Search found 58 matches
- Sun Dec 08, 2019 9:34 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 14A FInal
- Replies: 6
- Views: 485
Re: 14A FInal
Someone said this Friday at 5 but I am not sure how accurate that it
- Sun Dec 08, 2019 9:32 pm
- Forum: Student Social/Study Group
- Topic: thoughts on final exam
- Replies: 4
- Views: 404
Re: thoughts on final exam
and also how to switch majors
- Sun Dec 08, 2019 9:32 pm
- Forum: Student Social/Study Group
- Topic: thoughts on final exam
- Replies: 4
- Views: 404
Re: thoughts on final exam
Does anyone know when we will get our scores back
- Sun Dec 08, 2019 9:30 pm
- Forum: Administrative Questions and Class Announcements
- Topic: curve
- Replies: 8
- Views: 617
Re: curve
I have been wondering this too. All I know is 250/500 is considered a C- and then I think he is just gonna wait to see how the final average comes out and figure out the curve then
- Sun Dec 08, 2019 9:29 pm
- Forum: Significant Figures
- Topic: Sig Figs on Tests
- Replies: 24
- Views: 2117
Re: Sig Figs on Tests
for pH, the number of digits after the decimal point equates to the total number of sig figs for the concentration
- Sun Dec 08, 2019 3:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: THE SONG DJ LL PLAYS AT THE BEGINNING OF CLASS [ENDORSED]
- Replies: 7
- Views: 1050
Re: THE SONG DJ LL PLAYS AT THE BEGINNING OF CLASS [ENDORSED]
This is amazing
- Sun Dec 08, 2019 3:21 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: Titrations
- Replies: 6
- Views: 417
Re: Titrations
the stoichiometric point is when the moles of acid equals the moles of base, and knowing the volume and moles this can be used to calculate teh concentration and then the pH
- Sun Dec 01, 2019 11:59 pm
- Forum: Biological Examples
- Topic: cisplatin
- Replies: 3
- Views: 205
Re: cisplatin
Thank you for explaining , I was confused on this topic as well
Re: oxidation
The oxidation number comes after the metal atom in parenthesis
- Sun Dec 01, 2019 11:50 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: chelate
- Replies: 5
- Views: 372
Re: chelate
Does it involve ligands that are polydentates? and is cisplatin a chelate?
- Sun Dec 01, 2019 11:47 pm
- Forum: *Molecular Orbital Theory Applied To Transition Metals
- Topic: bond order
- Replies: 7
- Views: 929
Re: bond order
I think just a general sense of what it means in relation to bond strength and strength. So a bond order of 3, or a triple bond, is shorter and stronger than a bond order of 2, or a double bond
- Sun Dec 01, 2019 11:46 pm
- Forum: *Molecular Orbital Theory Applied To Transition Metals
- Topic: coordination sphere
- Replies: 1
- Views: 610
Re: coordination sphere
You use brackets to indicate what is inside the coordination sphere, or what is directly touching the central metal atom
- Sun Nov 24, 2019 7:38 pm
- Forum: Lewis Acids & Bases
- Topic: Donor and Acceptor
- Replies: 6
- Views: 316
Re: Donor and Acceptor
I was confused on this too, thank you!
- Sun Nov 24, 2019 7:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Intermolecular forces
- Replies: 5
- Views: 338
Re: Intermolecular forces
Ion- ion forces > ion-dipole forces > dipole-dipole > dipole - induced dipole > induced dipole -induced dipole. And then hydrogen bonds are basically just really strong dipole-dipole forces
- Sun Nov 24, 2019 7:29 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Bond order
- Replies: 5
- Views: 423
Re: Bond order
A double bond has a bond order of 2, a triple bond has a bond order of 3, etc...
- Sun Nov 24, 2019 7:26 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligands
- Replies: 5
- Views: 348
Re: Ligands
a ligand is an electron dense molecule
- Sun Nov 24, 2019 7:22 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma and Pi Bonds
- Replies: 7
- Views: 409
Re: Sigma and Pi Bonds
A sigma bond is a single bond and a double bond has one sigma and one pi bond
- Sun Nov 17, 2019 2:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: regions of electron density
- Replies: 10
- Views: 475
Re: regions of electron density
Why is knowing the number of regions of electron density necessary when naming a molecule? The number of regions of electron density affect the shape of the molecule, but the naming of the molecule comes from only the bonded atoms, not the lone pairs. So if a molecule has 4 regions of electron dens...
