## Search found 32 matches

Fri Jun 08, 2018 10:24 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination number=polydentate number?
Replies: 5
Views: 279

### Re: coordination number=polydentate number?

Thanks guys, I think that if there are multiple ligands on the metal, though, that the polydentate number of each ligand does not necessarily equal the coordination number of the whole complex. I definitely have to think about this more.
Thu Jun 07, 2018 7:46 pm
Forum: Calculating the pH of Salt Solutions
Topic: How temperature affects pH
Replies: 3
Views: 823

### How temperature affects pH

Why and how does temperature affect pH?
Thu Jun 07, 2018 7:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination number=polydentate number?
Replies: 5
Views: 279

### coordination number=polydentate number?

Does the number of coordination bonds in a coordination compound always equal the number of bonds that a ligand makes with the central metal atom (polydentate number)?
Thu May 31, 2018 6:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double bond
Replies: 3
Views: 201

### Re: Double bond

Hi Melissa,
So pi bonds do have overlaps in 2 places, but these are considered just 2 regions of 1 bond. I guess this is because there are only 2 electrons involved (1 from one p and 1 from the other p).
Thu May 31, 2018 6:08 pm
Forum: Hybridization
Topic: Hybridization
Replies: 2
Views: 152

### Re: Hybridization

To add on, the "correct" number of hybridization orbitals is a consequence of the atom reaching minimal energy when it forms a bond. Atomic orbitals hybridize when the atom is bonding to other atoms, so that the atom can be less energetic.
Thu May 31, 2018 5:58 pm
Forum: Hybridization
Topic: Why # regions of e density= # atomic orbitals?
Replies: 3
Views: 228

### Re: Why # regions of e density= # atomic orbitals?

Thanks Beverly! This sentence "The 2p3 shell is a mix of the 2s shell (1 orbital) and 2p shell (3 orbitals) so it has 4 hybrid orbitals." was particularly helpful. More specifically, I'm wondering why there are necessarily 4 ways (hybrid orbitals) to mix 4 atomic orbitals.
Thu May 31, 2018 5:31 pm
Forum: Hybridization
Topic: Why # regions of e density= # atomic orbitals?
Replies: 3
Views: 228

### Why # regions of e density= # atomic orbitals?

I was interested in this fact from Wednesday's lecture. The number of atomic orbitals in an atom is the same as the number of regions of electron density that appear when the atom participates in bonding. Is this just a really cool coincidence? Why is this? A key part in my question is about why the...
Fri May 25, 2018 10:48 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing power
Replies: 10
Views: 3383

### Re: Polarizing power

Also, small and highly charged cations have high polarizing power while large anions have high polarizability (distorted easily).
Thu May 24, 2018 6:21 pm
Forum: Ionic & Covalent Bonds
Topic: Polar Vs. Non-Polar
Replies: 7
Views: 427

### Re: Polar Vs. Non-Polar

The difference in electronegativity of the atoms involved in the bond determines polarity. Difference in electronegativity means the electrons like to hang out closer to one atom than to the other, and this is called polar. When there is no difference in electronegativity (bond between atoms of the ...
Sun May 20, 2018 11:49 am
Forum: Dipole Moments
Topic: Why fluctuations? [ENDORSED]
Replies: 2
Views: 191

### Re: Why fluctuations?[ENDORSED]

Oh that makes sense. When molecules move around they change where attractions and repulsions are located. This changes the orientation of dipoles and causes constant fluctuation. I think I get it, thanks!
Sun May 20, 2018 11:39 am
Forum: Octet Exceptions
Topic: Empty d-orbital?
Replies: 2
Views: 268

### Empty d-orbital?

I'm a bit confused about this phrase "empty d-orbital", because earlier in the course I got the sense that orbitals are states that electrons can be in, rather than locations. My understanding is that when an atom has no electrons in a d-orbital state, then the d-orbital does not exist for...
Sun May 20, 2018 11:32 am
Forum: Dipole Moments
Topic: Why fluctuations? [ENDORSED]
Replies: 2
Views: 191

### Why fluctuations?[ENDORSED]

In induced dipole-induced dipole interactions, fluctuations in electron probability cloud density in one molecule causes complementary fluctuations in a nearby molecule. Why are there fluctuations in the electron cloud to begin with, and why doesn't the system equilibrate until both molecules are st...
Sun May 20, 2018 11:24 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Trends of Polarizing Power
Replies: 4
Views: 7572

### Re: Trends of Polarizing Power

Is it true that cations and anions have opposite polarizability trends?
Sun May 20, 2018 11:20 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Polarizability and boiling point
Replies: 2
Views: 1540

### Re: Polarizability and boiling point

Hi,
High polarizability means more covalent character,which means tighter bonding, and therefore means high boiling point. Please correct me if I'm wrong, I'm not quite sure either.
Sun May 13, 2018 10:40 am
Forum: Lewis Structures
Topic: Multiple Central atoms
Replies: 1
Views: 202

### Re: Multiple Central atoms

It is possible to have multiple central atoms. Though I'm not sure how you would go about making the lewis structure for that kind of molecule.
Sun May 13, 2018 10:35 am
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 4
Views: 316

### Re: Lewis Structures

I'm not sure. I think as long as the formal charges of all the atoms in your structure are as close as possible to zero, you're fine.
Sun May 13, 2018 10:34 am
Forum: Ionic & Covalent Bonds
Topic: 3.33
Replies: 5
Views: 303

### Re: 3.33

Hi,
Ionization energy increases across periods and decreases down columns. Keep this in mind when deciding which element has the lowest ionization energy (it will be closer to the lower left corner of the periodic table).
Fri May 04, 2018 9:28 pm
Forum: Properties of Electrons
Topic: Exciting Electrons
Replies: 2
Views: 341

