Search found 54 matches

by Alexa Mugol 3I
Sat Dec 07, 2019 12:31 am
Forum: Naming
Topic: Parentheses in naming
Replies: 1
Views: 27

Parentheses in naming

In 9C.3, one of the compounds is sodium bisoxalato(diaqua)ferrate(III). Why is diaqua in parentheses?
In 9C.4, there's another compound called barium tris(oxalato)ferrate(III). Why is oxalato in parentheses here but not in the other one?
Are there other times when you use parentheses in naming?
by Alexa Mugol 3I
Tue Dec 03, 2019 10:04 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Question 9C.5
Replies: 1
Views: 34

Re: Question 9C.5

You would draw the Lewis structure and see how many atoms in the molecule have a lone pair/lone pairs. For example, HN(CH2CH2NH2)2 has three nitrogens each with lone pairs. Therefore, there are three sites for bonding and the molecule is tridentate. Water only has one oxygen atom with lone pairs, so...
by Alexa Mugol 3I
Tue Dec 03, 2019 9:58 pm
Forum: Bronsted Acids & Bases
Topic: J.7
Replies: 1
Views: 30

Re: J.7

I don't think it matters what order you write the reactants/products in the chemical equation. And 3KOH would be correct because K3(OH)3 would imply that it's a different molecule.
by Alexa Mugol 3I
Tue Dec 03, 2019 9:51 pm
Forum: Lewis Structures
Topic: Ozone lewis structure
Replies: 3
Views: 54

Re: Ozone lewis structure

If it had two double bonds, then it would violate the octet rule on oxygen since it is 2p and does not have any d orbitals to expand its valence shell. Also keep in mind that the Lewis structure is not an accurate representation since the actual ozone structure exhibits resonance.
by Alexa Mugol 3I
Tue Dec 03, 2019 9:49 pm
Forum: Coordinate Covalent Bonds
Topic: chelating ligands
Replies: 1
Views: 43

Re: chelating ligands

Image
The metal would bind to each N on the diethylenetriammine.
by Alexa Mugol 3I
Tue Dec 03, 2019 9:46 pm
Forum: Naming
Topic: Polydentate
Replies: 2
Views: 35

Re: Polydentate

A polydentate will have multiple sites where the central metal can bond to. Common examples are ethylenediamine, oxalate, diethylenetriamine, and EDTA. https://chem.libretexts.org/@api/deki/files/71147/Ethylenediamine.jpg?revision=1&size=bestfit&width=213&height=126 As you can see, ethyl...
by Alexa Mugol 3I
Tue Dec 03, 2019 9:38 pm
Forum: Bronsted Acids & Bases
Topic: How to determine whether a molecule is an acid or a base
Replies: 5
Views: 43

Re: How to determine whether a molecule is an acid or a base

Generally, molecules with lone pairs are more likely to donate that electron pair, which is the Lewis definition of a base. Therefore, molecules with more lone pairs are more likely to be bases since they have more electrons to donate.
by Alexa Mugol 3I
Sun Dec 01, 2019 1:57 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination compounds
Replies: 1
Views: 29

Re: Coordination compounds

Yes, on outline 5, it says we need to know how to "Identify the shape and draw structures of coordination compounds."
Here's the link: https://lavelle.chem.ucla.edu/wp-conten ... rtance.pdf
by Alexa Mugol 3I
Tue Nov 26, 2019 2:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 9C.3
Replies: 4
Views: 48

Re: 9C.3

Claire Lo 3C wrote:Since there is a space between potassium and hexacyanidochromate (III), it indicates that potassium is out of the bracket.

K3 [Cr(CN)6]

How do you know it's K3 and not just K? Is it to neutralize the overall charge of the compound?
by Alexa Mugol 3I
Tue Nov 26, 2019 2:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Sphere
Replies: 5
Views: 33

Re: Coordination Sphere

Why is six the maximum coordination number? (I vaguely remember this from lecture but I’m not sure whether it’s accurate. Is it some simple rule of geometry that dictates it, or is there something I’m missing here? Six is the maximum coordination number because atoms can bond only up to six times (...
by Alexa Mugol 3I
Tue Nov 26, 2019 2:27 pm
Forum: Naming
Topic: Naming
Replies: 3
Views: 35

Re: Naming

(Greek prefix) ligand names in alphabetical order, then transition metal cation name (Roman numeral of oxidation number). Greek prefix means di-, tri-, tetra-, etc. based on how many of the ligand there are.
by Alexa Mugol 3I
Tue Nov 26, 2019 2:24 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation Number vs. Coordination Number
Replies: 8
Views: 56

