Search found 108 matches
- Sun Mar 15, 2020 6:05 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 3
- Views: 93
Re: Catalysts
A catalyst is first a reactant and is used up, then is a product and is formed.
- Sat Mar 14, 2020 8:45 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam Time
- Replies: 13
- Views: 368
Re: Final Exam Time
The exam starts at 11:15am and is over at 2:45pm! It will most likely close at 2:45pm and submit whatever you had completed on it.
- Sat Mar 14, 2020 2:05 pm
- Forum: General Rate Laws
- Topic: Rate-determining step
- Replies: 7
- Views: 196
Re: Rate-determining step
It will probably be given to you in the question!
- Fri Mar 13, 2020 2:52 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Slowest step
- Replies: 9
- Views: 187
Re: Slowest step
The slow step determines the rate of the full reaction because no matter how fast the other steps are, the reaction is only complete once the slow step has been completed.
- Fri Mar 13, 2020 2:48 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Slow step
- Replies: 7
- Views: 160
Re: Slow step
There isn't a numerical value that you would use to deduce if it's a slow step or not. It would just be the slowest step out of all of the steps.
- Wed Mar 11, 2020 5:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2
- Replies: 3
- Views: 86
Re: Test 2
My TA emailed us about where to pick them up! You should get one from yours soon!
- Sun Mar 08, 2020 9:51 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: A
- Replies: 8
- Views: 102
Re: A
[A]0 represents the initial concentration and [A] represents the concentration of the reactants!
- Sun Mar 08, 2020 9:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: TesT 2
- Replies: 3
- Views: 59
Re: TesT 2
I'm pretty sure you'll get them back during your section this week !
- Sun Mar 08, 2020 3:04 pm
- Forum: First Order Reactions
- Topic: rate constants
- Replies: 20
- Views: 372
Re: rate constants
Yes! Rate constants are always positive because concentrations cannot be negative values.
- Sun Mar 08, 2020 2:58 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Adding carbon (gr) to cell diagrams
- Replies: 4
- Views: 92
Re: Adding carbon (gr) to cell diagrams
Adding carbon graphite isn't as common as adding platinum but it can be written wherever platinum can be written! Writing carbon graphite is equivalent to writing platinum in this circumstance.
- Tue Mar 03, 2020 12:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 6
- Views: 93
Re: Platinum
You add Pt to your cell diagram when there is no conducting solid in any of your half-reactions.
- Sun Mar 01, 2020 8:50 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: cell diagrams
- Replies: 4
- Views: 111
Re: cell diagrams
Use Pt in your cell diagram if there is no solid present in the reaction!
- Sun Mar 01, 2020 3:25 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cells
- Replies: 6
- Views: 92
Re: Galvanic Cells
Yes! Galvanic cells are spontaneous and therefore, the E must be positive.
- Sun Mar 01, 2020 3:21 pm
- Forum: Zero Order Reactions
- Topic: Deriving Equations
- Replies: 7
- Views: 682
Re: Deriving Equations
I'm sure there are a few that we'll have to derive on our own but I think he'll give us every equation we need to do so with on the equation sheet!
- Sun Mar 01, 2020 3:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: salt bridge
- Replies: 11
- Views: 177
Re: salt bridge
The purpose of a salt bridge is to maintain charge balance.
- Sat Feb 29, 2020 1:40 pm
- Forum: Balancing Redox Reactions
- Topic: Reducing/Oxidizing Agents
- Replies: 13
- Views: 176
Re: Reducing/Oxidizing Agents
Whatever is being oxidized is the reducing agent and whatever is being reduced is the oxidizing agent.
- Sat Feb 29, 2020 1:30 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2
- Replies: 19
- Views: 282
Re: Test 2
Test two is going to cover everything from the second page of outline four and all of outline five !
- Sun Feb 23, 2020 7:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Half reactions
- Replies: 13
- Views: 225
Re: Half reactions
Half reactions are the reduction and oxidation reactions that make up a redox reaction.
