Search found 52 matches
- Thu Dec 05, 2019 10:29 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Identify chelate
- Replies: 2
- Views: 1470
Re: Identify chelate
What is the threshold for the bond angle of a chelating molecule? I have heard the term "spacer atom" but am not sure how this relates to whether a molecule can chelate.
- Wed Dec 04, 2019 12:07 am
- Forum: Bronsted Acids & Bases
- Topic: Homework Question
- Replies: 2
- Views: 242
Re: Homework Question
Also, this molecule is not likely to gain more protons because of its stability so it cannot be a Bronsted base (proton acceptor). If you look at the conjugate base SO3]2- this is a stable anion with resonance. It is a conjugate base of a strong acid which will completely dissociate in water and giv...
- Wed Dec 04, 2019 12:01 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Basic or Acidic
- Replies: 2
- Views: 263
Basic or Acidic
How can we determine if a molecule acts as an acid or a base if there are no hydrogens present in the formula? Is it solely based on the metal or nonmetal present or are there other ways of identifying its characteristics in an aqueous solution?
- Tue Dec 03, 2019 11:50 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric vs Amphiprotic
- Replies: 9
- Views: 594
Re: Amphoteric vs Amphiprotic
Amphiprotic means that a substance can both accept and donate a proton or H+. Amphoteric means that a substance can act as both an acid and a base. All amphoteric substances are amphiprotic because if a molecule can either donate or accept a proton, that means it can act as both an acid or a base. H...
- Tue Dec 03, 2019 11:45 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Hw 6C19
- Replies: 3
- Views: 213
Re: Hw 6C19
You can look at the anion once the acid has lost its proton and see which anion is more stable due to resonance of the structure or electronegativity, and in this case Chlorine is more electronegative than Phosphorus so chlorine stabilizes the anion more since it is able to withdraw the electrons.
- Tue Dec 03, 2019 11:35 pm
- Forum: Biological Examples
- Topic: hemoglobin and myoglobin
- Replies: 3
- Views: 446
Re: hemoglobin and myoglobin
Myoglobin has one heme group and primarily stores oxygen while hemoglobin has 4 heme groups and transports oxygen.
- Thu Nov 28, 2019 12:06 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test #2 handback
- Replies: 11
- Views: 730
Re: Test #2 handback
So if I am getting my test back in discussion Friday I will have two days to review it before the final?
- Thu Nov 28, 2019 12:04 pm
- Forum: Bronsted Acids & Bases
- Topic: Lewis and Bronsted
- Replies: 4
- Views: 286
Re: Lewis and Bronsted
A Lewis base means that molecule is donating its lone pair, while the Bronsted base accepts a proton. The molecule is still a base either way, it is just the way of wording that changes if its called Lewis or Bronsted.
- Thu Nov 28, 2019 12:01 pm
- Forum: Lewis Acids & Bases
- Topic: Identifying Acids and Bases
- Replies: 8
- Views: 485
Re: Identifying Acids and Bases
Strong acids are HCl, H2SO4, HI, HNO3, HBr, and HClO4, weak acids typically have carbon or phosphorus. Some of the strong bases are NaOH, Ba(OH)2, CsOH, and KOH, while weak bases typically have ammines. Nitrogen makes it a weak base because its lone pair can sometimes break the O-H bond in H2O.
- Thu Nov 28, 2019 11:53 am
- Forum: Amphoteric Compounds
- Topic: Amphoteric
- Replies: 8
- Views: 410
Re: Amphoteric
I just memorized which elements are amphoteric because the diagonal line is a bit skewed on the periodic table. However elements to the left of that general area are metals and form bases, while elements to the right are nonmetals and form acids.
- Thu Nov 28, 2019 11:48 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Week 9 homework
- Replies: 11
- Views: 758
Re: Week 9 homework
You would turn in week 9 and 10 at the same time during your next discussion.
- Thu Nov 28, 2019 11:47 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Cis vs Trans
- Replies: 22
- Views: 1784
Re: Cis vs Trans
Cis means same side and trans means opposite side, which also means that cis are typically polar charged because there is no cancellation of charges as opposed to trans.