- Sun Nov 17, 2019 2:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR angles
- Replies: 4
- Views: 245
Re: VSEPR angles
Thank you so much!
- Sun Nov 17, 2019 2:45 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Structure of H2O
- Replies: 3
- Views: 201
Re: Structure of H2O
Lauren Sanchez 3D wrote:So if there are only two areas of electron density, that is when they are opposite of each other due to the strong repulsion?
Yes, I believe so because this minimizes the repulsions by putting the lone pairs farthest away from each other
- Sun Nov 17, 2019 2:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR angles
- Replies: 4
- Views: 245
VSEPR angles
Does anyone have any tips or tricks for remembering the angles for each shape?
- Sun Nov 17, 2019 2:42 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: 5
- Views: 249
Hydrogen Bonding
If a molecule, like NH3 for example, has a hydrogen bonded to an electronegative element does this mean there is hydrogen bonding? or does this hydrogen then have to be bonded to another electronegative atom in order for it to be a hydrogen bond?
- Sun Nov 17, 2019 2:34 pm
- Forum: Hybridization
- Topic: sp^3 orbital
- Replies: 3
- Views: 239
Re: sp^3 orbital
do we need to know this for the test?
- Sun Nov 10, 2019 11:43 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polar vs covalent
- Replies: 7
- Views: 387
Re: Polar vs covalent
EvanWang wrote:Covalent bonds occur between two nonmentals, while ionic bonds occur between a metal and a nonmetal.
does this infer that polar and ionic are interchangeable? You have me a little confused.
- Sun Nov 10, 2019 11:40 pm
- Forum: Coordinate Covalent Bonds
- Topic: coordinate covalent bond
- Replies: 7
- Views: 935
Re: coordinate covalent bond
It's a bond where both electrons come from one atom, completing the octet of an atom existing in a compound with an incomplete one. The example provided in class and in the textbook was that of boron trifluoride BF3, and boron has only six valence electrons. Its octet is completed when it forms a c...
- Sun Nov 10, 2019 11:39 pm
- Forum: Octet Exceptions
- Topic: elements in 3p block
- Replies: 8
- Views: 491
Re: elements in 3p block
Thank you guys for answering! This cleared up a lot for me!
- Sun Nov 10, 2019 11:39 pm
- Forum: General Science Questions
- Topic: Sig Figs
- Replies: 7
- Views: 427
Sig Figs
It's never been explicitly expressed, so I'm assuming that sig figs won't have any effect on grading on the test, but maybe I just missed when they said that. Are sig figs taken into account with points when grading?
- Sun Nov 10, 2019 11:36 pm
- Forum: General Science Questions
- Topic: Extra Credit
- Replies: 19
- Views: 747
Re: Extra Credit
aww that's a bummer... we just gotta grind hard boys
- Sun Nov 03, 2019 11:33 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Differences between polarizing power and polarizablity
- Replies: 2
- Views: 151
Re: Differences between polarizing power and polarizablity
Polarizability is the ability of an atom to have a distorted electron cloud. These are usually anions, and the larger they are the more likely it is for their electrons to be on one side at a moment in time. Polarizing power is the ability of an atom to induce this dipole moment and distort the elec...
- Sun Nov 03, 2019 11:30 pm
- Forum: Bond Lengths & Energies
- Topic: Short bond lengths vs long bond lengths
- Replies: 6
- Views: 427
Re: Short bond lengths vs long bond lengths
Shorter bond lengths are stronger because the distance between the atoms is smaller so they are pulling more tightly on each other, leading to a stronger bond. The longer the bond length and greater the distance between the two atoms, the weaker the nuclear force is holding these atoms together and ...
- Sun Nov 03, 2019 11:28 pm
- Forum: Octet Exceptions
- Topic: Radicals
- Replies: 5
- Views: 207
Re: Radicals
Radicals occur when there is an odd number of valence electrons, so there will be one unpaired electron. CH3 for example has 7 valence electrons so in the lewis structure there will only be one lone electron on the carbon. I think we just have to know what they are and how to identify them. Just bec...
