Search found 38 matches

by timschaeffer Dis 1J
Sun Dec 09, 2018 6:19 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted acid
Replies: 4
Views: 219

Re: Bronsted acid

You can tell that Hbr is especially strong because Br is a halogen, meaning that it already wants to shed a hydrogen proton so it can gain an electron and become isoelectric with krypton. Br also has a relatively low electronegativity compared to other halogens like fluorine, so it holds less tightl...
by timschaeffer Dis 1J
Sun Dec 09, 2018 6:04 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination compound shape
Replies: 3
Views: 190

Re: coordination compound shape

the concept of "shape" in this case normally refers to that of the coordination sphere (whatever is inside the brackets for the coordination compound formula). Anything written outside the brackets is an ion or molecule that is closely associated with the coordination sphere but does influ...
by timschaeffer Dis 1J
Sun Dec 09, 2018 5:57 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: Strength
Replies: 5
Views: 225

Re: Strength

ion-ion interactions are stronger because the two species interaction both have concrete overall charges, while in an ion-dipole interaction only one species has an overall charge (ion) while the other species simply has unequally shared electrons resulting in a net dipole moment (dipole).
by timschaeffer Dis 1J
Sun Dec 09, 2018 5:46 pm
Forum: Properties of Light
Topic: Number of photons
Replies: 1
Views: 174

Re: Number of photons

I assume you mean laser and not labor. The energy per each photon is given by E= hc/wavelength, where h is planck's constant, c is the speed of light, and the wavelength is the wavelength of the laser. You then divide the energy of the laser by the energy per photon to get the number of photons bein...
by timschaeffer Dis 1J
Sun Dec 09, 2018 5:43 pm
Forum: Amphoteric Compounds
Topic: Examples
Replies: 5
Views: 166

Re: Examples

the oxides of As, Ge, Ga, In, Sn, Sb and Pb are also amphoteric compounds.
by timschaeffer Dis 1J
Thu Dec 06, 2018 8:13 pm
Forum: Octet Exceptions
Topic: Sulfur
Replies: 3
Views: 205

Re: Sulfur

it doesn't have to be consistent. When doing lewis structures for molecules like these, all that matters is that each molecule has at least an octet and the formal charges are relatively low. For S02, all that matters is that both oxygens and the sulfur have full octets (it doesn't matter that sulfu...
by timschaeffer Dis 1J
Thu Dec 06, 2018 7:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Naming Coordination compounds
Replies: 1
Views: 51

Re: Naming Coordination compounds

1) look at the total charge of the complex 2) then subtract the charges of all of the ligands (as if the ligands were not attached to the transition metal yet) from the total charge Whatever number is left is the charge of your transition metal, which is also its oxidation number in this case. If th...
by timschaeffer Dis 1J
Thu Dec 06, 2018 7:02 pm
Forum: Naming
Topic: K3[CoF6]
Replies: 2
Views: 59

Re: K3[CoF6]

the alphabetical rule only applies to the ligands attached to the transition metal. In general, the transition metal will always come after the ligands in the name.
by timschaeffer Dis 1J
Sun Dec 02, 2018 5:24 pm
Forum: Hybridization
Topic: Hybridization
Replies: 5
Views: 100

Re: Hybridization

yes because (number of regions of electron density) = (number of hybrid orbitals)
by timschaeffer Dis 1J
Sun Dec 02, 2018 5:20 pm
Forum: Hybridization
Topic: Hybrid Orbitals
Replies: 3
Views: 78

Re: Hybrid Orbitals

yes. each bond or lone pair around an atom can be added together to find the number of hybrid orbitals
by timschaeffer Dis 1J
Thu Nov 29, 2018 7:13 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: Is Hydrogen Bonding a type of Dipole-Dipole Interaction?
Replies: 5
Views: 120

Re: Is Hydrogen Bonding a type of Dipole-Dipole Interaction?

yes, hydrogen bonding is just a specific category under the larger umbrella of dipole-dipole interactions. If you say that hydrogen bonding exists between two molecules, then it generally goes without saying that there is an intermolecular dipole-dipole force between the molecules
by timschaeffer Dis 1J
Thu Nov 29, 2018 7:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR in equal angles
Replies: 4
Views: 97

Re: VSEPR in equal angles

This is only 100% true when all of the atoms attached to the central atom are of the same element. If the atoms are all different from one another, then the different dipole moments will likely result in a net dipole moment that makes the molecule polar, even if the geometric shape is symmetrical.
by timschaeffer Dis 1J
Thu Nov 29, 2018 7:05 pm
Forum: Naming
Topic: Brackets in Coordinate Compound Formula
Replies: 2
Views: 52

Re: Brackets in Coordinate Compound Formula

the species outside the brackets are not covalently bonded to anything in the coordination sphere, they are just closely associated with the coordination sphere due to intermolecular electrostatic forces
by timschaeffer Dis 1J
Wed Nov 28, 2018 11:57 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs on octahedral electron density
Replies: 3
Views: 78

