Search found 104 matches
- Sun Mar 15, 2020 7:43 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: elementary step
- Replies: 3
- Views: 289
Re: elementary step
An elementary step is one that occurs within a reaction to produce the final products shown in the final balanced equation. It is not typically show in the final equation and includes intermediates.
- Sun Mar 15, 2020 7:41 am
- Forum: Balancing Redox Reactions
- Topic: cathode vs anode
- Replies: 11
- Views: 778
Re: cathode vs anode
In a cell diagram, the anode is on the left side, and the cathode is on the right.
- Sun Mar 15, 2020 7:41 am
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4390
Re: Kc vs Kp
You use Kp for gases if you use partial pressure for gases. You can also change pressure to concentration using PV=nRT and in that case, you would use Kc since you’re now using concentrations.
- Sun Mar 15, 2020 7:39 am
- Forum: Zero Order Reactions
- Topic: 0 order
- Replies: 7
- Views: 645
Re: 0 order
That is when a reaction rate only depends on k. So, if you’re given a table of different concentrations and k’s, you would see that a change in concentration doesn’t change k.
- Sun Mar 15, 2020 7:37 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Delta S
- Replies: 8
- Views: 1367
Re: Delta S
Delta S total is the change in entropy in the system and surrounds. You should just add the change in entropy of the system and change in entropy of the surroundings.
- Sat Mar 07, 2020 8:35 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Reducing Mass of Electrode
- Replies: 6
- Views: 585
Re: Reducing Mass of Electrode
The cell potential does not depend on the mass of an electrode.
- Sat Mar 07, 2020 8:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Concentration cell
- Replies: 8
- Views: 575
Re: Concentration cell
A concentration cell has the same anode and cathode but the concentrations on either side are different, so in a cell diagram you’d indicate that.
- Sat Mar 07, 2020 8:32 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: intermediates
- Replies: 4
- Views: 402
Re: intermediates
Intermediated are not in the overall rate law expression because they get created and used up during the reaction.
- Sat Mar 07, 2020 8:31 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: finding n in G=-nFE
- Replies: 15
- Views: 987
Re: finding n in G=-nFE
You need to write out the half reactions first. When you combine the half reactions, n is the number of electrons on either side of the equation (they cancel each other out).
- Sat Mar 07, 2020 6:15 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: the intermediate in a reaction
- Replies: 10
- Views: 683
Re: the intermediate in a reaction
The intermediate is never in the rate law expression because intermediates get used up in the intermediate steps. The rate law only includes substances present in the end of the reaction.
- Sun Mar 01, 2020 9:29 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n value
- Replies: 9
- Views: 566
Re: n value
The n value is the number of electrons in a reaction.
- Sat Feb 29, 2020 10:14 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Activation Energy
- Replies: 16
- Views: 1435
Re: Activation Energy
Activation energy is the minimum amount of energy required to induce a reaction. On a diagram, it is the distance between the energy of the reactants and peak of the “hump”.
- Sat Feb 29, 2020 10:07 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: electrolysis
- Replies: 3
- Views: 257
Re: electrolysis
Electrolysis is when a non-spontaneous reaction is driven by a current.
- Sat Feb 29, 2020 10:04 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode vs Cathode
- Replies: 15
- Views: 836
Re: Anode vs Cathode
Yes, the anode is written on the left side and it is the one being oxidized. An easy way to remember this is “an ox” (anode oxidized) and “red cat” (cathode reduced).
- Sat Feb 29, 2020 10:00 am
- Forum: Balancing Redox Reactions
- Topic: Homework redox reactions
- Replies: 2
- Views: 200
Re: Homework redox reactions
The reducing agent causes reduction of other species, and the oxidizing agent causes oxidation of other species. So the reducing agent is oxidized by the oxidizing agent while the oxidizing agent is reduced by the reducing agent.
- Sun Feb 23, 2020 11:48 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: porous disc
- Replies: 5
- Views: 401
Re: porous disc
A porous disc doesn’t the same thing as a salt bridge. They both ensure electron flow throughout the system.
- Sun Feb 23, 2020 11:43 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: salt bridge
- Replies: 5
- Views: 453
Re: salt bridge
The salt bridge allows for the flow of electrons.
