## Search found 29 matches

Sun Dec 02, 2018 11:52 pm
Forum: Hybridization
Topic: tetrahedral
Replies: 5
Views: 95

### Re: tetrahedral

Tetrahedral is an atom that has 4 bonds. This means that the 2s orbital and the 2p orbital hybridize to form sp3. To determine a molecule's hybridization, just count the number of bonds/lone pairs on the central atom (1 bond= s, 2 bond= sp, 3 bond= p2, 4 bond= sp3, 5 bond= sp3d, 6 bond= sp3d2, etc.)
Sun Dec 02, 2018 11:47 pm
Forum: Administrative Questions and Class Announcements
Replies: 10
Views: 225

I'm not 100% sure but I think the class is just graded on that rubric and not curved.
Sun Dec 02, 2018 11:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs angular?
Replies: 15
Views: 216

### Re: Bent vs angular?

They are the same but for exams, I would use bent for 2 bonds and one lone pair and angular for when it is 1 bond and 3 lone pairs.
Sun Nov 25, 2018 11:44 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bonds
Replies: 3
Views: 70

### Re: Bonds

The first covalent bond between atoms is a sigma bond. You can only have one sigma bond between two atoms. A single bond has one sigma, a double bond has one sigma and one pi. Pi bonds usually occur in p-orbitals (never s orbitals).
Sun Nov 25, 2018 11:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR model
Replies: 4
Views: 70

### Re: VSEPR model

The A tells us which is the central atom, the X tells us the ligands/bonds attached to the central atom, and E tells us the nonbonding electron pairs (and lowercase e shows nonbonding lone electrons). So, for example, AX2E could be SO2 because S is the central atom, it has two bonds with two Os, and...
Sun Nov 25, 2018 11:30 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Exam
Replies: 22
Views: 480

### Re: Final Exam

I asked a few students that have taken the class before and they said that is cumulative, but there won't be so many questions on the first few weeks material. For studying, I would suggest focusing mostly on the material after the midterm, but definitely do practice questions/ review all weeks mate...
Sun Nov 18, 2018 11:01 pm
Forum: Hybridization
Topic: Bond Angles
Replies: 12
Views: 208

### Re: Bond Angles

I assume that for the next exam/final, we will only be asked to determine the bond angles when also asked to draw the Lewis Structure for partial points. So, you'd draw the dot structure then determine the VSEPR shape and corresponding bond angles. Finding the dot structure is really important becau...
Sun Nov 18, 2018 10:56 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: 7
Views: 176

### Re: Intermolecular Forces

Non-polar molecules are attracted through London forces and polar molecules are attracted as well, but stronger through dipole-dipole attractions. So to determine, look at the electronegativity of the molecule. Also, size can help determine. Smaller molecules tend to have stronger dipole- dipole for...
Sun Nov 18, 2018 10:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma/Pi bonds
Replies: 7
Views: 117

### Re: Sigma/Pi bonds

Yes I agree there can only be one sigma bond between two atoms in a molecule and two in a pi bond, but in one molecule there can be multiple.
Mon Nov 12, 2018 12:03 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: Hydrogen Bonding [ENDORSED]
Replies: 3
Views: 83

### Re: Hydrogen Bonding[ENDORSED]

The amount of electronegativity of the hydrogen bond will make it the strongest.
Mon Nov 12, 2018 12:00 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: States of matter and forces
Replies: 3
Views: 105

### Re: States of matter and forces

Solids have the lowest kinetic energy (because their particles are moving the slowest) so they are closely attracted to each other. So solids have the highest intermolecular force because their particles are attracted to each other the most. Then liquid, then gas.
Sun Nov 11, 2018 11:53 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: Bond energy value signs
Replies: 3
Views: 126

### Re: Bond energy value signs

Yes I agree. Energy is released to break bonds, so it is positive. It is leaving the system. Energy is needed to make bonds, so it is negative. It is using up energy around to break it.
Mon Nov 05, 2018 12:10 am
Forum: Bond Lengths & Energies
Topic: Bond Lengths
Replies: 3
Views: 87

### Re: Bond Lengths

I think if he asks a question about bond lengths it will be referring to the overall trends/ how each atom connects to each other (polar, nonpolar, ionic).
Mon Nov 05, 2018 12:07 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge SO42-
Replies: 3
Views: 482

### Re: Formal Charge SO42-

After creating the Lewis Structure for the question, always do the formal charges around it to make sure that they are as close to 0 as possible! Even though it might look like it adds up and makes sense it may not be stable. In this example, the single bonded oxygens are unstable because they still...
Mon Nov 05, 2018 12:00 am
Forum: Octet Exceptions
Topic: What are the octet exceptions?
Replies: 9
Views: 205

### Re: What are the octet exceptions?

Also, P, S, and cl are specific exceptions that Dr. Lavelle said we needed to know for the exam that take more than 8 valence electrons!
Sun Nov 04, 2018 11:57 pm
Forum: *Crystal Field Theory
Topic: Electric Field
Replies: 2
Views: 1188

