Search found 30 matches

by nicolesalcedo
Tue Jun 12, 2018 12:52 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 788992

Re: Post All Chemistry Jokes Here

The optimist sees the glass half full. The pessimist sees the glass half empty. The chemist sees the glass completely full, half with liquid and half with air.
by nicolesalcedo
Tue Jun 12, 2018 12:48 pm
Forum: General Science Questions
Topic: Bond angles
Replies: 4
Views: 287

Re: Bond angles

The VSEPR formula really helps with determining the shape and bond angles!
by nicolesalcedo
Sat Jun 02, 2018 4:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: regions of e- density
Replies: 4
Views: 93

Re: regions of e- density

in addition, multiple bonds are treated as equal to single bonds; i.e. a double bond does not have more repulsion than a single bond.
by nicolesalcedo
Sat Jun 02, 2018 4:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 7
Views: 176

Re: Bond Angles

It would also be helpful to consider the repulsion between lone pairs and bonds. With the Lewis structure and the shape known, you can use lone-lone > lone-bond > bond-bond to help with determining bond angle.
by nicolesalcedo
Sat Jun 02, 2018 4:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 2
Views: 66

Re: Lone Pairs

To add on, the lone pairs will push away from the bonds stronger, making bond angles smaller. Thus, looking at the VSEPR formula is extremely helpful when determining shape. For example, AX3 will yield trigonal planar with bond angles 109.5 but AX3E will yield trigonal pyramidal with bond angles <10...
by nicolesalcedo
Sun May 27, 2018 12:17 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 788992

Re: Post All Chemistry Jokes Here

*texting a chemistry major*

"Hey you wanna go to the movies rn?"

"Sure, when?"

"Rn"

"What do you mean by Radon?"

"..."
by nicolesalcedo
Sun May 27, 2018 12:02 pm
Forum: Ionic & Covalent Bonds
Topic: Group 17
Replies: 2
Views: 72

Re: Group 17

To expand, the elements under Flourine in group 17 are all exceptions to the octet rule.
by nicolesalcedo
Sun May 27, 2018 11:56 am
Forum: Electronegativity
Topic: Calculating electronegativity
Replies: 10
Views: 318

Re: Calculating electronegativity

When comparing electronegativity between elements, you can assume that the element that has more valence electrons or a fuller outer shell is more electronegative.
by nicolesalcedo
Sun May 20, 2018 2:53 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 7
Views: 184

Re: Polarizability

Yes, exactly :)
by nicolesalcedo
Sun May 20, 2018 2:50 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 7
Views: 184

Re: Polarizability

Anions are opposite from anions; polarizability increases as ions get larger and less electronegative.
by nicolesalcedo
Sun May 20, 2018 2:49 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 7
Views: 184

Re: Polarizability

Smaller, more highly-charged cations have greater polarization power. In terms of ionic radius, polarization increases from big to small atoms. You can refer to question 3.81.
by nicolesalcedo
Sun May 20, 2018 2:47 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 7
Views: 184

Re: Polarizability

Generally, larger molecules are more polarizable than smaller molecules.
by nicolesalcedo
Tue May 15, 2018 11:24 pm
Forum: Lewis Structures
Topic: Identifying elements in Lewis structures [ENDORSED]
Replies: 2
Views: 95

Re: Identifying elements in Lewis structures [ENDORSED]

Lavelle hasn't gone over this so I'm not 100% certain, but I would use the charges of the known elements in the lewis structure, count the number of shared electrons/bonds the central element has, and count the total number of electrons the lewis structure contains. I think all of these would help s...
by nicolesalcedo
Tue May 15, 2018 11:12 pm
Forum: Ionic & Covalent Bonds
Topic: Name to Bond [ENDORSED]
Replies: 1
Views: 72

Re: Name to Bond [ENDORSED]

I think the numbers represent the charge of the element. For example, CuO can be written as Copper(II) oxide to describe that copper has a +2 charge. Since O has a -2 charge, the overall charge is 0. For thallium III chloride: Tl has a +3 charge and Cl has a -1 charge, so you need 3 Cl to make the c...
by nicolesalcedo
Tue May 15, 2018 11:02 pm
Forum: Lewis Structures
Topic: Which atom to have the charge in lewis structures
Replies: 2
Views: 70

Re: Which atom to have the charge in lewis structures

I believe that the charge should be on whatever atom has the extra/remaining (whether it be positive or negative) charge. For example, during lecture on Friday, one of the TA's wrote the lewis structure of SO4-2 with 4 single bonds (all the O's had -1 charge and the S had a +2 charge). After rewriti...
by nicolesalcedo
Sun May 06, 2018 1:24 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Unpaired Electrons from Electron Configurations [ENDORSED]
Replies: 2
Views: 77

Unpaired Electrons from Electron Configurations [ENDORSED]