- Sun Feb 23, 2020 11:35 am
- Forum: Balancing Redox Reactions
- Topic: Oxidizing/reducing agent
- Replies: 7
- Views: 494
Re: Oxidizing/reducing agent
An oxidizing agent is what is being reduced and a reducing agent is what is being oxidized.
- Sun Feb 23, 2020 10:54 am
- Forum: Balancing Redox Reactions
- Topic: Oxidizing/Reducing Agents
- Replies: 11
- Views: 781
Re: Oxidizing/Reducing Agents
Oxidizing agents are what’s being reduced and reducing agents are what’s being oxidized.
- Sat Feb 22, 2020 11:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: relevance of salt bridge
- Replies: 9
- Views: 558
Re: relevance of salt bridge
Salt bridges allow for electron flow between beakers.
- Wed Feb 19, 2020 1:39 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Intensive vs. Extensive
- Replies: 15
- Views: 1297
Re: Intensive vs. Extensive
Intensive properties don't depend on the amount of a substance, while extensive properties do. For example, density is intensive but mass is extensive.
- Wed Feb 19, 2020 1:38 am
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Spontaneous
- Replies: 20
- Views: 1177
Re: Spontaneous
Spontaneous reactions are described as having a negative Gibbs free energy.
- Wed Feb 19, 2020 1:36 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Adiabatic systems
- Replies: 3
- Views: 306
Re: Adiabatic systems
Yes, the definition is adiabatic is when heat doesn't transfer.
- Wed Feb 19, 2020 1:34 am
- Forum: Ideal Gases
- Topic: pv=nrt
- Replies: 19
- Views: 1107
Re: pv=nrt
Yes, this equation can be used at any time as long as these states remain constant.
- Wed Feb 19, 2020 1:34 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: midterm question// Concentration ratio [ENDORSED]
- Replies: 9
- Views: 666
Re: midterm question// Concentration ratio [ENDORSED]
You have to think about how Ka=[A][H+]/[CB] (CB being conjugate base). By rearranging the equation, you can get Ka/[H+] = [A]/[CB], which is a ratio.
- Sun Feb 09, 2020 10:23 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Ideal Gasses
- Replies: 2
- Views: 166
Re: Ideal Gasses
Yes, we should assume this unless the question states otherwise.
- Sun Feb 09, 2020 10:23 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Midterm Material
- Replies: 10
- Views: 500
Re: Midterm Material
Yes, it will but just the basics since he only went over it a little bit.
- Sun Feb 09, 2020 10:21 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE BOX
- Replies: 27
- Views: 758
Re: ICE BOX
When it’s smaller than 10^-3
- Sun Feb 09, 2020 10:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong Acids
- Replies: 6
- Views: 290
Re: Strong Acids
You need to memorize the strong acids (there are only a few) and strong bases are elements in the first 2 columns and OH
- Sun Feb 09, 2020 10:19 pm
- Forum: Student Social/Study Group
- Topic: Midterm Studying
- Replies: 5
- Views: 346
Re: Midterm Studying
One thing you could do is look at the individual topic files he posts on his website. There’s a list of things you should know for each section and I use it like a checklist :)
- Sat Feb 01, 2020 3:13 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Math Resources
- Replies: 8
- Views: 233
Re: Math Resources
Yes, they are on his website under math assistance!
- Sat Feb 01, 2020 3:08 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Strong/weak acids & bases
- Replies: 14
- Views: 895
Re: Strong/weak acids & bases
Yes, the best way is to memorize the strong acids and bases (there aren’t too many). In general, a strong acids start with H and strong bases end with OH. Everything else you can assume is weak
- Sat Feb 01, 2020 3:03 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 17
- Views: 682
Re: Phase Changes
Yes, because the energy from the temperature is used to break/create bonds between molecules for their phase change.
- Sat Feb 01, 2020 2:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Material
- Replies: 13
- Views: 664
Re: Midterm Material
It’s everything up to and including thermodynamics. There are review sessions posted on his website.