Re: Oxidation Number vs. Coordination Number

Oxidation number is the charge of the transition metal in the center of the coordination compound. Coordination number is the number of bonds from the central metal atom.
by Alexa Mugol 3I
Wed Nov 20, 2019 4:22 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: 3F19 Part C
Replies: 2
Views: 32

Re: 3F19 Part C

This image helped me in this question: https://d2jmvrsizmvf4x.cloudfront.net/4R0YfccRWSh91K2SdVFQ_states14.gif Since they write neopentane as C(CH 3 ) 4 , you would put a C in the center and bond it to four other Cs. So in a way, the textbook tries to help you out with the structure by writing the f...
by Alexa Mugol 3I
Wed Nov 20, 2019 4:13 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: 3F.19
Replies: 5
Views: 54

Re: 3F.19

Anisha Chandra 4H wrote:Just to clarify, does high vapor pressure indicate higher boiling point?

The stronger the intermolecular forces, the lower the vapor pressure and the higher the boiling point :)
by Alexa Mugol 3I
Tue Nov 19, 2019 9:55 pm
Forum: Sigma & Pi Bonds
Topic: Resonance Structures in 2F.3
Replies: 4
Views: 33

Re: Resonance Structures in 2F.3

Hello Alexa Mugol 3I! To answer your question, which resonance structure are you referring to? The lewis structure for SO2 would be S as central atom with a single bond between S and one of the Oxygens and a double bond between the S and the other Oxygen atom with a lone pair of electrons on the S ...
by Alexa Mugol 3I
Tue Nov 19, 2019 9:50 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: 3F.19
Replies: 5
Views: 54

3F.19

In 3F.19 b), it says that H bonding in water causes the molecules to be held together more tightly than in diethyl ether. But if there are two lone pairs on the central O atom, then doesn't diethyl ether have H bonding too? What makes the H bonding in water stronger than the H bonding in diethyl eth...
by Alexa Mugol 3I
Tue Nov 19, 2019 9:01 pm
Forum: Sigma & Pi Bonds
Topic: Resonance Structures in 2F.3
Replies: 4
Views: 33

Resonance Structures in 2F.3

For 2F.3, it says that SO2 would have 2 sigma bonds and 1 pi bond, but there is also a resonance structure that has 2 sigma bonds and 2 pi bonds. Would either answer for either resonance structure be correct?
by Alexa Mugol 3I
Tue Nov 19, 2019 7:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Why T-shape?
Replies: 4
Views: 34

Why T-shape?

Why is an AX3E2 molecule T-shaped? I thought it would be trigonal planar so that the lone pair electrons are opposite from each other. Why would the lone pair electrons be next to each other?
by Alexa Mugol 3I
Fri Nov 15, 2019 10:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Symmetry and Polarity
Replies: 13
Views: 98

Re: Symmetry and Polarity

Not really. Although asymmetrical Lewis structures are usually polar, there are many symmetrical Lewis structures that are polar too. Take water for example. It is symmetrical in its Lewis structure and its electron geometry, but it's still polar because the dipoles don't cancel out. Best to just dr...
by Alexa Mugol 3I
Fri Nov 15, 2019 10:46 pm
Forum: Dipole Moments
Topic: Xenon
Replies: 4
Views: 48

Re: Xenon

I think he mentioned something about how since xenon has a low electronegativity, its electrons are more easily distorted by atoms with stronger electronegativity, like fluorine. In addition, Xe is highly polarizable since it has so many electrons, so it will be able to bond with highly electronega...
by Alexa Mugol 3I
Fri Nov 15, 2019 10:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 6
Views: 37

Re: Bond Angles

If there are any lone pairs on the molecule, the bond angle will be slightly less because the lone pair has very strong repulsion, so it will push the surrounding atoms even more than a normal atom would. Therefore, more lone pairs --> slightly smaller bond angle.
by Alexa Mugol 3I
Fri Nov 15, 2019 10:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar vs Nonpolar Example
Replies: 3
Views: 40

Re: Polar vs Nonpolar Example

In cis-dischloroethene, the Cl atoms are on the same side, so the partial negatives are on the same side. Therefore, there's a big area with partial negative and the other side is partial positive. In trans-dischloroethene, the Cl atoms are on opposite sides of each other, so the partial negatives c...
by Alexa Mugol 3I
Fri Nov 15, 2019 10:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent molecular shapes (AX2E2)
Replies: 1
Views: 29

Re: Bent molecular shapes (AX2E2)

This is because the electron geometry (geometry including the lone pair electrons) is tetrahedral. In a tetrahedral electron geometry, all the sites of electron density are next to each other; there aren't any spots where they can be opposite each other. This differs from square planar where the lon...
by Alexa Mugol 3I
Mon Nov 11, 2019 8:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dipole moment
Replies: 4
Views: 43

Re: Dipole moment

sarahsalama1G wrote:So when an atom is not bonded to itself, does that always result in a dipole moment?

