## Search found 103 matches

Sun Mar 15, 2020 8:14 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius eq
Replies: 5
Views: 85

### Re: Arrhenius eq

When you want to know the effect on K with the change in temperature
Sat Mar 14, 2020 11:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Final exam structure
Replies: 2
Views: 144

### Final exam structure

Does anyone know yet if the final will be multiple choice or will be free response?
Sat Mar 14, 2020 12:46 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.5
Replies: 1
Views: 27

### 6N.5

Can someone explain why/how in the answer key it says that since concentration of H+=10^pH, and the given pH is 4, which gives us a concentration of [10^-4]^16 (because the stoichiometric coefficient of H+=16) the end result is [10^66]? Wouldn’t it be [10^64]?
Fri Mar 13, 2020 9:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.1
Replies: 1
Views: 28

### 6M.1

On homework question 6M.1 they are asking us to find the value of E(M2+/M). Im confused because they say we are given a standard Cu(s)|Cu2+ half cell, which I thought was an oxidation but when they give us the formed cell it’s actually on the right making it a reduction.When I look up its standard c...
Thu Mar 12, 2020 10:44 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Homework question 7.1
Replies: 2
Views: 66

### Homework question 7.1

Can someone please explain what the difference and meaning of “kinetic control” and “thermodynamic control”. I am not sure how to use those terms to answer the question they are asking.
Sun Mar 08, 2020 10:56 pm
Forum: General Rate Laws
Topic: 7A.9
Replies: 5
Views: 65

### Re: 7A.9

You first get the concentration by finding the Molar mass of N2O5 which is 108g, you then use the formula C=m/M*V and plug in the values they gave you in the problem.
Sun Mar 08, 2020 10:22 pm
Forum: General Rate Laws
Topic: 7A.15
Replies: 2
Views: 43

### 7A.15

For homework problem 7A.15 how do we know which experiment to divide by? I thought that it was by the experiment with the largest initial rate is this true?
Sun Mar 08, 2020 9:33 pm
Forum: General Rate Laws
Topic: 7A.11 part b
Replies: 1
Views: 29

### 7A.11 part b

Can someone explain how they answered part b to homework 7A.11?
Sun Mar 08, 2020 4:56 pm
Forum: General Rate Laws
Topic: Fractional order and negative orders
Replies: 3
Views: 82

### Fractional order and negative orders

Are we expected to know when to include a product into the rate law?
Sun Mar 08, 2020 4:31 pm
Forum: General Rate Laws
Topic: Ammonia rate of consumption
Replies: 1
Views: 40

### Ammonia rate of consumption

Why is the rate of consumption of NH3 solely equal to kr the (rate constant) and independent of the concentration of NH3?
Sun Mar 01, 2020 10:26 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst equation and ph
Replies: 2
Views: 29

### Nernst equation and ph

How can we derive the ph by using the Nernst equation? Would you have to use log rather than lnQ?
Sun Mar 01, 2020 10:23 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Reducing/oxidizing agent
Replies: 8
Views: 130

### Re: Reducing/oxidizing agent

The reducing agent will be the agent that pretty much causes another substance to reduce so in other words the agent that donates electrons, and the oxidizing agent will be the agent that accepts or gains electrons. I remember it as being the opposite from each other.
Sun Mar 01, 2020 10:20 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Cell Diagram
Replies: 4
Views: 64

### Re: Cell Diagram

Yes it is the same, the right side consist of the reduction reaction (cathode) and the left side consist of the oxidized reaction (anode)
Fri Feb 28, 2020 1:43 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Non-Standard Potential
Replies: 3
Views: 81

### Re: Non-Standard Potential

You can determine if the equilibrium constant of a reaction is greater than or less than one, by plugging all the necessary values into the Nernst equation, by doing this you can isolate lnK to one side in order to find what the value of K is. Usually if the voltage is positive, and the delta G is n...
Fri Feb 28, 2020 1:40 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells
Replies: 6
Views: 85

### Re: Concentration Cells

Both galvanic and concentration cells have a positive voltage, but the difference between both is that in concentration cells contain the same chemical species but in different concentrations, the difference in concentration drives movement of electrons, and the voltage tends to be very low. In galv...
Sun Feb 23, 2020 3:25 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Concentration and cell potential
Replies: 6
Views: 101

### Concentration and cell potential

Can someone please explain how concentration affects cell potential? And how Le Chatelliers principle plays a role in this?
Sun Feb 23, 2020 3:23 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Max cell potential
Replies: 1
Views: 35

### Max cell potential

Why is max cell potential directly related to the free energy difference between reactants and products in cell/redox reaction?
Sun Feb 23, 2020 3:17 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Use of Platinum
Replies: 10
Views: 133

### Re: Use of Platinum

You use platinum when there is no other metal solid being used, platinum is used to conduct these electrons.
Sun Feb 23, 2020 3:11 pm
Forum: Balancing Redox Reactions
Topic: Alkaline reactions
Replies: 2
Views: 25