- Mon Nov 18, 2019 8:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E13 part d
- Replies: 1
- Views: 149
2E13 part d
What is the correct way to draw the Lewis structure for N2O? There can either be a triple bond between the Nitrogen molecules and a single bond between Nitrogen and Oxygen, or a double bond between both N-N and N-O. Should the -1 formal charge be assigned to the Nitrogen atom or Oxygen?
- Mon Nov 18, 2019 8:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: XeF2 Bond Angle and Shape
- Replies: 2
- Views: 440
Re: XeF2 Bond Angle and Shape
The lone pair electrons spread out equidistant around the equatorial plane and the atoms, as a result, go to either end of the axial plane, as far away from each other as possible. The electron arrangement would appear trigonal bipyramidal while the molecular shape is linear. This is only possible w...
- Mon Nov 18, 2019 8:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Class Curve?
- Replies: 4
- Views: 351
Re: Class Curve?
I think Lavelle's curve will depend on the overall grades of the students in this quarter's 14A class the percent ranges for letter grades will be determined by his curve for this quarter.
- Mon Nov 18, 2019 8:47 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: Intermolecular Forces in CO2
- Replies: 4
- Views: 1622
Re: Intermolecular Forces in CO2
Since CO2 is a nonpolar molecule, only London dispersion forces are present and therefore would not have dipole-dipole forces. The behavior of the bonds within the molecule, also known as intramolecular forces, does not determine the type of intermolecular forces.
- Mon Nov 18, 2019 8:44 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2
- Replies: 7
- Views: 454
Re: Test 2
Just to be safe, I would suggest using bent as he taught us.
- Thu Nov 14, 2019 12:11 am
- Forum: Administrative Questions and Class Announcements
- Topic: Class grading
- Replies: 12
- Views: 811
Re: Class grading
I know that grades aren't assigned after everything is in the grade book, meaning that he can curve the grades if the average is low.
- Thu Nov 14, 2019 12:05 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: What’s the Difference
- Replies: 6
- Views: 559
Re: What’s the Difference
Polarizability is the tendency of an anion to be polarized, while polarizing power refers to how much cations can distort the electrons of the anion.
- Thu Nov 14, 2019 12:00 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Problem 2E 7
- Replies: 5
- Views: 345
Re: Problem 2E 7
005162520 wrote:How would you draw the resonance structure for SOCl2?
S is the central atom, double bonded to the Oxygen atom, single bonded to both Chlorine's, with a lone pair attached to the sulfur.
- Wed Nov 13, 2019 11:56 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: Intermolecular forces
- Replies: 10
- Views: 724
Re: Intermolecular forces
Most molecules have London forces, which occur between two dipoles, and are the weakest intermolecular forces relative to the others.
- Wed Nov 13, 2019 11:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E9
- Replies: 3
- Views: 268
Re: 2E9
The lone pair counts as an area of electron density which moves the atoms also bonded to the central atom as far away from each other as possible, which changes the molecule's shape.
- Tue Nov 05, 2019 10:44 am
- Forum: Lewis Structures
- Topic: Drawing Double Bonds
- Replies: 2
- Views: 246
Re: Drawing Double Bonds
First make sure the number of lone pairs + bonds on the atom matches the number of valence electrons or is very close so that it results in a low formal charge. Then check if you are maintaining the octet rule on the atoms to know which lone pairs must be taken away.
- Tue Nov 05, 2019 10:42 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: lyman and balmer
- Replies: 3
- Views: 233
Re: lyman and balmer
If the problem doesn't give you the n final if the electron is losing energy, or they don't give you n initial when an electron is going up levels, then you have to know that Balmer signifies n=2 and Lyman signifies n=1. These will then be plugged into the Rydberg formula to calculate the energy of ...
- Tue Nov 05, 2019 10:37 am
- Forum: Octet Exceptions
- Topic: Radicals
- Replies: 5
- Views: 244
Re: Radicals
After drawing the Lewis structure of a molecule you can usually identify a radical because one of the atoms has a single electron due to the odd number of valence electrons that must be accounted for.
- Tue Nov 05, 2019 10:35 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration
- Replies: 3
- Views: 352
Re: Electron Configuration
When writing electron configuration, 3d always preceeds 4s because it is a lower energy level!