In a bond between two different atoms, there would be a dipole moment. But in a whole molecule, such as CH4, the dipole moments cancel out and the molecule itself is nonpolar.
by Alexa Mugol 3I
Mon Nov 11, 2019 8:41 pm
Forum: Dipole Moments
Topic: Dipole moments
Replies: 2
Views: 22

Re: Dipole moments

Dispersion forces are pretty much instantaneous dipole moments that occur in all atoms and molecules, nonpolar and polar. So nonpolar molecules do experience dipole moments but only for an instant.
by Alexa Mugol 3I
Mon Nov 11, 2019 8:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Model
Replies: 3
Views: 31

Re: VSEPR Model

I don't think so unless you have an idea of what the Lewis structure looks like in your head (like the structure of a bent water molecule). Drawing the structure is helpful in visualizing where the atoms and lone pair electrons are located so you can see how they might repel or best be arranged.
by Alexa Mugol 3I
Mon Nov 11, 2019 8:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Hydrogen Bonding
Replies: 3
Views: 27

Re: Hydrogen Bonding

Hydrogen bonding is a very strong intermolecular force, so the forces between the molecules are much stronger compared to other forces like dipole-dipole or dispersion forces. Melting point is increasing the energy of the atoms so that they go from solid to liquid, and if the attractive forces are s...
by Alexa Mugol 3I
Mon Nov 11, 2019 8:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 3
Views: 36

Re: Molecular Shape

The shape can contribute to the strength of an interaction because more surface area interacting to make the bond will lead to a stronger bond. By shape, we mean the shape of the molecule--because electrons repel each other, a certain arrangement of atoms will minimize the repulsions and thus maximi...
by Alexa Mugol 3I
Fri Nov 01, 2019 11:38 am
Forum: Photoelectric Effect
Topic: Threshold Energy
Replies: 2
Views: 38

Re: Threshold Energy

Threshold energy is the minimum amount of energy to eject an e- (from the photoelectric effect). If the incoming light has more than the threshold energy, the remaining energy is emitted as kinetic energy. Therefore, E(incoming light) = threshold energy + kinetic energy. Usually, the work function i...
by Alexa Mugol 3I
Fri Nov 01, 2019 11:34 am
Forum: DeBroglie Equation
Topic: Converting mass to kilograms for de broglie
Replies: 7
Views: 38

Re: Converting mass to kilograms for de broglie

That is correct. Since it's asking you for the wavelength of a single atom, you'd have to find the mass in kg of a single atom. It's also a good idea to make sure your units cancel out in your calculations and you're left with the units that you want.
by Alexa Mugol 3I
Fri Nov 01, 2019 11:29 am
Forum: Octet Exceptions
Topic: Octet Rule Exceptions
Replies: 4
Views: 41

Re: Octet Rule Exceptions

Elements in n=3 or higher can expand their valence shell because it has open d orbitals. So pretty much, an easy way to tell if there's an octet rule exception is if there are open d orbitals in a given atom. n=2 elements cannot expand their valence shell because n=2 does not have any d orbitals. n=...
by Alexa Mugol 3I
Fri Nov 01, 2019 11:21 am
Forum: Lewis Structures
Topic: Central atom
Replies: 6
Views: 34

Re: Central atom

In the lecture, I believe Dr. Lavelle put that the central atom is the one with the lowest ionization energy. A good rule of thumb is that carbon is almost always the central atom.
by Alexa Mugol 3I
Fri Nov 01, 2019 11:19 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Writing electron configuration
Replies: 7
Views: 57

Re: Writing electron configuration

3d comes before 4s because 4s is higher in energy than 3d. Therefore, you would remove 4s electrons before 3d electrons (if 4s came before 3d it would be harder to tell which is the valence).
by Alexa Mugol 3I
Fri Oct 25, 2019 11:30 am
Forum: Ionic & Covalent Bonds
Topic: Bond length
Replies: 11
Views: 82