- Sun Feb 23, 2020 2:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: salt bridge
- Replies: 5
- Views: 72
Re: salt bridge
The salt bridge allows ion transfer between the two solutions and is used to maintain charge !
- Sun Feb 23, 2020 2:09 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Gibbs free energy
- Replies: 5
- Views: 107
Re: Gibbs free energy
It represents the charge of one mole of electrons.
- Sun Feb 23, 2020 1:55 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: adding/subtracting half-redox rxns
- Replies: 4
- Views: 84
Re: adding/subtracting half-redox rxns
Since E is an intensive property, it doesn't depend on how many times the reaction occurs and therefore, will never change! H is an extensive property, which is why you can use Hess's Law.
- Sat Feb 22, 2020 8:49 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: property of E
- Replies: 6
- Views: 94
Re: property of E
E doesn't change because it's an intensive property! It doesn't depend on how many times the reaction occurs.
- Sun Feb 16, 2020 8:32 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: memorize
- Replies: 14
- Views: 276
Re: memorize
After taking the midterm, I'm pretty certain he'll provide us with any constants we may need for an exam.
- Sun Feb 16, 2020 8:29 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: S = kblnW explanation
- Replies: 4
- Views: 81
Re: S = kblnW explanation
S= entropy
kB= boltzmann constant
ln= natural log
W= number of states^(number of atoms or molecules)
kB= boltzmann constant
ln= natural log
W= number of states^(number of atoms or molecules)
- Sun Feb 16, 2020 8:28 pm
- Forum: Van't Hoff Equation
- Topic: delta s
- Replies: 9
- Views: 145
Re: delta s
Because standard conditions don't change !
- Sun Feb 16, 2020 8:26 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: S = 0
- Replies: 21
- Views: 395
Re: S = 0
It's zero in an isothermal reversible reaction.
- Sun Feb 16, 2020 8:17 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous
- Replies: 13
- Views: 241
Re: Spontaneous
A reaction is spontaneous when delta G is negative!
- Sat Feb 08, 2020 10:53 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: q rev
- Replies: 9
- Views: 90
Re: q rev
'Rev' just means reversible so q rev is used when calculating the heat for a reversible reaction.
- Sat Feb 08, 2020 10:49 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Units
- Replies: 4
- Views: 67
Re: Units
The units for change in enthalpy is J/K. And no, the units for temperature will not remain! They'll end up cancelling out.
- Sat Feb 08, 2020 10:46 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy and Pressure
- Replies: 3
- Views: 65
Re: Entropy and Pressure
Yes! When pressure increases, entropy decreases because volume decreases.
- Tue Feb 04, 2020 8:18 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Boltzman Constant
- Replies: 4
- Views: 51
Re: Boltzman Constant
The unit of the boltzmann constant is J/K.
- Mon Feb 03, 2020 5:57 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: ∆U
- Replies: 8
- Views: 104
Re: ∆U
It represents the change in the internal energy of a system !
- Sun Feb 02, 2020 7:14 pm
- Forum: Calculating Work of Expansion
- Topic: Two different equations
- Replies: 2
- Views: 39
Re: Two different equations
The difference between the two work equations is that one includes the integral and one does not. You use the work equation without the integral when pressure is constant.
- Sun Feb 02, 2020 7:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1 #6
- Replies: 6
- Views: 108
Re: Test 1 #6
It's because HF is actually a weak acid, meaning it doesn't dissociate completely!
- Sat Feb 01, 2020 9:36 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: isolated system
- Replies: 13
- Views: 156
Re: isolated system
Another example could be hot coffee in a thermos.
- Sat Feb 01, 2020 9:32 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Thermodynamics Outline
- Replies: 5
- Views: 62
Re: Thermodynamics Outline
I think we probably will end up having to know most if not all of the thermodynamics outline for the midterm.
- Sat Feb 01, 2020 9:30 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy units
- Replies: 4
- Views: 53
Re: Entropy units
I'm sure you can use kJ/K for entropy if it matches the units of everything else in the problem you are working on but the SI unit for entropy is K/J!