- Tue Nov 05, 2019 10:28 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polar Covalent VS Ionic
- Replies: 11
- Views: 675
Re: Polar Covalent VS Ionic
Leila_4E wrote:This is really helpful, thank you. I'm also having trouble remembering if the ionic radius trend is different than atomic radius trend?
The ionic radius trend is the same as the atomic radius trend. Decreasing down and to the left.
- Wed Oct 30, 2019 10:23 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Question 1E 1
- Replies: 3
- Views: 225
Re: Question 1E 1
I don't think the fact that it is a Lithium atom is as significant in this problem as the fact that it is going from the 1s-orbital to the 2p-orbital. This is what tells you that energy will increase, the value of l and n will increase, and the radius will increase because electrons are being added.
- Wed Oct 30, 2019 10:19 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: d block before s block
- Replies: 3
- Views: 223
Re: d block before s block
I think this partly has to do with an electron being removed from 4s before it would be removed from 3d. The energy level is lower in the 3d shell, so it would come before 4s when 4s has both electrons.
- Wed Oct 30, 2019 10:16 am
- Forum: Ionic & Covalent Bonds
- Topic: Format of midterm?
- Replies: 12
- Views: 690
Re: Format of midterm?
I believe the entire test will be free response questions like the first one, but I am not 100% sure.
- Wed Oct 30, 2019 10:14 am
- Forum: Lewis Structures
- Topic: Formal charge
- Replies: 9
- Views: 276
Re: Formal charge
aphung1G wrote:Can someone explain how to find the lone pair electrons when trying to find the formal charge?
Whichever pairs of electrons that cannot be replaced by a bond when the Lewis structure is drawn out can be counted as a lone pair. It helps to see the picture in order to determine lone pair electrons.
- Wed Oct 30, 2019 10:10 am
- Forum: Ionic & Covalent Bonds
- Topic: Atomic and ionic radii
- Replies: 3
- Views: 216
Re: Atomic and ionic radii
Atomic radius is half the diameter measured across one ground state atom, while ionic radius is half the distance between the nuclei of two ionically bonded atoms.
- Wed Oct 23, 2019 8:58 pm
- Forum: DeBroglie Equation
- Topic: DeBroglie Equation
- Replies: 11
- Views: 381
Re: DeBroglie Equation
De Broglie's Equation proves wavelike properties of electrons by finding wavelength, and the equation is Planck's constant/(mass x velocity) is used for this.
- Wed Oct 23, 2019 8:43 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Subshell vs. Orbital
- Replies: 9
- Views: 1343
Re: Subshell vs. Orbital
n correlates to the shell; l correlates to the subshell; ml correlates to the orbital.
- Wed Oct 23, 2019 8:32 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student - Part II [ENDORSED]
- Replies: 298
- Views: 305169
Re: Advice from a Medical Student - Part II [ENDORSED]
I love your perspective on being able to take these classes at UCLA and how big of an opportunity this is for us and maybe our last opportunity to learn about this subject material! Thank you so much for sharing and good luck with the rest of your journey!!
- Wed Oct 23, 2019 8:26 pm
- Forum: Trends in The Periodic Table
- Topic: Electron affinity
- Replies: 5
- Views: 285
Re: Electron affinity
The elements in the top right of the periodic table have shells that are nearly full, meaning they need few electrons to complete an octet, whereas elements in the bottom left corner of the periodic table need to gain far more electrons in order to have an octet.
- Wed Oct 23, 2019 8:22 pm
- Forum: Trends in The Periodic Table
- Topic: Exceptions
- Replies: 3
- Views: 239
Exceptions
What are the exceptions to the trends in the periodic table when talking about ionization energy?
- Mon Oct 14, 2019 10:28 pm
- Forum: DeBroglie Equation
- Topic: DeBroglie
- Replies: 3
- Views: 224
Re: DeBroglie
His equation supports the fact that all matter -- if it is small enough -- has wavelike properties. Using Planck's constant and the momentum (mass*velocity) of the object, the wavelength of that object can be found because it has wavelike properties.
- Mon Oct 14, 2019 10:22 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 16
- Views: 971
Re: Atomic Radius
Atomic radii are only measured in the ground state, not in the excited state.