### Re: Alkaline reactions

The main difference is that when balancing acidic solutions you balance oxygen with water and hydrogen with H+ protons, and in basic solutions you balance oxygen with OH- molecules and balance hydrogen with water.
Sun Feb 23, 2020 3:07 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox reactions
Replies: 4
Views: 50

### Re: Balancing Redox reactions

In acidic solutions you first balance oxygen with water an then balance the hydrogens with protons (H+).
Thu Feb 13, 2020 4:36 pm
Forum: Calculating Work of Expansion
Topic: Positive or negative work
Replies: 15
Views: 299

### Re: Positive or negative work

If you have work being done on the system then work will be positive, and if work is being done by the system then work will be a negative value.
Thu Feb 13, 2020 4:35 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: spontaneity
Replies: 34
Views: 678

### Re: spontaneity

If delta G (Gibbs free energy) is negative then you know that it was spontaneous.
Thu Feb 13, 2020 4:33 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Intensive vs. Extensive
Replies: 15
Views: 342

### Re: Intensive vs. Extensive

Intensive properties do not depend on the quantity of matter , and expensive properties do depend on the amount of matter.
Thu Feb 13, 2020 4:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium concentrations
Replies: 7
Views: 91

### Re: equilibrium concentrations

When calculating equilibrium concentrations we do not include the units in the brackets but concentration is measured using moles/liters.
Thu Feb 13, 2020 4:26 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Curve
Replies: 45
Views: 555

### Re: Midterm Curve

Going off what happened in 14A and in his syllabus, he does not curve the midterm but a 50% in the class is a C, so in that way he does curve the final grade to help those that are close to failing.
Sun Feb 09, 2020 10:44 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: spontaneity
Replies: 18
Views: 168

### Re: spontaneity

It is a spontaneous reaction when delta G is negative, because it means that the free energy of the reactant is higher than the product.
Sun Feb 09, 2020 10:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Material
Replies: 10
Views: 147

### Re: Midterm Material

He mentioned in class that only the first page of outline 4 would be on the midterm.
Sun Feb 09, 2020 10:29 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy calculation
Replies: 3
Views: 56

### Gibbs Free Energy calculation

Will we only be using the Gibbs change in free energy equation? And when do we know to use it instead of just G=H-TS?
Sun Feb 09, 2020 10:12 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Entropy function
Replies: 1
Views: 27

### Entropy function

How Is standard reaction entropy different from the entropy state function? Why is it considered an extensive property?
Sun Feb 09, 2020 10:09 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard reaction enthalpy
Replies: 2
Views: 21

### Standard reaction enthalpy

When you are calculating the standard enthalpy do you only use formation enthalpy or can you use bond enthalpies?
Sun Feb 02, 2020 10:15 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: PLF sessions
Replies: 6
Views: 91

### Re: PLF sessions

Yes you can, you would just have to email that PLF and ask them if you can attend their session :)
Sun Feb 02, 2020 10:13 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Changing the energy of a system
Replies: 9
Views: 62

### Re: Changing the energy of a system

I order to change the energy of a system you can do 3 things
3. Do work on the system
Sun Feb 02, 2020 10:11 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Steam burns
Replies: 8
Views: 79

### Re: Steam burns

Steam releases more energy as opposed to boiling water, the steam releases about 40 kJ of energy.
Sun Feb 02, 2020 9:46 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Negative Enthalpy
Replies: 3
Views: 34

### Negative Enthalpy

Why do things that fo to a lower energy level happen by themselves?
Sun Feb 02, 2020 9:34 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy of isolated system
Replies: 2
Views: 20

### Internal Energy of isolated system

In terms of delta U, why does it remain 0. Why does work + heat equal 0 in isolated systems?
Sun Feb 02, 2020 9:14 pm
Forum: Calculating Work of Expansion
Topic: Constant Pressure
Replies: 3
Views: 35

### Constant Pressure

Under what circumstances should you assume there is a constant pressure?
Sun Jan 26, 2020 9:54 pm
Forum: Phase Changes & Related Calculations
Topic: Focus 4 Homework Questions
Replies: 3
Views: 46

### Re: Focus 4 Homework Questions

Sun Jan 26, 2020 9:53 pm
Forum: Phase Changes & Related Calculations
Topic: Phase changes: endothermic vs exothermic
Replies: 12
Views: 183

### Re: Phase changes: endothermic vs exothermic

Reverse reactions are exothermic because heat is not required, in fact heat is released when going in the reverse reaction.
Sun Jan 26, 2020 9:49 pm
Forum: Phase Changes & Related Calculations
Topic: Work (w)
Replies: 8
Views: 67

### Work (w)

Why is work not a state property and what are different types of work?
Sun Jan 26, 2020 9:48 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy
Replies: 5
Views: 71

### Enthalpy

Why is enthalpy only a state property? Why does the path towards that state not matter?
Sun Jan 26, 2020 6:39 pm
Forum: Phase Changes & Related Calculations
Topic: Why does steam cause burns?
Replies: 29
Views: 274