- Sun Jan 26, 2020 1:06 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Exothermic reaction
- Replies: 18
- Views: 275
Re: Exothermic reaction
If a reaction is exothermic, an increase in its temperature will cause the reaction to shift to the left and a decrease in its temperature will cause the reaction to shift to the right!
- Sat Jan 25, 2020 9:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Energy of the reactants
- Replies: 6
- Views: 56
Re: Energy of the reactants
The energy of the products being higher than the reactants is due to the products absorbing heat from their surroundings, meaning the reaction is an endothermic reaction.
- Sat Jan 25, 2020 7:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Excluding H2O from Ka and Kb
- Replies: 5
- Views: 60
Re: Excluding H2O from Ka and Kb
Solids and liquids don't affect the value of K, therefore we don't include them in the calculations!
- Sat Jan 25, 2020 7:12 pm
- Forum: Phase Changes & Related Calculations
- Topic: Reading?
- Replies: 5
- Views: 69
Re: Reading?
I usually read the sections he has assigned for homework on the outline that we're focusing on in lecture at that time !
- Sat Jan 25, 2020 6:36 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Different methods
- Replies: 4
- Views: 33
Re: Different methods
What the question contains will help determine what method you should use!
- Sat Jan 25, 2020 6:35 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy of formation
- Replies: 4
- Views: 58
Re: Standard Enthalpy of formation
The unit for standard enthalpy of formation is kJ/mol!
- Mon Jan 20, 2020 8:41 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Does order matter?
- Replies: 5
- Views: 48
Re: Does order matter?
No, as long as the products are in the numerator and the reactants are in the denominator the order of which one you write first does not matter.
- Sun Jan 19, 2020 6:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Endo vs. Exothermic
- Replies: 5
- Views: 47
Re: Endo vs. Exothermic
If a reaction requires heat it is endothermic. If a reaction gives off heat it is exothermic.
- Sun Jan 19, 2020 4:40 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Strong Acids/Bases vs. Weak Acids/Bases
- Replies: 9
- Views: 66
Re: Strong Acids/Bases vs. Weak Acids/Bases
Strong acids and bases dissociate completely whereas weak acids and bases do not. I would just memorize the strong acids/bases to make working out problems a little easier. There is a list of both in the textbook.
- Thu Jan 16, 2020 1:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solids and liquids
- Replies: 3
- Views: 20
Re: Solids and liquids
Solids and liquids don't affect the value of K, so we leave them out.
- Tue Jan 14, 2020 5:27 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: HW 5j #5
- Replies: 5
- Views: 60
Re: HW 5j #5
The answer is no change because the number of moles on both the reactant and product sides are the same.
- Sun Jan 12, 2020 10:53 am
- Forum: Ideal Gases
- Topic: aqueous elements in eq calculation
- Replies: 8
- Views: 76
Re: aqueous elements in eq calculation
Aqueous solutions would be included in the equilibrium equation because these effect the value of K but solids and liquids aren't included because they don't affect K in any way.
- Sun Jan 12, 2020 10:46 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Q
- Replies: 3
- Views: 34
Re: K and Q
Because they don't change the value of K in any way, so you can disregard them while writing the K or Q expression.
- Sun Jan 12, 2020 10:44 am
- Forum: Administrative Questions and Class Announcements
- Topic: Test Dates
- Replies: 3
- Views: 63
Re: Test Dates
Test one starts on January 21st and test two starts on February 25th. So, whenever you have ur discussion after or on that date is when you'll have your tests.
- Sun Jan 12, 2020 10:38 am
- Forum: Ideal Gases
- Topic: Test 1
- Replies: 7
- Views: 93
Re: Test 1
I'm not exactly sure but maybe a good way to gauge it would be to see how many ideal gas homework problems he's assigned? I would just be as comfortable with ideal gases as I could be to be prepared.
- Sat Jan 11, 2020 1:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K values
- Replies: 4
- Views: 61
Re: K values
K = 1 is rare because it's not common for reactants and products to have the same stability.