Re: Bond length

As you saw in the resonance structures of nitrate, there are multiple places where you can place the double bond in the Lewis dot structure. Those different places for the double bond kind of exist all at the same time because the electrons are delocalized (think of delocalized electrons in metallic...
by Alexa Mugol 3I
Fri Oct 25, 2019 11:24 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sulfur bonding
Replies: 5
Views: 39

Re: Sulfur bonding

To add on to the other replies, P, Cl, and S can bond up to 6 times because they can utilize their empty 3d orbitals. 2p elements aren't able to do this because there aren't any 2d orbitals. I'm pretty sure that other elements with empty d orbitals can also bond more than 4 times.
by Alexa Mugol 3I
Fri Oct 25, 2019 11:20 am
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy
Replies: 5
Views: 48

Re: Ionization Energy

Instead of thinking about what diagonal direction each trend increases/decreases toward, think about how they change down a group and across a period. IE increases across the period to the right because increasing Z attracts the e- closer to the nucleus and removing an e- from a shell that's almost ...
by Alexa Mugol 3I
Fri Oct 25, 2019 11:15 am
Forum: Trends in The Periodic Table
Topic: types of radii
Replies: 4
Views: 49

Re: types of radii

I think we should just know the general periodic trends of atomic radii. I asked my TA if we needed to know much about covalent radii (because Dr. Lavelle didn't really go into much detail), but I don't think we need to know it in detail, just the general trends.
by Alexa Mugol 3I
Thu Oct 24, 2019 9:25 pm
Forum: DeBroglie Equation
Topic: hw problem 1B.23
Replies: 4
Views: 64

Re: hw problem 1B.23

Actually, I believe most equations use meters for wavelength. So you would convert the given wavelength, whether in nm or pm, to m when doing calculations.
by Alexa Mugol 3I
Sun Oct 20, 2019 11:02 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions to the rules
Replies: 3
Views: 40

Re: Exceptions to the rules

The electron configuration is most stable this way because it minimizes the electron-electron repulsion. Therefore, the electrons are more stable in 3d54s1 than in 3d44s2 since they're all unpaired.
by Alexa Mugol 3I
Thu Oct 17, 2019 11:08 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Heisenberg's Indeterminancy Equations
Replies: 2
Views: 35

Re: Heisenberg's Indeterminancy Equations

ΔpΔx >= h/4pi is the main equation we use when finding uncertainty in position/momentum. I believe the other one you're talking about is Δp=mΔv. We use this one to find Δp for the main equation. The reason why there's Δv and not Δm is because mass stays constant and there's no uncertainty to mass, t...
by Alexa Mugol 3I
Thu Oct 17, 2019 11:03 pm
Forum: Properties of Light
Topic: Homework 1B. 15
Replies: 2
Views: 27

Re: Homework 1B. 15

For a), use the DeBroglie wavelength equation (lambda/mv) using the velocity given. For b), you use E=h*(frequency), using the frequency given. Then you can use the threshold energy equation to find the work function. For c), use E k =mv 2 /2 to find the energy then use E=hc/lambda to find the wavel...
by Alexa Mugol 3I
Thu Oct 17, 2019 2:04 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Indeterminacy in Position [ENDORSED]
Replies: 5
Views: 74

Re: Indeterminacy in Position [ENDORSED]

To answer Leila's question, Δx represents the indeterminacy in position of the e-, or the possible places to find the e-. Since we suppose that the e- is possibly in the nucleus, we would use the diameter of the nucleus to represent the uncertainty in position. It would not have anything to do with ...
by Alexa Mugol 3I
Thu Oct 17, 2019 1:59 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: uncertainty in position
Replies: 4
Views: 53

Re: uncertainty in position

The problem gives you a mass of 8.00 kg and a velocity of 5.00 m.s-1. The product of these will make up the momentum (Δp), which you will plug in to solve for Δx.
by Alexa Mugol 3I
Mon Oct 14, 2019 4:49 pm
Forum: Properties of Light
Topic: Matching Wavelength to Type of EM Radiation
Replies: 2
Views: 26

Matching Wavelength to Type of EM Radiation

In problem 1B.15, we're asked to calculate the energy to remove an e-, then calculate the wavelength associated with it, and then name the kind of EM radiation used. I was able to do the first two, but I had to look back in the textbook reading to match the wavelength to the type of EM radiation. Ar...
by Alexa Mugol 3I
Fri Oct 11, 2019 11:43 pm
Forum: Properties of Electrons
Topic: Energy levels
Replies: 3
Views: 32