- Sun Nov 03, 2019 11:27 pm
- Forum: Dipole Moments
- Topic: Dipole moments on Lewis structures
- Replies: 3
- Views: 238
Re: Dipole moments on Lewis structures
I think just with an arrow pointing towards the molecule with the partial negative charge
- Sun Nov 03, 2019 11:25 pm
- Forum: Lewis Structures
- Topic: double bonding with halogens
- Replies: 3
- Views: 137
double bonding with halogens
Do the halogens like fluorine and chlorine never form double bonds in lewis structures?
- Sun Nov 03, 2019 11:20 pm
- Forum: Octet Exceptions
- Topic: elements in 3p block
- Replies: 8
- Views: 491
elements in 3p block
Why are Phosphorus, Chlorine, and Sulfur exceptions to the octet rule when their electron configurations do not have a 3d orbital? Is it just because they are in the third energy level?
- Sun Nov 03, 2019 11:11 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: central atom
- Replies: 21
- Views: 913
central atom
Do we want to make it so that the central atom has a formal charge of zero?
- Sun Oct 27, 2019 11:55 pm
- Forum: Octet Exceptions
- Topic: More than 8 valence e-
- Replies: 8
- Views: 357
Re: More than 8 valence e-
Sulfur, phosphorous, and chlorine are examples of an expanded octet because starting in this row, these atoms have a d orbital which can hold extra electrons. In the normal state, they are not usually all filled so when it comes time to share electrons they are able to store more in the d orbital. H...
- Sun Oct 27, 2019 11:50 pm
- Forum: Trends in The Periodic Table
- Topic: Shielding and Electron Replusion
- Replies: 3
- Views: 527
Re: Shielding and Electron Replusion
They are different concepts I believe. Shielding occurs when the inner electrons block the outer electrons from the nuclear positive charge, which makes the outer electrons easier to remove. I would use this as a justification for ionization energy, but not atomic radius. Electron electron repulsion...
- Sun Oct 27, 2019 11:44 pm
- Forum: Administrative Questions and Class Announcements
- Topic: HW 4
- Replies: 2
- Views: 86
Re: HW 4
I think chemical bonds
- Sun Oct 27, 2019 11:44 pm
- Forum: Bond Lengths & Energies
- Topic: Double bond vs single bonds
- Replies: 4
- Views: 265
Re: Double bond vs single bonds
Double bond lengths are shorter than single bond lengths because double bonds are stronger, which means the force between the two atoms is going to increase, pulling them closer to each other. It would require more energy to break a double bond for this reason, because the atoms are closer together ...
- Sun Oct 27, 2019 11:41 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ground State
- Replies: 11
- Views: 489
Re: Ground State
So if an atom's electron configuration breaks one of the rules, like Hund's rule or Pauli exclusion principle, that means it is not in ground state but in excited state
- Sun Oct 27, 2019 11:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: 4s before 3d
- Replies: 4
- Views: 164
Re: 4s before 3d
Why is 3d at a lower energy level than 4s?
- Sun Oct 20, 2019 10:27 pm
- Forum: Trends in The Periodic Table
- Topic: Study Buddies?
- Replies: 8
- Views: 193
Re: Study Buddies?
yess! my email is narkeli17@gmail.com
- Sun Oct 20, 2019 11:15 am
- Forum: Photoelectric Effect
- Topic: The Work Function
- Replies: 15
- Views: 970
Re: The Work Function
Is the work function the same as the ionization energy then?
- Sun Oct 20, 2019 11:06 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: More Orbital Understanding
- Replies: 3
- Views: 151
Re: More Orbital Understanding
For p-orbitals, for example, it is unlikely to be near the nucleus because they have a nodal plane at the nucleus which means there is zero probability of finding an electron there. Due to the fact that p-orbitals, unlike s-orbitals, have angular momentum which pushes the electron away from the nucl...
- Sun Oct 20, 2019 10:59 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shell, Subshell, Orbital Terminology
- Replies: 8
- Views: 528
Re: Shell, Subshell, Orbital Terminology
So would it be correct to say that there are 3 p subshells in each shell or energy level?
- Sun Oct 20, 2019 10:51 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 4s vs. 3d
- Replies: 6
- Views: 209
Re: 4s vs. 3d
Why do electron-electron repulsions lead to 3d having higher energy?
