## Search found 53 matches

Sat Dec 07, 2019 10:49 pm
Forum: DeBroglie Equation
Topic: Identifying the need to use DeBroglie Equation
Replies: 3
Views: 146

### Re: Identifying the need to use DeBroglie Equation

Any mention of something that has a mass (electrons, protons, neutrons, etc) will use DeBroglie's Equation, while any light/photons will NOT, because they do not have mass.
Sat Dec 07, 2019 1:42 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: KA1>KA2>KA3
Replies: 2
Views: 45

### Re: KA1>KA2>KA3

What pulls the H+ from molecules is a negatively charged species. Once the original molecule is negatively charged, it will repel other molecules or atoms that are negatively charged.
Sat Dec 07, 2019 1:39 pm
Forum: Bronsted Acids & Bases
Topic: Naming Acids and Bases
Replies: 1
Views: 33

### Re: Naming Acids and Bases

Since both of these are strong acids, these are two you should probably know. I would say the ones you should definitely know the names of are the strong acids and bases.
Fri Dec 06, 2019 1:54 pm
Forum: Lewis Structures
Topic: Cl as a central atom
Replies: 5
Views: 284

### Re: Cl as a central atom

In class today, Lavelle went over an example where Cl is the central atom with 6 bonds and one lone pair, so I think as long as the formal charge is 0 it is okay.
Thu Dec 05, 2019 8:11 pm
Forum: General Science Questions
Topic: Tightly bound
Replies: 2
Views: 204

### Re: Tightly bound

Bond strength can help determine which atoms are more tightly bound. More bonds between atoms (eg. triple vs double) means that the atoms will be more tightly bonded. In addition, large electronegativity difference can also generate a stronger bond.
Wed Dec 04, 2019 8:55 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: K constant and pK value
Replies: 3
Views: 41

### Re: K constant and pK value

Anika Chakrabarti 3K wrote:I'm pretty sure we aren't going to do actual calculations with Ka until 14B. What does Kw represent, though? I don't remember learning that

Kw represents the constant for H20. Kw=[H+][OH-]=1.0x10^-14
Sun Dec 01, 2019 9:06 pm
Forum: Identifying Acidic & Basic Salts
Topic: Classifying Salts
Replies: 5
Views: 57

### Classifying Salts

When you're given a salt (ex: BaCl) in water, how can you tell if it will act as an acid or base in solution?
Sun Dec 01, 2019 8:10 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 4
Views: 82

### Re: Ligands

This means that there is a complex containing a ligand that forms a ring of atoms including the central metal atom. In other words, more than one bond is formed between the metal ion and the ligand.
Sun Dec 01, 2019 7:59 pm
Forum: Amphoteric Compounds
Topic: Amphoteric Compound
Replies: 5
Views: 61

### Re: Amphoteric Compound

An amphoteric compound is one that can react as either an acid or a base. A lot of metals (like copper, zinc, tin, aluminum, etc) can form amphoteric oxides or hydroxides.
Sun Dec 01, 2019 7:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma Bond
Replies: 10
Views: 150

### Re: Sigma Bond

Yes single bonds are always sigma bonds
Sun Dec 01, 2019 6:06 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: H2SO4
Replies: 2
Views: 41

### Re: H2SO4

I believe both occur depending on the situation. When H2SO4 dissociates in water, it can form a mixture of HSO4- and SO42- molecules. This happens because after the first hydrogen is taken off, the reaction is slightly different for the second.
Sun Nov 24, 2019 4:03 pm
Forum: Biological Examples
Topic: Transition metals and their biological importance
Replies: 2
Views: 33

### Re: Transition metals and their biological importance

The ones I have that he mentioned were Chromium (which assists insulin in control of blood sugar), Iron (myoglobin, hemoglobin, electron transfer in the oxidation of carbohydrates, proteins, fats (respiratory chain), Cobalt (vitamin B12), and Manganese, Nickel, Copper, and Zinc (critical for enzyme ...
Sun Nov 24, 2019 4:01 pm
Forum: Hybridization
Topic: Hybrid orbitals
Replies: 5
Views: 56

### Re: Hybrid orbitals

I believe you use the Lewis Structure to determine the Hybrid orbitals
Sun Nov 24, 2019 3:43 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Bronsted vs. Lewis Acids and Bases
Replies: 4
Views: 77