How do you determine the number of unpaired electrons if you are given the electron configuration of an element?
by nicolesalcedo
Sun May 06, 2018 1:14 pm
Forum: Trends in The Periodic Table
Topic: Isoelectric Atomic Radii
Replies: 3
Views: 83

Re: Isoelectric Atomic Radii

Just to elaborate on the trend, atomic radii increases as you go down and to the left of the periodic table. For example, look at homework #2.59
by nicolesalcedo
Sun Apr 29, 2018 2:11 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electrons in an Orbital [ENDORSED]
Replies: 8
Views: 157

Re: Electrons in an Orbital [ENDORSED]

For instance, in the carbon example that Lavelle gave us in class, why are the two electrons in two different orbitals even though they are in the same subshell? Is it just because they have the same spin?
by nicolesalcedo
Sun Apr 29, 2018 2:01 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electrons in an Orbital [ENDORSED]
Replies: 8
Views: 157

Re: Electrons in an Orbital [ENDORSED]

And just to confirm, those two electrons need to have opposite spins, otherwise they cannot be together?
by nicolesalcedo
Sun Apr 29, 2018 1:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electrons in an Orbital [ENDORSED]
Replies: 8
Views: 157

Electrons in an Orbital [ENDORSED]

Hi, I wasn't able to come to lecture on Friday, so I'm unsure about the number of electrons in a orbital. I've seen models where there are up to 8 electrons in an orbital, is the maximum really just two?
by nicolesalcedo
Sun Apr 22, 2018 6:50 pm
Forum: Photoelectric Effect
Topic: Wave vs. Particle
Replies: 8
Views: 141

Re: Wave vs. Particle

sorry, correction: the wave model is on wavelength and frequency* (not amplitude)
by nicolesalcedo
Sun Apr 22, 2018 1:04 pm
Forum: Photoelectric Effect
Topic: Wave vs. Particle
Replies: 8
Views: 141

Re: Wave vs. Particle

Yes, exactly :)
by nicolesalcedo
Sun Apr 22, 2018 1:01 pm
Forum: Photoelectric Effect
Topic: Wave vs. Particle
Replies: 8
Views: 141

Re: Wave vs. Particle

If you increase the intensity of the wave, it just increases the number of photons that are being directed at the piece of metal, thus increasing the number of electrons being ejected (1:1 photon electron ratio). However, if the wavelength (aka the energy of the photon) is not enough to eject an ele...
by nicolesalcedo
Sun Apr 22, 2018 12:56 pm
Forum: Photoelectric Effect
Topic: Wave vs. Particle
Replies: 8
Views: 141

Re: Wave vs. Particle

The wave model for light is in regards to wavelength and amplitude (aka intensity). When you look at the light model in regards to particles, you look at the photon energies of the light.
by nicolesalcedo
Wed Apr 11, 2018 11:05 am
Forum: Molarity, Solutions, Dilutions
Topic: STEPS to figuring out solutions/ molarity quesitons
Replies: 2
Views: 90

Re: STEPS to figuring out solutions/ molarity quesitons

Mainly, I think the main topics would be find the molarity, find the concentration of ions, molecules, etc.
by nicolesalcedo
Wed Apr 11, 2018 10:51 am
Forum: Properties of Light
Topic: Value of Speed of Light** (Shoutout to Dr. Lavelle for calling me out in lecture today) [ENDORSED]
Replies: 4
Views: 155

Re: Value of Speed of Life [ENDORSED]

I think it's preferred to use the scientific notation for the speed of light when making calculations. It's 3.00*10^8m/s
by nicolesalcedo
Wed Apr 11, 2018 10:46 am
Forum: SI Units, Unit Conversions
Topic: Formula Units
Replies: 5
Views: 119

Re: Formula Units

So for covalent bonds, you would answer with something like 6.022*10^23 molecules, and then for ionic bonds, you would answer with 6.022*10^23 formula units?
by nicolesalcedo
Wed Apr 11, 2018 10:41 am
Forum: SI Units, Unit Conversions
Topic: Formula Units
Replies: 5
Views: 119

Re: Formula Units

So in e21, it says to calculate moles and the number of molecules and formula units/atoms in a) 10.0 g of alumina Al2O3. I know how to convert that to moles, since you just divide by the molar mass of alumina, and for the number of molecules, you multiply the number of moles by Avogadro's number. Bu...
by nicolesalcedo
Wed Apr 11, 2018 10:32 am
Forum: SI Units, Unit Conversions
Topic: Formula Units
Replies: 5
Views: 119

Formula Units

In practice problem E25, it asks about the number of formula units in 0.750 mol KNO3. What are formula units?
by nicolesalcedo
Wed Apr 11, 2018 10:28 am
Forum: SI Units, Unit Conversions
Topic: Length Units
Replies: 15
Views: 420

Re: Length Units

Yeah, I think that we do automatically infer that we answer in SI units since he went over SI units in lecture and since they apply to scientific notation.

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