- Sun Oct 20, 2019 12:34 am
- Forum: Trends in The Periodic Table
- Topic: ionization energy
- Replies: 11
- Views: 989
Re: ionization energy
The problem could just be asking to compare the ionization energies of two elements and state which is larger. The energy of a photon = ionization energy plus the kinetic energy so the value of the ionization energy could also be used here for a photoelectric effect problem.
- Sat Oct 12, 2019 8:49 pm
- Forum: Photoelectric Effect
- Topic: work function clarification
- Replies: 4
- Views: 132
Re: work function clarification
Are they only the same when the kinetic energy is zero? Or does this not matter
- Sat Oct 12, 2019 8:38 pm
- Forum: Properties of Light
- Topic: Wave Properties of Electrons
- Replies: 3
- Views: 173
Re: Wave Properties of Electrons
I think I'm still struggling with grasping the difference between diffraction and interference. Can someone please explain?
- Sat Oct 12, 2019 8:34 pm
- Forum: Properties of Light
- Topic: Wave Properties of electrons
- Replies: 7
- Views: 367
Re: Wave Properties of electrons
When waves encounter a barrier, like a wall, with small slits or openings, the waves will spread out past the openings and create these patterns as they interfere with one another. This is my understanding, I hope it helped!
- Sat Oct 12, 2019 8:24 pm
- Forum: Properties of Light
- Topic: Diffraction and Water
- Replies: 4
- Views: 169
Re: Diffraction and Water
Arianna Perea 3H wrote:Are diffractions only analyzed through the peaks of waves?
I think so because in order to analyze the interference patterns, you can look at the peaks of the waves to see if they are getting narrower, larger, etc.
- Sat Oct 12, 2019 8:15 pm
- Forum: Properties of Light
- Topic: Light intensity and Kinetic Energy
- Replies: 7
- Views: 375
Light intensity and Kinetic Energy
I am still kind of confused on why the kinetic energy does not change if the light intensity increases. Can someone please explain? Thanks!
- Mon Oct 07, 2019 9:21 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: G13
- Replies: 2
- Views: 278
G13
To prepare a fertilizer solution, a florist dilutes 1.0 L of 0.20 m NH4NO3(aq) by adding 3.0 L of water. The florist then adds 100. mL of the diluted solution to each plant. How many moles of nitrogen atoms will each plant receive? Solve this exercise without using a calculator. I used M1V1=M2V2 to ...
- Thu Oct 03, 2019 11:10 pm
- Forum: SI Units, Unit Conversions
- Topic: Help on Fundamentals: E21
- Replies: 7
- Views: 419
Re: Help on Fundamentals: E21
For E21a) in particular, you're converting 0.0981 moles of Al2O3 into molecules because Al2O3 is a molecular compound. If you were dealing with an element, however, like Al, you would be converting into atoms. In both cases though, you would use Avogadro's number to convert. I was a bit confused on...
- Thu Oct 03, 2019 10:58 pm
- Forum: Significant Figures
- Topic: subtracting with sig figs
- Replies: 5
- Views: 347
Re: subtracting with sig figs
So with adding and subtracting is the rule that the answer should have the same number of decimal places as the number with the least decimal places or should have the same number of sig figs overall as the number with the least number of decimal places?
- Thu Oct 03, 2019 10:50 pm
- Forum: Limiting Reactant Calculations
- Topic: M.11
- Replies: 3
- Views: 273
Re: M.11
I think everything is right up until the point where you convert 0.0406 moles O2 to grams of P4010. To get 5.77 grams, I multiplied 0.0406 moles O2 ( 1 mole P4O10 / 2 moles O2) (283.89 g / 1 mole). I think you just multiplied by 2 moles of O2 instead of dividing. Hope this helps!
- Thu Oct 03, 2019 8:27 pm
- Forum: Empirical & Molecular Formulas
- Topic: Rounding for Formulas
- Replies: 8
- Views: 408
Re: Rounding for Formulas
And the same applies for rounding down, right? For example, if after dividing I get 2.067 I can safely round down to 2
- Thu Oct 03, 2019 8:17 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student - Part II [ENDORSED]
- Replies: 298
- Views: 245165
Re: Advice from a Medical Student - Part II [ENDORSED]
Thank you so much for sharing your experience! I know getting letters of recommendation is a part of the application process, and I was wondering if you had any advice on how to get close and comfortable enough with professors to ask for a letter? I am also not 100% sure I want to follow this path a...