### Re: Bronsted vs. Lewis Acids and Bases

Bronsted Acids are said to be able to donate a Hydrogen cation, while Lewis Acids are said to accept an electron pair.
Sun Nov 24, 2019 3:31 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: How to draw dipoles
Replies: 7
Views: 125

### Re: How to draw dipoles

Dipoles point towards the more electronegative atom in the molecule
Mon Nov 18, 2019 2:44 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: Dipole-Induced Dipole
Replies: 2
Views: 35

### Dipole-Induced Dipole

It says that the three types of intermolecular forces are: London Dispersion, Dipole-Dipole, and Hydrogen bonds. Where does dipole-induced dipole fall within these three categories? Or is it not in any of them?
Sun Nov 17, 2019 4:43 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 in Molecules or Between Molecules
Replies: 3
Views: 54

### Re: Intermolecular Forces in Molecules or Between Molecules

Intermolecular forces are just talking about between molecules. The bonds within molecules are intramolecular forces.
Sun Nov 17, 2019 2:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Question 2E.11) d
Replies: 1
Views: 27

### Re: Question 2E.11) d

If you check the formal charges, all are 0 when you use double bonds, so it is much more stable for the molecule to use double bonds instead of single bonds.
Sun Nov 17, 2019 2:01 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles in 2E.7
Replies: 1
Views: 24

### Re: Bond Angles in 2E.7

Lavelle mentioned in class that single, double, and triple bonds are considered single regions of electron density in VSEPR model, so the double bond wouldn't cause a greater repulsion in this model.
Sun Nov 17, 2019 12:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.25
Replies: 2
Views: 35

### Re: 2E.25

Lone pairs cause molecules to be polar because they have a strong negative presence and are usually not cancelled out by a symmetric pull in the other direction.
Sat Nov 16, 2019 4:49 pm
Forum: Dipole Moments
Topic: Shape of Molecule/Strength of Interactions
Replies: 4
Views: 57

### Re: Shape of Molecule/Strength of Interactions

Rod shaped molecules have a greater surface area and can get closer to each other than spherical molecules, which means that their attraction can be greater.
Sat Nov 16, 2019 4:32 pm
Forum: Ionic & Covalent Bonds
Topic: Character of Bonds
Replies: 7
Views: 99

### Re: Character of Bonds

yes, if the difference in electronegativity is less than 1.5 then it is covalent, and if the difference is greater then 2 it is ionic.
Sun Nov 10, 2019 6:37 pm
Forum: Dipole Moments
Topic: Boiling Point
Replies: 11
Views: 142

### Re: Boiling Point

How can we determine between elements which will have a higher boiling point? Based on the type of intermolecular forces (so london dispersion and or hydrogen bonding) you can tell which will have higher boiling points. The more attracted molecules are to each other, the higher the boiling point wi...
Sun Nov 10, 2019 6:33 pm
Forum: Dipole Moments
Topic: Electronegativity
Replies: 3
Views: 37

### Re: Electronegativity

Dipole-dipole attractions arise from differences in electronegativity
Sun Nov 10, 2019 4:29 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 3
Views: 49

### Re: Resonance Structures

There are very few exceptions to the octet rule (in terms of it not being completed). Boron and Aluminum are the two that most often don't complete an octet (having 6 valence electrons instead of 8)
Sun Nov 10, 2019 4:06 pm
Forum: Lewis Structures
Topic: Electronegative
Replies: 14
Views: 163

### Re: Electronegative

Yes electronegativity have to do with how much an atom wants the electron (more electronegative means they are close to being in a stable configuration)
Tue Nov 05, 2019 9:11 pm
Forum: Quantum Numbers and The H-Atom
Topic: Magnetic quantum number (m sub l)
Replies: 1
Views: 59

### Re: Magnetic quantum number (m sub l)

When you get to the d orbital and l values of 2 and -2, they correspond to multiple planes, not x, y, and z. So for example 3dxy, 3dyz., etc.
Sun Nov 03, 2019 3:06 pm
Forum: Octet Exceptions
Topic: Expanded Orbitals Explain Pls
Replies: 1
Views: 46