- Sat Feb 01, 2020 2:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter + Heat Transfer
- Replies: 4
- Views: 85
Re: Calorimeter + Heat Transfer
When heat is lost (exothermic) there is a negative sign since q indicates heat gained. So when -q=q one thing loses heat and the other thing gains (+q) that heat lost.
- Fri Jan 24, 2020 5:43 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Polyprotic Acids
- Replies: 6
- Views: 413
Re: Polyprotic Acids
K1 is when an acid/base dissociates for the first time. K2 is when the resulting conjugate base/acid from the previous reaction dissociates a second time.
- Fri Jan 24, 2020 5:41 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Transition Temp.
- Replies: 6
- Views: 324
Re: Phase Transition Temp.
Temperature remains constant during a phase change because the energy that would increase temperature is instead being used to break bonds for a phase change.
- Fri Jan 24, 2020 5:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q<K
- Replies: 11
- Views: 228
Re: Q<K
This is because the numerator of Q needs to increase to reach equilibrium (K value), and the concentration of products is the numerator.
- Fri Jan 24, 2020 5:37 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pka
- Replies: 4
- Views: 271
Re: pka
A higher pKa means a weaker acid since pKa is -log [acid]
- Fri Jan 24, 2020 5:37 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Steam
- Replies: 5
- Views: 127
Re: Steam
Steam causes more severe burns because it has more heat energy since there is a phase change from liquid to gas.
- Sun Jan 19, 2020 4:56 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pH vs. pOH
- Replies: 13
- Views: 391
Re: pH vs. pOH
To calculate pOH, you use the concentration of a base. Alternatively, you calculate the pH using the concentration of an acid. The question may also include a Ka or Kb value. The Ka indicates the equilibrium constant of an acid (uses concentration of hydronium ions), and the Kb indicates the equilib...
- Sun Jan 19, 2020 4:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to omit "x-term"
- Replies: 6
- Views: 367
Re: When to omit "x-term"
You can omit the x term when the K value is less than 10^-3.
- Sun Jan 19, 2020 4:47 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Strong Acids/Bases vs. Weak Acids/Bases
- Replies: 9
- Views: 224
Re: Strong Acids/Bases vs. Weak Acids/Bases
You have to memorize the strong acids and bases. If the compound is not one of the memorized acids/bases, we assume they’re weak. In general, strong acids start with H and strong bases end with OH. Aside from that, there are a few obscure ones you should memorize.
- Sun Jan 19, 2020 4:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH values of weak and strong acids
- Replies: 6
- Views: 284
Re: pH values of weak and strong acids
Acids make solutions that have a pH from 1-7, stronger acids making lower pH values than weak acids. pH doesn’t depend on concentration, but the strength of the acid/base.
- Sun Jan 19, 2020 4:40 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: ICE table
- Replies: 11
- Views: 332
Re: ICE table
Yes, we have to memorize strong acids and bases. The common rule is that strong acids start with H and strong bases end with OH. Then there are a few other obscure strong acids and bases you should memorize.
- Fri Jan 10, 2020 10:26 am
- Forum: Ideal Gases
- Topic: Difference between K and Q
- Replies: 9
- Views: 276
Re: Difference between K and Q
K is used for when the reaction is at equilibrium, while Q is used for when the reaction is not. A reaction at equilibrium moves at a different rate than when it’s not at equilibrium. Therefore, they’re different numbers that you can compare to determine which direction the reaction favors.
- Fri Jan 10, 2020 10:24 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units for K
- Replies: 10
- Views: 241
Re: Units for K
The equilibrium constant K is the ratio of reactants to products, and ratios don’t have units.
- Fri Jan 10, 2020 10:21 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Do solids and liquids count in Q?
- Replies: 5
- Views: 195
Re: Do solids and liquids count in Q?
Q is calculated the same way as K, so you only include gases and aqueous solutions.
- Fri Jan 10, 2020 10:19 am
- Forum: Ideal Gases
- Topic: Reaction Quotient (Q)
- Replies: 8
- Views: 289
Re: Reaction Quotient (Q)
The reaction quotient is the rate of the equation when it’s not at equilibrium. This is important because you use it to determine which “direction” the reaction favors (towards products or reactants) by comparing it to the equilibrium constant K.