Re: Lone pairs on octahedral electron density

due to the symmetry of the octahedral shape, it doesn't matter where the first atom is removed from (axial or equatorial) because it will always result in a square pyramidal shape
Octahedral-3D-balls.png
Octahedral-3D-balls.png (23.37 KiB) Viewed 75 times
by timschaeffer Dis 1J
Wed Nov 28, 2018 11:49 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles Preference
Replies: 2
Views: 62

Re: Bond Angles Preference

I think that the "less than 109.5" method would be preferred because vsepr cannot predict exact bond angles when lone pairs are involved.
by timschaeffer Dis 1J
Wed Nov 28, 2018 11:44 am
Forum: Hybridization
Topic: pi vs sigma
Replies: 12
Views: 235

Re: pi vs sigma

A pi bond's relative weakness can also be explained by the fact that, due to the parallel orientation of the p-orbitals involved in a pi bond, there is significantly less overlap between orbitals. sigma bonds, on the other hand, form bonding orbitals directly between the nuclei of the bonding atoms,...
by timschaeffer Dis 1J
Thu Nov 22, 2018 8:04 pm
Forum: Sigma & Pi Bonds
Topic: Carbon Pi bond hybridization
Replies: 2
Views: 55

Carbon Pi bond hybridization

Can someone explain to me what the aufbau diagram of a sp2 carbon looks like and how this hybridization allows the carbon to form pi bonds?
by timschaeffer Dis 1J
Thu Nov 22, 2018 7:45 pm
Forum: Dipole Moments
Topic: Dispersion Forces vs Van der Waals Reactions
Replies: 2
Views: 87

Re: Dispersion Forces vs Van der Waals Reactions

There may be nuanced differences between the two terms, but I remember specifically in class that Professor lavelle said that "Dispersion" "London" "van der waals" and "induced dipole-induced dipole" forces are all essentially synonymous. I don't think we need...
by timschaeffer Dis 1J
Thu Nov 22, 2018 7:38 pm
Forum: Dipole Moments
Topic: Intermolecular interactions 3F.1 (7th edition)
Replies: 1
Views: 64

Re: Intermolecular interactions 3F.1 (7th edition)

As a rule of thumb: 1) london dispersion forces will exist between any two non-polar molecules 2) dipole-induced dipole forces will exist to some extent between any polar molecule and any non-polar molecule 3) dipole-dipole interactions will exist between any two polar molecules. Essentially you nee...
by timschaeffer Dis 1J
Thu Nov 22, 2018 7:31 pm
Forum: Hybridization
Topic: Hybridization and drawing
Replies: 3
Views: 66

Re: Hybridization and drawing

the hybridization (sp, sp2, sp3, etc) will be able to tell you how many regions of electron density there are around an atom, which you can use to check your answer for your VSEPR and lewis drawings. In general, it is easier to get the right lewis drawing (because this is a more basic concept), and ...
by timschaeffer Dis 1J
Thu Nov 15, 2018 11:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion Strength
Replies: 7
Views: 109

Re: Repulsion Strength

It means that when lone pair electrons are attached to the central atom of a molecule, that VSEPR has no specific formulas that will give you the exact numerical (quantitative) angle values for that specific molecule. The exact angle values in this case can only be determined experimentally. VSEPR i...
by timschaeffer Dis 1J
Thu Nov 15, 2018 11:10 pm
Forum: Ionic & Covalent Bonds
Topic: Polar/non polar molecules
Replies: 5
Views: 119

Re: Polar/non polar molecules

Molecules are non-polar if they: A) consist entirely of atoms of the same element B) consist of a central atom of element 1 and a set of attached atoms that are all element 2, but the element 2 atoms are all symmetrically spaced around the molecule Molecules are generally polar if they: A) consist o...
by timschaeffer Dis 1J
Thu Nov 15, 2018 10:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 3
Views: 71

Re: Lone Pairs

When a central atom has multiple lone pairs, they don't necessarily have to be opposite of one another. This is because sometimes multiple other atoms attached to the central atom will end up pushing the two lone pairs into an orientation where they are closer together. The table below shows some ex...
by timschaeffer Dis 1J
Thu Nov 15, 2018 10:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Single Regions?
Replies: 8
Views: 157

Re: Single Regions?