### Re: Expanded Orbitals Explain Pls

3p elements have a 3d orbital technically, but it isn't used because there isn't a need. However, if more electrons need to be accommodated (for formal charge reasons), the 3d orbital can be accessed. The 3d orbital has the ability to hold 10 electrons which is where the expanded octet electrons are...
Sun Nov 03, 2019 3:01 pm
Forum: Octet Exceptions
Topic: Max Expanded Octets
Replies: 2
Views: 54

### Re: Max Expanded Octets

Technically, yes, but in reality it more has to do with the formal charge. Whatever makes it the lowest is how many the octet should be expanded to.
Sun Nov 03, 2019 2:21 pm
Forum: Lewis Structures
Topic: Lewis structure
Replies: 3
Views: 49

### Re: Lewis structure

This would be an expanded valence which is okay if its one of the exceptions (possibility of a 3d orbital). The most common ones are Sulfur, Phosphorus, and Chlorine.
Sun Nov 03, 2019 2:08 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron configuration
Replies: 4
Views: 71

### Re: electron configuration

You remove electrons from the 4s before the 3d. Even though you fill 4s before 3d, the energy of the 3d orbital drops once electrons have been added. Whatever is written last in the electron configuration is where you take the electrons off of (for anything but exceptions)
Sun Nov 03, 2019 2:04 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron configuration
Replies: 2
Views: 44

### Re: electron configuration

4s has lower energy than 3d, but once an electron is put in 3d then its energy lowers which is why you write 3d before 4s in the electron configuration.
Sun Oct 27, 2019 5:05 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions to Electron Configuration
Replies: 7
Views: 114

### Exceptions to Electron Configuration

Are electron configurations for ions that are in the same isoelectronic series as Cu and Cr also exceptions to the normal (filling up 3d before 4s)?
Sun Oct 27, 2019 4:18 pm
Forum: Bond Lengths & Energies
Topic: C-C bond lengths
Replies: 4
Views: 58

### Re: C-C bond lengths

For the specific molecule, the bond length between two carbons is different because it is a resonance structure and the electrons are delocalized. This means that the single and double bonds between carbons or other atoms in a resonating molecule will not be two distinct values, but more of an avera...
Sun Oct 27, 2019 4:15 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: The exceptions
Replies: 2
Views: 34

### Re: The exceptions

For both Chromium and Copper, the 3d orbital is the last to be filled up with electrons (even though 4s is written after in the electron configuration). Despite this, it is more stable to have a half full or completely full 3d orbital with only a half full 4s orbital. Because of this, the 4s shell f...
Sun Oct 27, 2019 4:09 pm
Forum: Lewis Structures
Topic: Dots vs Lines in Lewis Structures
Replies: 6
Views: 85

### Re: Dots vs Lines in Lewis Structures

I don't think it really matters, but I think Lavelle said it was best to use lines to represent bonds because it is more obvious/symbolic.
Sun Oct 27, 2019 3:57 pm
Forum: Resonance Structures
Topic: Determining Resonance
Replies: 3
Views: 50

### Re: Determining Resonance

By determining the formal charges on each of the atoms in each variation you can see if one is more stable than others (0 is the most stable).
Tue Oct 22, 2019 2:36 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy for the 2nd Electron
Replies: 3
Views: 27

### Ionization Energy for the 2nd Electron

In class we talked about how the 2nd electron is always harder to remove (ionization energy for the 2nd electron is always higher than for the 1st electron), but I was wondering if this includes atoms like Mg and Ca, in group 2. Since taking off the 2nd electron would give them a full octet of valen...
Sun Oct 20, 2019 5:39 pm
Forum: DeBroglie Equation
Topic: Wave properties module
Replies: 2
Views: 64

### Re: Wave properties module

Yes you would. If you multiply the km/hr by 1000 (or 1000m/1km) and by 3600 (60sec*60min/1 hour) it will come out to m/sec
Sun Oct 20, 2019 5:29 pm
Forum: General Science Questions
Topic: TEST 1
Replies: 3
Views: 70

### Re: TEST 1

Celena Kim 3I wrote:Do you know if in future tests, we will also be provided with a formula sheet?