- Sat Dec 07, 2019 1:55 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Electron Configuration
- Replies: 10
- Views: 206
Re: Electron Configuration
4s would come after 3d!! In high school most of us learned to put the 4s before the 3d since they are in that order on the periodic table, but energy level wise the 4s would come after 3d. To put it simply, whenever you're doing electron configuration, put them in numerical order.
- Sat Dec 07, 2019 1:49 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligand Charges
- Replies: 3
- Views: 66
Re: Ligand Charges
I would memorize them, which seems like a hassle but honestly the more practice problems you do, the easier it gets to memorize.
- Sat Dec 07, 2019 1:46 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Naming Coordination Compounds on Final
- Replies: 2
- Views: 62
Re: Naming Coordination Compounds on Final
I would! It's probably the best way to ensure that you can name anything he might give us on the final.
- Thu Dec 05, 2019 10:59 am
- Forum: Octet Exceptions
- Topic: radicals
- Replies: 3
- Views: 172
Re: radicals
You always place radicals on the most electronegative atom!
- Thu Dec 05, 2019 10:52 am
- Forum: Hybridization
- Topic: S Character
- Replies: 4
- Views: 59
Re: S Character
S character refers to the contribution of the s-orbital in hybridization. For example in a sp2 notation, there would be 33% s character and 66% p character. In a sp3 notation, there would be 25% s character and 75% p character.
- Sun Dec 01, 2019 6:59 pm
- Forum: General Science Questions
- Topic: Week 10 Classes
- Replies: 7
- Views: 223
Re: Week 10 Classes
alex_4C wrote:Is our final on the 8th or 9th?
Our final is on the 8th at 11:30am.
- Sun Dec 01, 2019 5:25 pm
- Forum: Student Social/Study Group
- Topic: final
- Replies: 4
- Views: 119
Re: final
Honestly everything we've learned in class will most likely make its way on the final in one way or another. I would just look at the outlines from his website and continue to do the hw problems he's provided to try to be well prepared for it.
- Sun Dec 01, 2019 12:34 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis vs. Bronsted
- Replies: 3
- Views: 41
Re: Lewis vs. Bronsted
In the book it mentions that when they say 'acid' they are referring to the Brønsted acid so I'm assuming that applies for lecture as well. I think if he were to mention lewis acids/bases he would say 'lewis acid' or 'lewis base'. And I would definitely know how to differentiate the two for the final!
- Sun Dec 01, 2019 11:55 am
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Strong and Weak Acids
- Replies: 7
- Views: 129
Re: Strong and Weak Acids
There is a list of strong acids in the book that I would recommend having memorized!
HBr, HCl, HI, HNO3, HClO4, HClO3, H2SO4
HBr, HCl, HI, HNO3, HClO4, HClO3, H2SO4
- Sun Dec 01, 2019 11:50 am
- Forum: Amphoteric Compounds
- Topic: Identifying Them?
- Replies: 12
- Views: 280
Re: Identifying Them?
On the periodic table, there is a diagonal band of amphoteric oxides closely matching the diagonal band of metalloids. You can also tell if it is able to accept and donate hydrogen ions. As for identifying them in a chemical equation, it's not necessarily important to know if it's amphoteric, just w...
- Sat Nov 30, 2019 6:25 pm
- Forum: Amphoteric Compounds
- Topic: amphoteric oxides
- Replies: 3
- Views: 48
Re: amphoteric oxides
Yes! All amphoteric compounds are oxides.
- Sat Nov 30, 2019 6:24 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted Acids and Bases
- Replies: 3
- Views: 50
Re: Bronsted Acids and Bases
Yes water is considered both an acid and a base. Just as the above response says, amphoteric compounds have the characteristic of both. You can find amphoteric oxides on the period table in a diagonal band closely matching the diagonal band of the metalloids.