- Fri Jan 10, 2020 10:17 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc and Kp
- Replies: 4
- Views: 166
Re: Kc and Kp
You use Kp for gases because it indicates partial pressure, since gases don’t really have a “concentration”. Kc is for concentrations of solids, liquids, and aqueous solutions.
- Sat Dec 07, 2019 2:15 am
- Forum: Identifying Acidic & Basic Salts
- Topic: deciding whether the solution of a salt is basic, acidic, or neutral
- Replies: 5
- Views: 594
Re: deciding whether the solution of a salt is basic, acidic, or neutral
You should start by writing out the chemical equation of the salt in water. If the product has H+/H3O+, then the solution is acidic. If the product has OH-. then the solution is basic.
- Sat Dec 07, 2019 2:12 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH in increasing temp
- Replies: 2
- Views: 155
Re: pH in increasing temp
Yes, but Dr. Lavelle said this is a chem 14b (I think) topic so we don't need to know this.
- Sat Dec 07, 2019 2:10 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Weak vs Strong acids and bases
- Replies: 6
- Views: 452
Re: Weak vs Strong acids and bases
pH shows the concentration of hydronium ions in the solution. Weak acids result in a low concentration of hydronium ions because the hydrogen doesn't dissociate easily, therefore resulting in a less acidic solution (pH closer to 7).
- Sat Dec 07, 2019 2:08 am
- Forum: Conjugate Acids & Bases
- Topic: Oxoacids
- Replies: 4
- Views: 448
Re: Oxoacids
An oxoacid is an acid with oxygen in the compound. It is important to note that metallic oxides are strong acids.
- Sat Dec 07, 2019 2:06 am
- Forum: Calculating the pH of Salt Solutions
- Topic: pH vs. pOH
- Replies: 17
- Views: 2272
Re: pH vs. pOH
pH indicates the concentration of hydronium, while pOH indicates the concentration of hydroxide. You can think of them as the extent of acidity and basicity (respectively).
- Sat Dec 07, 2019 1:42 am
- Forum: Dipole Moments
- Topic: London Dispersion Forces
- Replies: 5
- Views: 401
Re: London Dispersion Forces
Yes, because all molecules have electrons, and LDFs occur when electron clouds are more dense in one direction.
- Sat Dec 07, 2019 12:51 am
- Forum: Naming
- Topic: Naming Anionic Ligands
- Replies: 3
- Views: 231
Re: Naming Anionic Ligands
You can use either on the test, although Lavelle focuses on the older version in lecture.
- Thu Dec 05, 2019 2:11 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: using Ka and Pka
- Replies: 4
- Views: 317
Re: using Ka and Pka
Ka is the dissociation constant and it shows how easily acids dissociate ([H+][anion]/[H-A]). The higher the Ka, the stronger the acid. PKa = -log[Ka]. The higher the PKa, the weaker the acid.
- Thu Dec 05, 2019 2:06 pm
- Forum: Student Social/Study Group
- Topic: coordination compounds
- Replies: 2
- Views: 252
Re: coordination compounds
Chelating compounds create a ring when they create bonds, and polydentate compounds have multiple ligands. Compounds can be both chelating and polydentate, like CO3^-2
- Thu Nov 28, 2019 3:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Linear VSEPR model
- Replies: 21
- Views: 1260
Re: Linear VSEPR model
A molecule has a linear shape if it is bonded to 2 atoms and has no lone pairs, or bonded to 2 atoms and has 3 lone pairs.
- Thu Nov 28, 2019 3:45 pm
- Forum: Bronsted Acids & Bases
- Topic: Acid vs Base
- Replies: 4
- Views: 309
Re: Acid vs Base
A Bronsted acid is distinguished by starting with H, and a Bronsted base usually ends with OH.
- Thu Nov 28, 2019 3:40 pm
- Forum: Naming
- Topic: Iron as the central metal
- Replies: 2
- Views: 91
Re: Iron as the central metal
Ferrate is the name for [FeO4]^-2. Ferrous is for the cation Fe^2+ or iron(II).