### Re: Exciting Electrons

Yes, and if the electrons are being added to the same shell (as in moving across the periodic table) then the radius of the atom actually decreases because the electrons are being pulled in by increased effective nuclear charge.
Fri May 04, 2018 8:42 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 4s orbital
Replies: 2
Views: 173

### Re: 4s orbital

So to my understanding, 4s is lower in energy than 3d for s-block elements because the s orbital shape is a sphere and is "simpler" or lower in energy than the complicated energetic shape of the p orbital. 4s electrons are removed first though, because they are farther from the nucleus tha...
Fri May 04, 2018 8:35 pm
Forum: DeBroglie Equation
Topic: Bohr vs Speed of Light Equation
Replies: 3
Views: 232

### Re: Bohr vs Speed of Light Equation

Hi,
Both are good, it just depends on what information you are given. Typically, questions about the relationship between wavelength and frequency are best solved with c=lambda*nu. And questions about the energy of a photon are best solved with E=h*nu.
Sat Apr 28, 2018 5:58 pm
Forum: Photoelectric Effect
Topic: What is work function? [ENDORSED]
Replies: 15
Views: 3361

### Re: What is work function?[ENDORSED]

An important point is that it is the amt. of energy required to remove an electron from an atom such that it comes off with zero kinetic energy. There's no energy left over to move the electron away from the atom, only enough to detach it.
Sat Apr 28, 2018 5:49 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1.43 [ENDORSED]
Replies: 1
Views: 130

### Re: 1.43[ENDORSED]

The second part just means that the uncertainty in the electron's position is the diameter of the atom. In other words, the electron can occupy any position along this imaginary 350 pm long 1D box (which is a line). The book uses this box analogy that's kind of confusing, but that's what it means fo...
Sat Apr 28, 2018 5:43 pm
Forum: Quantum Numbers and The H-Atom
Topic: What do l and m represent? [ENDORSED]
Replies: 6
Views: 455

### Re: What do l and m represent?[ENDORSED]

l is the angular momentum quantum number and it determines the shape of the orbital. m is the magnetic quantum number and it determines the orientation of the orbital.
Fri Apr 20, 2018 7:20 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg’s formula
Replies: 1
Views: 145

### Re: Rydberg’s formula

What Professor Lavelle did was the exact same thing as the Rydberg equation. He took the difference in energies at the two levels. If you look at the Rydberg equation, you'll see that that's what it does. The constants look different just because they're rearranged, but they are the same. I recommen...
Fri Apr 20, 2018 7:12 pm
Forum: DeBroglie Equation
Topic: Photons? [ENDORSED]
Replies: 4
Views: 343

### Re: Photons?[ENDORSED]

I'm unclear on why E=h/p can't be used for photons. After all, photons do have momentum p and E=h/p is derived from equations that describe photons, so why doesn't E=h/p also describe photons? Photons don't have mass but they do have momentum, so I don't see why E=h/p can't be used for photons. I'm ...
Fri Apr 20, 2018 7:04 pm
Forum: Photoelectric Effect
Topic: Plastic vs Metal [ENDORSED]
Replies: 3
Views: 275

### Plastic vs Metal[ENDORSED]

We discussed this in class today, but I'm still unsure of the reason why plastic can't be used for the experiment. Is it because the experimental setup requires a conductive material, or is it because plastics (and other non-conductive materials) don't emit photons? thanks
Sat Apr 14, 2018 9:45 am
Forum: Properties of Electrons
Topic: Electromagnetic Field [ENDORSED]
Replies: 7
Views: 455

### Re: Electromagnetic Field[ENDORSED]

The E-M fields are perpendicular to each other always while they oscillate. The electric field can oscillate up and down if the magnetic field oscillates right and left. These oscillations form the light wave.
Sat Apr 14, 2018 9:33 am
Forum: *Black Body Radiation
Topic: Black Body? [ENDORSED]
Replies: 13
Views: 1477

### Re: Black Body?[ENDORSED]

Fun fact related to this topic: the Sun is a really efficient black body.
Sat Apr 14, 2018 9:23 am
Forum: Photoelectric Effect
Topic: Post module quiz #25
Replies: 6
Views: 215

### Re: Post module quiz #25

I also think the answer is D, because it directly relates energy E to frequency $\nu$.
Fri Apr 06, 2018 5:17 pm
Forum: Limiting Reactant Calculations
Topic: Module 3: Limiting Reactant Calculations Problem 21 [ENDORSED]
Replies: 2
Views: 138

### Re: Module 3: Limiting Reactant Calculations Problem 21[ENDORSED]

Hi, I think you forgot to balance the equation. With the balanced equation, the limiting reactant will be the same as what you found, but you will have a different molar ratio to work with to find the mass of AgCl.
Fri Apr 06, 2018 4:56 pm
Forum: Balancing Chemical Reactions
Topic: Subscripts [ENDORSED]
Replies: 6
Views: 488

### Re: Subscripts[ENDORSED]

Remember that subscripts indicate that the atoms are bonded to form a molecule while coefficients just count the molecules. For example, 6C4 represents 6 molecules (or moles) of C4.
Fri Apr 06, 2018 4:42 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Why does carbon have molar mass 12.011g/mol? [ENDORSED]
Replies: 1
Views: 205

### Why does carbon have molar mass 12.011g/mol?[ENDORSED]

Hello!
The definition of a mole is the number of atoms in exactly 12 g of carbon, and it follows that the mass of 1 mole of carbon should be exactly 12g. So, I'm confused about why the molar mass of carbon is 12.011 g/mol. Could anyone help explain this to me?
Thanks,
Mei

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