- Sat Nov 30, 2019 6:19 pm
- Forum: Lewis Acids & Bases
- Topic: Identifying lewis acids and bases
- Replies: 4
- Views: 45
Re: Identifying lewis acids and bases
A lewis acid is an electron pair acceptor and a lewis base is an electron pair donor. This differs from Brønsted acids and bases; Brønsted acid is a proton donor and a Brønsted base is a proton acceptor.
- Sun Nov 24, 2019 6:13 pm
- Forum: Hybridization
- Topic: Strength of sigma vs pi bonds
- Replies: 6
- Views: 59
Re: Strength of sigma vs pi bonds
Sigma bonds are stronger than pi bonds because they overlap head on and a greater overlap = a stronger bond. Pi bonds overlap from the side therefore their bond is not as strong because the overlap is not as much.
- Sun Nov 24, 2019 6:10 pm
- Forum: Hybridization
- Topic: bonds
- Replies: 2
- Views: 62
Re: bonds
A sigma bond is symmetrical with no nodal planes with respect to the internuclear axis but a pi bond has a single nodal plane with respect to the internuclear axis.
- Sun Nov 24, 2019 6:01 pm
- Forum: Naming
- Topic: Trans and Cis
- Replies: 8
- Views: 195
Re: Trans and Cis
Yes, so if two of the same atoms are on the same side of the central atom then it is cis- and if they are on opposite sides then it is trans-.
- Tue Nov 19, 2019 11:24 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 bond
- Replies: 3
- Views: 51
Re: hydrogen bond
It can occur when a hydrogen is bonded to a nitrogen, oxygen, or fluoride.
- Sun Nov 17, 2019 3:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs and bond angles
- Replies: 4
- Views: 46
Re: Lone pairs and bond angles
Yes, a lone pair decreases the bond angles. For example, in NH3 since there is a lone pair the bond angles will be around 107 degrees rather than the 109.5 degrees that shape usually gives.
- Sun Nov 17, 2019 1:13 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: Hydrogen Bonds
- Replies: 3
- Views: 66
Re: Hydrogen Bonds
Hydrogen bonds are the strongest types of dipole-dipole interactions. Ion-ion are the strongest type of IMF!
- Sun Nov 17, 2019 12:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.21 d
- Replies: 2
- Views: 33
Re: 2E.21 d
In lecture he mentioned that we aren't expected to know the value of the actual angle and that we should just be able to determine that it would be less than 109.5 degrees.
- Sun Nov 17, 2019 12:56 pm
- Forum: Dipole Moments
- Topic: ion-dipole moments
- Replies: 3
- Views: 58
Re: ion-dipole moments
Yes, ion-dipole is stronger than dipole-dipole. The order goes: ion-ion, ion-dipole, dipole-dipole, dipole-induced dipole, induced dipole-induced dipole.
- Thu Nov 14, 2019 2:11 pm
- Forum: Dipole Moments
- Topic: Polarity
- Replies: 12
- Views: 176
Re: Polarity
You can look at the difference in electronegativity to figure out if a molecule is polar or look at its shape. If a molecule is symmetric it is non-polar, i.e. CH4 would be non-polar because it's symmetrical. An example of a polar molecule is NH3, which is not symmetric.
- Thu Nov 14, 2019 1:58 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: Polar Vs Nonpolar
- Replies: 7
- Views: 131
Re: Polar Vs Nonpolar
A polar molecule occurs when the molecule is not symmetric, i.e. when one side has a positive charge and the other side has a negative charge.
- Thu Nov 14, 2019 1:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework 2E.11
- Replies: 3
- Views: 41
Re: Homework 2E.11
The VSEPR formula is AXnEn.
A: central atom
Xn: number of bonding electrons (electrons connected to central atom)
En: number of lone pairs
Draw the lewis structure and you'll find everything you need for the formula!
A: central atom
Xn: number of bonding electrons (electrons connected to central atom)
En: number of lone pairs
Draw the lewis structure and you'll find everything you need for the formula!
- Sun Nov 10, 2019 3:01 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: Test 2
- Replies: 6
- Views: 122
Re: Test 2
I think test two covers everything we have learned after the first midterm.