- Thu Nov 28, 2019 3:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: molecular shape
- Replies: 8
- Views: 500
Re: molecular shape
You look at the regions of electron density. Count the number of bonds and lone electron pairs around the central atom. That shows you the VSEPR formula (AXE), and you can determine the molecular shape.
Re: Oxidation
An oxidation number is the number of electrons lost or gained when making a chemical bond. If it is a negative number, the atom will gain electrons. If it is a positive number, the atom will lose electrons.
- Sun Nov 24, 2019 7:11 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 4055
Re: Bent vs linear
A bent molecule has one or two lone pairs, while a linear molecule has three lone pairs or none.
- Sun Nov 24, 2019 7:09 pm
- Forum: Naming
- Topic: Order in Naming
- Replies: 12
- Views: 673
Re: Order in Naming
The general rule is to put the atomic symbol in alphabetical order.
- Sun Nov 24, 2019 7:08 pm
- Forum: Hybridization
- Topic: Sigma and Pi bonds
- Replies: 13
- Views: 652
Re: Sigma and Pi bonds
When labeling, one of the bonds is a pi bond, and the other is a sigma bond. Similarly, in a triple bond, one is a sigma bond, and the other two are pi bonds.
- Sun Nov 24, 2019 7:07 pm
- Forum: Lewis Acids & Bases
- Topic: HCl vs HF
- Replies: 19
- Views: 1316
Re: HCl vs HF
Because fluorine has a higher electronegativity than chlorine, its bond with hydrogen is stronger. Therefore, HCl dissociates more easily, making it a stronger acid due to its complete ionization.
- Sun Nov 24, 2019 7:03 pm
- Forum: Hybridization
- Topic: Lone pairs
- Replies: 9
- Views: 551
Re: Lone pairs
Electron pairs are still important in the shape of the molecule, as they interact with the electron clouds of the atoms bonded to the central atom. Hybrid orbitals depend on the molecular shape, therefore, electron pairs are included in hybridization.
- Sat Nov 16, 2019 11:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 4
- Views: 299
Re: Bond Angles
I think you can just write what the textbook requires, which is <109.5. But you should write exact numbers for 90, 180, 120 degree angles.
- Sat Nov 16, 2019 11:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polar or non polar?
- Replies: 7
- Views: 501
Re: polar or non polar?
You can kind of think polarity as "unevenness" because electrons are unevenly distributed. Therefore, you can look at how symmetrical a lewis structure is to determine it's polarity. If it is completely symmetrical, then it is most likely nonpolar. If it is not, then it is polar with a sid...
- Sat Nov 16, 2019 11:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: identifying pi & sigma bonds
- Replies: 3
- Views: 216
Re: identifying pi & sigma bonds
Sigma bonds are in single bonds, double bonds, and triple bonds; it's kind of like the first bond. Pi bonds are in double bonds and triple bonds; it's kind of like the subsequent bonds to pi bonds. Single bonds have one sigma bond, double bonds have one sigma bond and one pi bond, and triple bonds h...
- Sat Nov 16, 2019 11:14 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Studying
- Replies: 14
- Views: 861
Re: Final Studying
I've been reviewing the midterm and looking at concepts I didn't fully understand. I'm also doing problems in the textbook since some of the questions may be on the final.
- Sat Nov 16, 2019 4:49 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Electron configuration
- Replies: 7
- Views: 455
Re: Electron configuration
The 4s orbital is lower in energy. However, when it is full, it becomes higher in energy than 3d. This explains why we write electron configurations like 3d^2 4s^2 4p^6.
- Sat Nov 09, 2019 4:58 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bond Strength
- Replies: 8
- Views: 446
Re: Hydrogen Bond Strength
Hydrogen bonds are weaker than ionic and covalent bonds, but hydrogen bonds are the strongest of the intermolecular forces.
- Sat Nov 09, 2019 4:56 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: Dipole-dipole v. Induced Dipole-Induced Dipole
- Replies: 2
- Views: 142
Re: Dipole-dipole v. Induced Dipole-Induced Dipole
A dipole-dipole force is between molecules that are always polar. An induced dipole-induced dipole force is between molecules that have instantaneous dipole moments; the electrons move around, making the molecule temporarily polar.
