoms
Replies: 2
Views: 115

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.
by Madison Hacker 1L
Sun May 27, 2018 9:23 pm
Forum: Lewis Structures
Topic: Writing Chemical Formulas- HW Question 3.25
Replies: 2
Views: 118

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!
by Madison Hacker 1L
Sun May 27, 2018 9:20 pm
Forum: Lewis Structures
Topic: Question 3.41
Replies: 1
Views: 76

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!
by Madison Hacker 1L
Sun May 27, 2018 9:16 pm
Forum: Lewis Structures
Topic: Lone pair arrangement
Replies: 4
Views: 181

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.
by Madison Hacker 1L
Sun May 20, 2018 1:28 pm
Forum: Ionic & Covalent Bonds
Topic: Phases of molecules
Replies: 1
Views: 61

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!
by Madison Hacker 1L
Sun May 20, 2018 1:18 pm
Forum: Lewis Structures
Topic: 3.41 c [ENDORSED]
Replies: 4
Views: 167

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!
by Madison Hacker 1L
Sun May 20, 2018 1:15 pm
Forum: Lewis Structures
Topic: Cyclic Structure (S3N3)
Replies: 1
Views: 143

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!
by Madison Hacker 1L
Sun May 13, 2018 11:11 pm
Forum: Trends in The Periodic Table
Topic: 2.81
Replies: 3
Views: 191

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.
by Madison Hacker 1L
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: 1237

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.
by Madison Hacker 1L
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: 261

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!
by Madison Hacker 1L
Sun May 06, 2018 6:04 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions for electron configuration
Replies: 3
Views: 142

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.
by Madison Hacker 1L
Sun May 06, 2018 6:01 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spin Direction [ENDORSED]
Replies: 4
Views: 249

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.
by Madison Hacker 1L
Sun May 06, 2018 5:55 pm
Forum: Trends in The Periodic Table
Topic: Stability of Cl vs Cl-
Replies: 6
Views: 240

Re: Stability of Cl vs Cl-

Yes, because it now has a full octet it is more stable.
by Madison Hacker 1L
Sun Apr 29, 2018 5:27 pm
Forum: DeBroglie Equation
Topic: 1.33 [ENDORSED]
Replies: 2
Views: 157

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.
by Madison Hacker 1L
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: 209

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!
by Madison Hacker 1L
Sun Apr 29, 2018 5:19 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg [ENDORSED]
Replies: 4
Views: 183

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.
by Madison Hacker 1L
Sun Apr 22, 2018 8:09 pm
Forum: Photoelectric Effect
Topic: Work function [ENDORSED]
Replies: 6
Views: 346

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.
by Madison Hacker 1L
Sun Apr 22, 2018 8:05 pm
Forum: Properties of Light
Topic: amplitude and intensity
Replies: 11
Views: 348

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!
by Madison Hacker 1L
Sun Apr 22, 2018 8:02 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 4
Views: 130

Re: Photoelectric Effect

It also proves that light is not just made of waves, which was previously thought. It is instead made of particles.
by Madison Hacker 1L
Sun Apr 15, 2018 5:10 pm
Forum: Balancing Chemical Reactions
Topic: Chemistry Background [ENDORSED]
Replies: 4
Views: 273

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!
by Madison Hacker 1L
Sun Apr 15, 2018 5:02 pm
Forum: Significant Figures
Topic: Purpose of Sig Figs
Replies: 2
Views: 145

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!
by Madison Hacker 1L
Sun Apr 15, 2018 4:52 pm
Forum: Balancing Chemical Reactions
Topic: Suggestions for Balancing Reactions
Replies: 8
Views: 371

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...
by Madison Hacker 1L
Sun Apr 15, 2018 4:49 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Atomic weight vs molecular weight
Replies: 4
Views: 268

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?
by Madison Hacker 1L
Sun Apr 15, 2018 4:47 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Definition of Avogadro's number
Replies: 3
Views: 238

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.
by Madison Hacker 1L
Sun Apr 15, 2018 4:30 pm
Forum: SI Units, Unit Conversions
Topic: Correct Units?? [ENDORSED]
Replies: 8
Views: 314

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.

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