- Sun Nov 10, 2019 1:10 pm
- Forum: Octet Exceptions
- Topic: Octet Exception
- Replies: 8
- Views: 253
Re: Octet Exception
Any element in and after the third period can have an expanded octet due to them having more than just p-orbitals.
- Sun Nov 10, 2019 11:53 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: Is there a difference between Van der Waals and LDF?
- Replies: 5
- Views: 98
Re: Is there a difference between Van der Waals and LDF?
Van der Waals is usually used to describe all intermolecular forces. LDF is always included in it.
- Sun Nov 10, 2019 11:36 am
- Forum: Dipole Moments
- Topic: HW this week
- Replies: 6
- Views: 72
Re: HW this week
I would maybe ask your TA just to be sure. If your discussion session is in the beginning of the week, I'm sure doing problems from chemical bonds is okay.
- Sun Nov 03, 2019 10:26 am
- Forum: Lewis Structures
- Topic: Lowest Energy
- Replies: 2
- Views: 49
Re: Lowest Energy
Ideally you want your central atom to have a formal charge of zero or as close as you can get to it. The octet rule can only be broken if that element is able to break it. Elements from period three or higher have d-orbitals, allowing them to accommodate for more electrons. So just make sure that if...
- Sun Nov 03, 2019 10:18 am
- Forum: Octet Exceptions
- Topic: Octet Exceptions
- Replies: 1
- Views: 45
Re: Octet Exceptions
Elements in period three or higher have d-orbitals in their valence shell, meaning that they are able to accommodate additional electrons because they have room to do so.
- Sun Nov 03, 2019 10:15 am
- Forum: Lewis Structures
- Topic: Exceptions to octet rule
- Replies: 4
- Views: 48
Re: Exceptions to octet rule
In lecture he said that atoms in period 3 or higher can accommodate additional electrons because they have d-orbitals, allowing them room to do so. I think breaking the octet rule is done when trying to draw the lewis structure most accurately with the lowest energy or sometimes just to get the righ...
- Sun Nov 03, 2019 10:09 am
- Forum: Bond Lengths & Energies
- Topic: Bond Strength
- Replies: 6
- Views: 87
Re: Bond Strength
When the bond is shorter, the attraction of the electrons to the nucleus becomes stronger. Therefore, a double bond (since it is shorter) will always be stronger than a single bond and a triple bond will always be stronger than a double.
- Sun Nov 03, 2019 8:53 am
- Forum: Lewis Structures
- Topic: Exceptions to the octet rule
- Replies: 3
- Views: 61
Re: Exceptions to the octet rule
How do we know how many valence electrons an element with an expanded octet has? How are lone pairs shown in a lewis dot structure? An element will always have the same number of valence electrons whether it has an expanded octet! Cl can have an expanded octet but its number of valence electrons wi...
- Sun Nov 03, 2019 8:50 am
- Forum: Octet Exceptions
- Topic: Expanded Octets and Formal Charge
- Replies: 3
- Views: 61
Re: Expanded Octets and Formal Charge
For the most part, the central atom will only have an expanded octet because we are trying to get the formal charge to zero. The point is just to draw the best lewis structure so if your formal charge for the central atom isn't zero and it has an expanded octet, I would try to move somethings around...
- Sun Nov 03, 2019 8:44 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Format
- Replies: 4
- Views: 94
Re: Midterm Format
From seeing what Test 1 looked like, I'm pretty sure that the midterm will also be somewhat the same format so I'm assuming all free response.
- Sun Oct 27, 2019 3:42 pm
- Forum: Lewis Structures
- Topic: Lone pair
- Replies: 8
- Views: 131
Re: Lone pair
Lone pairs are just electrons that aren't bonded!
- Sun Oct 27, 2019 3:25 pm
- Forum: Ionic & Covalent Bonds
- Topic: Double and single bond lengths
- Replies: 6
- Views: 59
Re: Double and single bond lengths
A double is shorter than a single bond because it has more electrons and therefore, attracts to the nucleus more, making it stronger. A triple bond is also shorter than a double bond.