- Sat Nov 09, 2019 4:49 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: Hydrogen Bonding
- Replies: 4
- Views: 235
Re: Hydrogen Bonding
I think this is because they are very electronegative. Especially because they have small radii, it has strong bonds with hydrogen, which has the smallest radius of all the elements.
- Sat Nov 09, 2019 4:45 pm
- Forum: Bond Lengths & Energies
- Topic: Bonds
- Replies: 6
- Views: 387
Re: Bonds
Sigma bonds are in all bonds, and pi bonds are in double and triple bonds. Single bonds have one sigma bond, double bonds have a sigma and a pi bond, and triple bonds have a sigma and two pi bonds.
- Sat Nov 09, 2019 4:42 pm
- Forum: Bond Lengths & Energies
- Topic: Resonance structure bond lengths?
- Replies: 3
- Views: 214
Re: Resonance structure bond lengths?
Bond length is the distance between the two nuclei of the elements. The electron clouds influence bond lengths by making the elements farther/closer from each other with electron-electron repulsion.
- Sat Nov 02, 2019 4:50 pm
- Forum: Lewis Structures
- Topic: Determining most stable Lewis structure
- Replies: 5
- Views: 266
Re: Determining most stable Lewis structure
Although they are both important, formal charge is slightly more important. Not all lewis structures will be symmetrical.
- Sat Nov 02, 2019 4:49 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electronegativity difference >1.5 but <2
- Replies: 3
- Views: 226
Re: Electronegativity difference >1.5 but <2
This doesn't really answer the question, but it's interesting to note that this also demonstrates how some ionic bonds demonstrate a more covalent character than others. If one bond has a really high electronegativity difference, it demonstrates less covalent character than one that has an electrone...
- Sat Nov 02, 2019 12:39 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Understanding Ionic Radius
- Replies: 3
- Views: 268
Re: Understanding Ionic Radius
Yes, because even though isoelectronic ions have the same number of electrons, they still have differing numbers of protons. When there are more protons in the nucleus, there is a stronger pull. Therefore, isoelectronic ions have the same electron-electron repulsion but different pulls from the nucl...
- Sat Nov 02, 2019 12:32 pm
- Forum: Trends in The Periodic Table
- Topic: Noble Gases
- Replies: 10
- Views: 616
Re: Noble Gases
No, they don't because they have all 8 valence electrons. These trends are based on the fact that elements tend to want to have a full valence shell. For example, ionization energy is the amount of energy it takes to remove an electron. Group 1 has low ionization energy because they want to lose the...
- Sat Nov 02, 2019 12:22 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: General Question about Orbital... Filling..?
- Replies: 5
- Views: 144
Re: General Question about Orbital... Filling..?
The d orbital is lower in energy than the s orbital, so when you write the electron configuration you always write the d orbital first. For example, ... 3d^10 4s^2 4p^6, ... 4d^10 5s^2 etc.
- Thu Oct 24, 2019 8:26 pm
- Forum: Trends in The Periodic Table
- Topic: Aufbau Principle
- Replies: 11
- Views: 566
Re: Aufbau Principle
He might also ask questions that require you to differentiate the three different principles we learned. Ex. what principle explains the electron configuration 1s^2 2s^2 2p^6 for carbon? why can't 1s^2 2s^2 2p^3 (nitrogen) have paired electrons?
- Thu Oct 24, 2019 1:50 pm
- Forum: *Particle in a Box
- Topic: TEST 2
- Replies: 14
- Views: 1301
Re: TEST 2
I think the best way to study is to do practice problems. You learn how to solve a bunch of different problems on the same topic and won't be blindsided if a problem is worded weirdly.
- Thu Oct 24, 2019 1:42 pm
- Forum: Lewis Structures
- Topic: Ion lewis structure
- Replies: 9
- Views: 363
Re: Ion lewis structure
Yes, there are a few exceptions to the octet rule. This includes molecules with an odd number of electrons (ex. nitrogen), molecules with atoms that have more than 8 electrons (ex. sulfur), and molecules with atoms that have less than 8 electrons (ex. boron).