Yes, the formula sheet will be provided for all of the tests I believe.
Sun Oct 20, 2019 3:37 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty value
Replies: 4
Views: 50

### Re: Uncertainty value

I believe it would be +/- 5mm
Sun Oct 20, 2019 12:44 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: complementarity in the uncertainty principle
Replies: 1
Views: 48

### Re: complementarity in the uncertainty principle

Because the indeterminacy equation states that the product of the indeterminacy of momentum and the indeterminacy in position of an electron is equal to or greater than a constant value, it is impossible to have small values of indeterminacy for both the momentum and the position. Just like in the e...
Sun Oct 20, 2019 12:16 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions for Electron Configuration
Replies: 6
Views: 59

### Re: Exceptions for Electron Configuration

The norm is that the 4s orbital would fill up before the 3d orbital, so each element would have 4s^2 before 3d. However, in both Cu and Cr, the 4s orbital is not full, while the 3d orbital is partially full or completely full (3d^5 or 3d^10) for the purposes of stability. This is why they are called...
Sun Oct 13, 2019 4:42 pm
Forum: Properties of Light
Topic: Quanta
Replies: 4
Views: 76

### Re: Quanta

I don't think quanta have units, but rather act like moles which can be used to describe the amount of something (in this case energy).
Sun Oct 13, 2019 3:00 pm
Forum: Einstein Equation
Topic: Equations and their purpose
Replies: 3
Views: 73

### Equations and their purpose

I am a little confused on all of the equations in the unit so far. What are the classifications of each equation (like when you can use what)?
Sun Oct 13, 2019 2:54 pm
Forum: Student Social/Study Group
Topic: Turning in Extra HW problems
Replies: 10
Views: 216

### Re: Turning in Extra HW problems

Is it effective to do the whole homework list? Or should I focus on doing a few problems from each section? I find that it is most efficient for me to read through all the problems and focus on the ones I am not sure how to do or that I want more review on. I skip some that I feel I can in my head ...
Sun Oct 13, 2019 11:44 am
Forum: Quantum Numbers and The H-Atom
Topic: Circular Standing Waves and "in phase"
Replies: 2
Views: 68

### Circular Standing Waves and "in phase"

In class, when describing the circular standing waves around the nucleus in an atom, the phrase "in phase" was used. What does this mean in regards to energy levels?
Sun Oct 13, 2019 11:01 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation
Replies: 3
Views: 40

### Re: Rydberg Equation

The Rydberg Equation is used to predict the wavelength of light from an electron moving between energy levels of an atom.
Wed Oct 02, 2019 7:50 pm
Forum: SI Units, Unit Conversions
Topic: Sig figs
Replies: 18
Views: 339

### Re: Sig figs

No, you should be answering each individual question with the number of sig figs in the question (depending on addition or multiplication it could be different). There isn't a general set number of sig figs for the homework.
Wed Oct 02, 2019 6:05 pm
Forum: Balancing Chemical Reactions
Topic: H13 Is there a good step by step way to balance this?
Replies: 4
Views: 62

### Re: H13 Is there a good step by step way to balance this?

For this equation I started by putting a 2 in front of NO so there are 4 oxygens on the left and two nitrogens. Then, I put a 2 in front of the NO2 which makes 2 nitrogens and 4 oxygens on the right which should be balanced.
Wed Oct 02, 2019 5:44 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Question
Replies: 4
Views: 44

### Re: Limiting Reactant Question

They would not be considered limiting reactants because neither is limiting the other in regards to the production of the product.
Wed Oct 02, 2019 2:40 pm
Forum: Limiting Reactant Calculations
Topic: M#11
Replies: 2
Views: 39

### Re: M#11

M 11 asks " A reaction vessel contains 5.77 g of white phosphorus and 5.77 g of oxygen. The first reaction to take place is the formation of phosphorus(III) oxide. If enough oxygen is present, the oxygen can react further with this oxide to produce phosphorus(V) oxide.(a) What is the limiting r...
Wed Oct 02, 2019 2:22 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar mass vs. Molecular Weight
Replies: 5
Views: 131

### Re: Molar mass vs. Molecular Weight

I have a hard time discerning these two terms as well, but what I have gathered is that the molar mass is the mass per mole of particles, and it is measured in g/mol. This is found using the atomic weight of the constituent elements. The molecular weight is in atomic mass units (amu) and is found us...