The concept that single, double, and triple bonds are all "single regions" of electron density just means that, when using the VSEPR notation, all individual bonds (whether they are single, double or triple) count as 1 "X" . For example, a central atom attached to two other atoms...
by timschaeffer Dis 1J
Thu Nov 15, 2018 10:16 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ch.3 #19 (6th Edition)
Replies: 2
Views: 78

Re: Ch.3 #19 (6th Edition)

It helps me to think about it this way: The electrons farthest away from the nucleus will be taken away from the atom first (because they are further away from the nucleus attractive positive charge and therefore less tightly held). The electrons in the highest energy shell are always the furthest a...
by timschaeffer Dis 1J
Thu Nov 08, 2018 9:49 pm
Forum: Ionic & Covalent Bonds
Topic: Dipole and Dipole Moments
Replies: 2
Views: 59

Re: Dipole and Dipole Moments

A dipole is an atom or molecule with both a partial positive region and a partial negative region. A dipole moment is a value that describes two opposite charges separated by some distance. If a molecule has a dipole moment, then it is polar. The bigger the dipole moment, the more polar the molecule.
by timschaeffer Dis 1J
Thu Nov 08, 2018 9:35 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula Problem Solving
Replies: 2
Views: 295

Empirical Formula Problem Solving

When solving for the empirical formula, what do you do when you have the moles of each atom but they're all really close in value or don't seem to follow any obvious ratio? I wasted a lot of time on this final step during the midterm. Does anyone have any good strategies for finding the answer quick...
by timschaeffer Dis 1J
Thu Nov 08, 2018 9:05 pm
Forum: Electronegativity
Topic: Hydrogen electronegativity
Replies: 3
Views: 70

Re: Hydrogen electronegativity

Electronegativity increases as you go across a period and as you go down a group. Based on the graph, it looks like electronegativity is more heavily effected by going across a group. This might explain why flourine (on the far right of the table) is more electronegative than hydrogen (on the far le...
by timschaeffer Dis 1J
Thu Nov 01, 2018 10:19 pm
Forum: Electronegativity
Topic: What are the trends useful for?
Replies: 12
Views: 160

Re: What are the trends useful for?

The IE and EA trends are also important when making lewis structures because the atom with the lowest ionization energy (or the lowest electron affinity) should be used as the central atom.
by timschaeffer Dis 1J
Thu Nov 01, 2018 9:53 pm
Forum: Octet Exceptions
Topic: H, He, Li, Be Rule
Replies: 3
Views: 88

Re: H, He, Li, Be Rule

Another way to think about it is that to have 8 valence electrons for an octet you need to have at least an s-orbital (2 electrons) and a p-orbital(6 electrons) in the outermost energy shell. The first 4 elements fill up as far as the 1s and 2s orbitals but never reach any p-orbital at all. Trying t...
by timschaeffer Dis 1J
Thu Nov 01, 2018 9:38 pm
Forum: Octet Exceptions
Topic: ClO2 Radical
Replies: 1
Views: 43

Re: ClO2 Radical

The whole molecule is considered a radical. In terms of chemical properties, this just means that it is highly reactive because having an unpaired valence electron is a very unstable state.
by timschaeffer Dis 1J
Tue Oct 23, 2018 8:45 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 2
Views: 51

Re: Electron Configurations

It looks like the same exception applies for Mo but not for Ag (according to the periodic table in the front of the Chemical Principles book). I don't have a good explanation as to why this is.
by timschaeffer Dis 1J
Tue Oct 23, 2018 5:28 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: f-orbitals
Replies: 2
Views: 85

Re: f-orbitals

Using the old high school chemistry diagonal rule, it looks like the 4f orbital just starts to get filled after 6s. This corresponds to everything after Lanthanum. The Lanthanoids (the top row of the purple box) show how the 4f orbital fills up from Cerium through to Lutetium. With the scope of this...
by timschaeffer Dis 1J
Tue Oct 23, 2018 5:03 pm
Forum: Properties of Light
Topic: EM Energy Spectrum
Replies: 4
Views: 144

Re: EM Energy Spectrum

It obviously wouldn't hurt if you knew those values off the top of your head, but I don't remember Professor Lavelle stating specific wavelengths other than the general range for visible light (400nm-700nm) and UV(100nm-400nm). I also don't remember Professor Lavelle saying that it was important to ...
by timschaeffer Dis 1J
Thu Oct 18, 2018 10:54 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 2
Views: 48

Re: Nodal Planes

Here's another figure with the nodal planes included
Nodal Planes.jpg
by timschaeffer Dis 1J
Thu Oct 18, 2018 10:51 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 2
Views: 48

Re: Nodal Planes

D_orbitals.png


I'm not sure what you mean by nodal lobes but I attached a file that shows all of the configurations for the d-orbitals (hopefully the file shows up)
by timschaeffer Dis 1J
Thu Oct 18, 2018 10:21 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Wave Functions
Replies: 2
Views: 30

Wave Functions

I'm still a little confused on what the wave function of an electron in an atom represents. Do they represent the position of the electron or its energy?
by timschaeffer Dis 1J
Thu Oct 04, 2018 7:06 pm
Forum: Limiting Reactant Calculations
Topic: Limiting reactant [ENDORSED]
Replies: 2
Views: 63

Re: Limiting reactant [ENDORSED]

What matters most for these problems is that you know: 1) how many atoms/molecules/moles of each reactant you have at the beginning of the process, and 2) how many atoms/molecules/moles of each reactant are consumed for each cycle of the chemical reaction Some reactants might be naturally heavier th...

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