- Thu Oct 24, 2019 1:32 pm
- Forum: Trends in The Periodic Table
- Topic: Ionic Radii
- Replies: 10
- Views: 429
Re: Ionic Radii
Anions are larger because they add another electron, creating more electron-electron repulsion between the valence shell electrons and the electrons in the shell below it (increasing distance between the shells). Cations are smaller because they remove an electron, decreasing the amount of electron-...
- Thu Oct 24, 2019 1:24 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic v.covalent bonds
- Replies: 7
- Views: 324
Re: Ionic v.covalent bonds
Yes, exactly! Also, note that elements in ionic compounds give and take electrons from each other, while elements in covalent compounds share electrons.
- Sun Oct 20, 2019 3:14 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing equations.
- Replies: 35
- Views: 2554
Re: Balancing equations.
A good trick is to write down a mini chart under the equation where you write down the elements and the number of moles for the reactant side and product side. Ie Reactants --> C 3, O 1, H4 Products --> C 1, O 2, H 2. This might help you keep track of your numbers without making your work too messy.
- Sat Oct 19, 2019 3:53 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: HW 1B #27
- Replies: 2
- Views: 180
Re: HW 1B #27
The question is saying the bowling ball is moving at 5+5 m/s (10 m/s) or 5-5 m/s (0 m/s). That's why you multiply the mass by 10 m/s.
- Sat Oct 19, 2019 3:32 pm
- Forum: Trends in The Periodic Table
- Topic: Problem 1.13
- Replies: 2
- Views: 100
Re: Problem 1.13
This is because oxygen has one electron pair in the outer shell, while nitrogen has none. The electron pair contains electron-electron repulsion, making it easier to remove the most loosely bound electron, meaning it has low ionization energy.
- Thu Oct 17, 2019 7:14 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Theoretical vs. Actual Yield
- Replies: 38
- Views: 13881
Re: Theoretical vs. Actual Yield
Actual yield is less than theoretical due to almost unavoidable mistakes, for example, slight inaccuracies in measuring out reactants or some of the product sticking to the side of the beaker when measuring. Theoretical yield is the largest possible yield in a reaction, as it assumes there are no mi...
- Sat Oct 12, 2019 5:10 pm
- Forum: Empirical & Molecular Formulas
- Topic: Mass Percentage Question
- Replies: 9
- Views: 847
Re: Mass Percentage Question
First, write down the molar masses of each element in the compound. Then find the molar mass of the compound by adding the atomic masses of the elements (making sure to account for the additional atoms ex. O2 is 32 g/mol). Finally, find the mass percent for each element using the equation [(molar ma...
- Sat Oct 12, 2019 5:01 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 16
- Views: 882
Re: Atomic Radius
The radius is only measured when the element is in its ground state!
- Sat Oct 12, 2019 4:58 pm
- Forum: Properties of Light
- Topic: c vs. v...
- Replies: 3
- Views: 268
Re: c vs. v...
I think that equation applies only to electromagnetic waves!
- Sat Oct 12, 2019 4:32 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 4
- Views: 1054
Re: Electronegativity
I don't think so, but it should be helpful to know that electronegativity increases the closer it is to fluorine since it's the element with the highest electronegativity.
- Sat Oct 12, 2019 4:18 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent
- Replies: 32
- Views: 43336
Re: Ionic vs Covalent
Ionic bonds are stronger than covalent bonds because elements give/take electrons, whereas elements with covalent bonds share electrons.
- Sat Oct 12, 2019 4:16 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg equation [ENDORSED]
- Replies: 73
- Views: 8692
Re: Rydberg equation [ENDORSED]
You use the Rydberg equation to calculate the wavelength of light released when an electron jumps down to lower energy levels.
- Sun Oct 06, 2019 9:18 pm
- Forum: General Science Questions
- Topic: Order of Elements When Writing Out a Compound
- Replies: 8
- Views: 509
Re: Order of Elements When Writing Out a Compound
I think it's supposed to be in alphabetical order (ex. hydrogen, carbon, chlorine, oxygen). After taking chem for a while and getting used to seeing a bunch of different compounds, putting them in order will become automatic. :)