- Mon Oct 14, 2019 10:20 pm
- Forum: Properties of Electrons
- Topic: calculating frequency
- Replies: 3
- Views: 264
Re: calculating frequency
In terms of frequency, a negative value cannot be obtained because it is the number of waves over a given unit of time. Negative values represent the loss or gain of energy in terms of a change in energy under the Bohr frequency condition.
- Mon Oct 14, 2019 10:16 pm
- Forum: Student Social/Study Group
- Topic: De Broglie and Heseinberg
- Replies: 2
- Views: 135
Re: De Broglie and Heseinberg
The mass of one electron is 9.109*10^-28 grams
- Mon Oct 14, 2019 10:12 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Unit keV
- Replies: 4
- Views: 446
Re: Unit keV
Here is the conversion from keV to J:
E = (140.11*10^3 eV)*(1.6022*10^-19 J/eV) = 2.2513*10^-14 J
E = (140.11*10^3 eV)*(1.6022*10^-19 J/eV) = 2.2513*10^-14 J
- Fri Oct 11, 2019 1:23 am
- Forum: Properties of Light
- Topic: Emission/line spectrum
- Replies: 3
- Views: 188
Re: Emission/line spectrum
I think it is more conceptual, but also has to do with calculating the distances between spectral lines as was explained through the sketch during the last lecture. Visible light has smaller gaps between lines whereas ultraviolet has ones farther apart so the value of change in E is greater.
- Fri Oct 11, 2019 1:18 am
- Forum: DeBroglie Equation
- Topic: How to know which equation to use
- Replies: 9
- Views: 622
Re: How to know which equation to use
Both of those equations are referring to v as frequency instead of velocity, but you can use velocity in the equation E=1/2Me*Ve.
- Fri Oct 11, 2019 1:16 am
- Forum: Einstein Equation
- Topic: E=hv [ENDORSED]
- Replies: 52
- Views: 18558
Re: E=hv [ENDORSED]
E in this equation represents the energy of the photon. In some cases, it could also be equal to the energy required to remove an electron if the kinetic energy is 0. This is shown in the formula E(photon) - work function = Kinetic energy. If the Kinetic energy is 0, then the energy of the photon is...
- Fri Oct 11, 2019 1:12 am
- Forum: Empirical & Molecular Formulas
- Topic: Formula Units
- Replies: 10
- Views: 414
Re: Formula Units
Formula units are the amount of said material object, such as molecule, atom, compound, etc. The formula units are a quantitative measurement of the amount of any given thing.
- Fri Oct 11, 2019 1:10 am
- Forum: Photoelectric Effect
- Topic: Wavelengths?
- Replies: 8
- Views: 519
Re: Wavelengths?
The intensity of the photons hitting the metal surface is not as important as the frequency of the photons hitting the metal. Higher energy light results from the increased frequency, in other words a shorter wavelength, because all of these variables have a proportional relationship to one another.
- Thu Oct 03, 2019 9:58 pm
- Forum: SI Units, Unit Conversions
- Topic: How to format homework
- Replies: 9
- Views: 467
Re: How to format homework
On my paper is name, section and lecture #, date, and UID.
- Thu Oct 03, 2019 9:48 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: avogadro number
- Replies: 7
- Views: 747
Re: avogadro number
The number of units (atoms, molecules, compounds, etc.) in a mole.
- Thu Oct 03, 2019 9:47 pm
- Forum: Significant Figures
- Topic: Sig Figs on the Test
- Replies: 3
- Views: 195
Re: Sig Figs on the Test
You should use however many sig figs are given in the original problem, even when considering periodic table molar masses.
- Thu Oct 03, 2019 9:44 pm
- Forum: Balancing Chemical Reactions
- Topic: Compound names
- Replies: 11
- Views: 635
Re: Compound names
We will be given the necessary compound names on tests, so no we do not have to memorize them.
- Thu Oct 03, 2019 9:42 pm
- Forum: Limiting Reactant Calculations
- Topic: Basic Question
- Replies: 11
- Views: 578
Re: Basic Question
There can only be one limiting reactant in a chemical reaction. Sometimes the reactants are present in equal amounts so there would be none in this case.