Re: Energy levels

I think Dr. Lavelle did that in some of the worked out examples to help us visualize what exactly is going on in the problem. I don't think it's necessary to solve the problem, but drawing it out or visualizing it in your head until you understand it will be helpful in comprehending problems the fir...
by Alexa Mugol 3I
Thu Oct 10, 2019 9:02 pm
Forum: Properties of Light
Topic: Question 1.A.3
Replies: 4
Views: 47

Re: Question 1.A.3

I was confused about this too. If you look at Figure 1A.7 in the text, it says that "the electric field of electromagnetic radiation oscillates in space and time" (referring to the oscillating waves in the radiation). So, I think when C says "extent of change in the electrical field,&...
by Alexa Mugol 3I
Thu Oct 10, 2019 8:50 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Types of E
Replies: 3
Views: 77

Re: Types of E

The E in E=hc/wavelength is the energy per photon, while the Ek in the threshold energy equation is the kinetic energy that is released when the energy of the incoming light is greater than the threshold energy.
by Alexa Mugol 3I
Thu Oct 10, 2019 8:45 pm
Forum: Properties of Light
Topic: hw problem 1.A.15
Replies: 3
Views: 74

Re: hw problem 1.A.15

The previous person explained it pretty well! I'd like to add that we know that it starts at energy level 1 (n1=1) because it's in the ultraviolet spectrum, aka the Lyman series, so it's starts at n=1.
by Alexa Mugol 3I
Thu Oct 10, 2019 8:30 pm
Forum: Molarity, Solutions, Dilutions
Topic: Module Question Help
Replies: 2
Views: 88

Re: Module Question Help

The question seemed a little confusing at first for me too, especially with the extra numbers. But basically, you first find the concentration of the the first solution (5g in 150 mL) by converting to moles and then dividing by the volume (in L). The solution has the same concentration no matter wha...
by Alexa Mugol 3I
Tue Oct 01, 2019 11:08 pm
Forum: Balancing Chemical Reactions
Topic: Tips for Balancing Chemical Equations [ENDORSED]
Replies: 14
Views: 195

Re: Tips for Balancing Chemical Equations [ENDORSED]

One thing I've picked up on is to treat polyatomic ions like their own elements when balancing an equation where polyatomic ions are present. For example, if there's one nitrate on the reactant side, and two nitrates on the product side, you can balance the equation by adding the coefficient 2 to th...
by Alexa Mugol 3I
Tue Oct 01, 2019 12:02 pm
Forum: Balancing Chemical Reactions
Topic: State Symbols in Equations
Replies: 8
Views: 100

State Symbols in Equations

In my high school chemistry classes, we never really used the state symbols, like (s), (g), (aq), when writing chemical equations. I was wondering if we should use them when writing equations in this course and if there are any benefits of using them/if they help in some way. Thanks!
by Alexa Mugol 3I
Sun Sep 29, 2019 5:10 pm
Forum: Empirical & Molecular Formulas
Topic: HW Question L.39 - What in the world is a crucible you guys?
Replies: 3
Views: 52

Re: HW Question L.39 - What in the world is a crucible you guys?

A crucible is a container that you can heat to high temperatures. https://www.preciseceramic.com/wp-content/uploads/2019/07/lab-crucibles.jpg In this question, tin was put into a crucible and heated so it can react with oxygen to make a tin oxide. The problem gives you the mass of the crucible and t...
by Alexa Mugol 3I
Sat Sep 28, 2019 9:58 pm
Forum: SI Units, Unit Conversions
Topic: Nomenclature
Replies: 4
Views: 138

Re: Nomenclature

Additionally, if there is an ionic compound with a polyatomic ion in it, you would have to use the name of the polyatomic ion (it's usually the anion). For example: NaOH = sodium hydroxide, CaCO 3 = calcium carbonate, Cu(NO 3 ) 2 = copper(II) nitrate, (NH 4 ) 2 S = ammonium sulfide Hope this helped :)
by Alexa Mugol 3I
Sat Sep 28, 2019 9:47 pm
Forum: Empirical & Molecular Formulas
Topic: HW Problem F15
Replies: 2
Views: 59

Re: HW Problem F15

Hi! I just looked it up, and apparently there's this thing called the Hill System Order that explains what order you write each element: 1. Carbon 2. Hydrogen 3. The rest in alphabetical order. Pretty much, you always put C and H first (in that order) and then the rest alphabetically. Here's the lin...

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