### Re: Electric Field

The crystal field theory explains how electron orbitals (usually d or f) get broken down by a static electric field. This field is created by anions to help take the electrons of these subshells and thus break it down. This is dependant on the shape of the orbital as well as its charge.
Sun Oct 28, 2018 10:16 pm
Forum: DeBroglie Equation
Topic: DeBroglie Equation Post Assessment
Replies: 4
Views: 192

### Re: DeBroglie Equation Post Assessment

The answers above give you the correct answer, but just make sure that you use parenthesis in your calculator! I know that in my experience I sometimes get the wrong answer when I'm dividing by something like Planck's Constant, it can get confusing if you are dividing while multiplying by 10^34, so ...
Sun Oct 28, 2018 10:13 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ionization of elements
Replies: 3
Views: 95

### Re: Ionization of elements

This is because that each element is different in the number of electrons it wants to take/give away when bonding. So for Cu, it has 2 valence electrons, so it would want to give up those 2 to make it stable, but not more than is in its valence ring. It also might want to take electrons to make it s...
Sun Oct 28, 2018 10:10 pm
Forum: *Shrodinger Equation
Topic: Application of Equation on test
Replies: 5
Views: 294

### Re: Application of Equation on test

I think we only need to know the conceptual ideas about this equation/how it's used/why it's important in chemistry, but we won't need to compute it.
Sun Oct 28, 2018 10:07 pm
Forum: Lewis Structures
Topic: Dots in Lewis Stucture
Replies: 14
Views: 275

### Re: Dots in Lewis Stucture

I would say that although the placement doesn't necessarily matter in the Lewis Structure, as a rule of thumb make sure that your placement next to the other atom is precise because that's where your bond will be and it makes it less visually confusing for grading. Fill out the other 3 sides before ...
Sun Oct 28, 2018 10:03 pm
Forum: Ionic & Covalent Bonds
Topic: Cation/Anion Size
Replies: 3
Views: 60

### Cation/Anion Size

If electrons get pulled into the nucleus when there is a higher negative charge (giving them a smaller size), why are cations smaller than anions? Wouldn't it be that with fewer electrons it would be more spaced out/larger?
Sun Oct 28, 2018 9:56 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures with Charges
Replies: 6
Views: 138

### Re: Drawing Lewis Structures with Charges

Can Lewis structures be used to construct the molecular structure of the element? So Lewis Structures tell you the valence electron # of the atoms, so it can help tell you the position the atom has in a molecule. So because molecular structures are dependent on the spatial orientation of covalent b...
Sun Oct 14, 2018 11:31 pm
Forum: Student Social/Study Group
Topic: Note Taking
Replies: 32
Views: 1515

### Re: Note Taking

For me, the best way to take notes is to write down the powerpoint and insert different extra notes he says in class. After class though, I find it really helpful to watch his video module (which is a lecture with roughly the same powerpoint) as a refresher and take any notes I missed while writing ...
Sun Oct 14, 2018 11:26 pm
Forum: DeBroglie Equation
Topic: Angstrom?
Replies: 8
Views: 182

### Re: Angstrom?

You'll commonly see it written as Å in this class for exams, etc, and it is used to measure the size of atoms/molecules, the length of chemical bonds, or the wavelengths of electrochem radiation. It is equivalent to 1.0 × 10-10 meters, but its not an SI unit. For example, hydrogen is about 0.5 Å, wh...
Sun Oct 14, 2018 11:20 pm
Forum: DeBroglie Equation
Topic: Post-Assessment Question 34
Replies: 1
Views: 45

### Post-Assessment Question 34

Can someone explain this answer? Particularly the last portion.

34. If an electron (mass 9.11 x 10-31 kg) has an associated wavelength of 7.28 x 10-9 m, what is its speed? Is your answer reasonable, why?
Sun Oct 07, 2018 10:38 pm
Forum: Limiting Reactant Calculations
Topic: Theoretical vs Actual Yield
Replies: 5
Views: 323

### Theoretical vs Actual Yield

Why is theoretical yield greater than actual yield in chemical reactions?
Sun Oct 07, 2018 10:35 pm
Forum: Empirical & Molecular Formulas
Topic: HW F11
Replies: 4
Views: 130

### Re: HW F11

I think the professor said that we don't need to know polyatomic ions as of right now, and not for the first test. We may go further in depth about them later in class, though.
Sun Oct 07, 2018 10:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Number of questions on test one [ENDORSED]
Replies: 39
Views: 17554

### Re: Number of questions on test one[ENDORSED]

I think that it will probably be 8 questions like stated above with one for each topic of the review (empirical formula, molecular formula, balancing chemical equations, limiting reactant calculations, and molarity/ dilution of a solution).
Sun Oct 07, 2018 10:24 pm
Forum: Limiting Reactant Calculations
Topic: different ways to determine limiting reactant
Replies: 3
Views: 54

### Re: different ways to determine limiting reactant

I think that if you can try and do it the way it was taught in class it would be beneficial since we will be graded on partial credit so the steps might be an important factor.