- Sun Oct 27, 2019 3:16 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 5
- Views: 123
Re: Formal Charge
We use the formal charge equation to help us find the most stable structure of a molecule.
in FC= V -(L + S/2), V= number of valence electrons, L= number of lone pair electrons, S= number of shared electrons
in FC= V -(L + S/2), V= number of valence electrons, L= number of lone pair electrons, S= number of shared electrons
- Sun Oct 27, 2019 3:13 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Noble gas electron configurations
- Replies: 3
- Views: 68
Re: Noble gas electron configurations
I don't want to say that the textbook is wrong but I'm sure that neon's electron configuration is 1s2 2s2 2p6.
- Sun Oct 27, 2019 3:10 pm
- Forum: Ionic & Covalent Bonds
- Topic: Week 5 HW
- Replies: 4
- Views: 88
Re: Week 5 HW
I would say chemical bonds since that's what we'll be covering in lecture this week.
- Sun Oct 27, 2019 2:46 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: 1E.17
- Replies: 2
- Views: 56
Re: 1E.17
When 4s is not filled, it has lower energy than 3d so it is filled first. But when 3d is filled it is no longer higher in energy, which is why Lavelle wants us to write 4s after 3d. So, when you remove an electron, you would remove it from the closest orbital which would be 4s.
- Fri Oct 25, 2019 12:34 pm
- Forum: Lewis Structures
- Topic: Formal Charges
- Replies: 4
- Views: 59
Re: Formal Charges
Say you want to find the formal charge of S in SO4^-2. You have to draw the lewis structure and from there you'll find the the numbers to plug into the formal charge formula. Number of valence electrons for S is 6. 'L' represents any lone pairs it may have and in this case it has 0. 'S' represents s...
- Sun Oct 20, 2019 11:44 am
- Forum: Administrative Questions and Class Announcements
- Topic: Homework for Week 4
- Replies: 1
- Views: 32
Re: Homework for Week 4
Yes, since we're still covering this topic in class we can do any five problems from the ones he assigned for the quantum world section.
- Sun Oct 20, 2019 11:35 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing Electron Configurations
- Replies: 3
- Views: 31
Re: Writing Electron Configurations
We use those elements because they are noble gasses and aren't reactive, meaning their configuration is complete. 'He' would be 1s2 and 'Ne' would end with 2p6. We use them to help with the configurations of other elements that are further down the periodic table mostly for convenience so we don't h...
- Sat Oct 19, 2019 6:38 pm
- Forum: Limiting Reactant Calculations
- Topic: Missed this Question on Test1
- Replies: 5
- Views: 498
Re: Missed this Question on Test1
First I made sure that the equation was balanced. Then I did the following to find out how much of CO2 and H20 was used to make glucose and therefore figure out what the limiting reagent was. 10.0g CO2 (1mol Co2/ 44.011g CO2) (1mol C6H12O6/ 6mol CO2) (180.156g C6H12O6/ 1 mol C6H12O6) = 6.822g 20.0g ...
- Sat Oct 19, 2019 6:38 pm
- Forum: Limiting Reactant Calculations
- Topic: Missed this Question on Test1
- Replies: 5
- Views: 498
Re: Missed this Question on Test1
First I made sure that the equation was balanced. Then I did the following to find out how much of CO2 and H20 was used to make glucose and therefore figure out what the limiting reagent was. 10.0g CO2 (1mol Co2/ 44.011g CO2) (1mol C6H12O6/ 6mol CO2) (180.156g C6H12O6/ 1 mol C6H12O6) = 6.822g 20.0g ...
- Sat Oct 19, 2019 6:26 pm
- Forum: *Shrodinger Equation
- Topic: Schrodinger Equation
- Replies: 4
- Views: 87
Re: Schrodinger Equation
I believe we use it to help us find the allowed energy levels in a quantum system.