### Re: Why does steam cause burns?

Steam burns more because if you look at the diagram he showed us in lecture , it releases a lot more energy to go back down to its liquid phase. The release in energy is much more than if you touched boiling hot water.
Thu Jan 16, 2020 11:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Combing kA and kB
Replies: 2
Views: 38

### Combing kA and kB

Can anyone explain why we need to multiply the kA and kB in order the get the Kw for weak acid and base reactions?
Thu Jan 16, 2020 11:15 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas
Replies: 7
Views: 76

### Re: Inert Gas

Inert gases are those gases that do not react, and therefore do not change the reaction, therefore you can use noble gases as an example as they usually do not react with other elements.
Thu Jan 16, 2020 11:13 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Kw
Replies: 16
Views: 135

### Re: Kw

They both essentially mean the same thing, and you can use them interchangeably.
Thu Jan 16, 2020 9:30 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic
Replies: 5
Views: 84

### Exothermic

Why is energy released as new bonds are formed?
Thu Jan 16, 2020 9:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Endothermic vs exothermic
Replies: 4
Views: 51

### Endothermic vs exothermic

Can someone please explain why : 1. If a reaction requires Heat, (is endothermic) while forming products, then heating will favor P (product) formation when additional heat is used. 2. If a reaction gives off heat, (is exothermic) while forming products, then heating will favor R formation when addi...
Sun Jan 12, 2020 10:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K
Replies: 10
Views: 74

### Re: K

Kc is the equilibrium constant used for aqueous solutions, because they have concentration values. Kp is the equilibrium constant for gases, since they have partial pressures.
Thu Jan 09, 2020 4:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.11
Replies: 4
Views: 50

### 5G.11

For question 5G.11 it asks to write the reaction quotient for the reactions given. I know that to calculate the Q you do the same thing as when you are calculating for K, but in the answer key it states that the Q= 1/(PBCl3)^2.
Why would it not be (PB2Cl4)(PHg2Cl2)/(Pcl3)^2(PHg)^2?
Thu Jan 09, 2020 2:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G. 3
Replies: 5
Views: 59

### Re: 5G. 3

Because it contains aqueous solution we would use Kc instead of Kp which is just for gases.
Thu Jan 09, 2020 2:25 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q vs K
Replies: 8
Views: 81

### Re: Q vs K

Q is not at equilibrium, it is just products over reactants at any given time during the reaction. K is the equilibrium constant of the products over her reactants.
Thu Jan 09, 2020 2:22 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Re: Q and Ke: Small K value and Large K value
Replies: 7
Views: 60

### Re: Q and Ke: Small K value and Large K value

The reaction quotient is the amount of products over reactants at any time during the Rxn, it is calculated the same way as K but it is not at equilibrium.
Sun Dec 08, 2019 7:41 pm
Forum: Student Social/Study Group
Replies: 44
Views: 2161

I hope this is true! But yeah I have heard that his final grades are curved but test aren’t.
Sun Dec 08, 2019 12:26 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ph and poH of weak acids
Replies: 8
Views: 96

### Ph and poH of weak acids

Will we be asked to measure the ph and PoH of weak acids and bases?
Sun Dec 08, 2019 12:25 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: CO2 in blood
Replies: 1
Views: 41

### CO2 in blood

So if there is a lot of co2 in the blood it will cause there to be more carbonic acid in the blood which in turn creates more H30+ molecules increasing the pH?
Sat Dec 07, 2019 4:20 pm
Forum: Identifying Acidic & Basic Salts
Topic: Titration
Replies: 1
Views: 49

### Titration

Does anyone know what we will have to know about titrations? Or will that not be on the final?
Sat Dec 07, 2019 4:18 pm
Forum: Identifying Acidic & Basic Salts
Topic: 6D.11
Replies: 1
Views: 48

### 6D.11

For part a in 6D. 11 it asks whether an aqueous solution of each of the following salts has a pH equal to, greater than or less than 7. How would you determine this?
Sun Dec 01, 2019 11:02 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acting as a base
Replies: 1
Views: 50

### Acting as a base

Can any biological compound with a lone pair act as a base? Or is this only true for Nitrogen?
Sun Dec 01, 2019 11:00 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Use of Bronsted or Lewis Definitions
Replies: 7
Views: 90

### Re: Use of Bronsted or Lewis Definitions

You can use either one, but for now I would use the bronsted definition as it mentions protons which is what we are focusing on in this section.
Sun Dec 01, 2019 10:58 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Amphoteric compounds
Replies: 4
Views: 69

### Amphoteric compounds

What are amphoteric compounds and why are they important? Would h20 be considered an amphoteric compound?
Sun Dec 01, 2019 10:56 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Difference between weak acids/bases and strong acids/bases
Replies: 6
Views: 100

### Re: Difference between weak acids/bases and strong acids/bases

Strong acids and bases will fully ionize and disassociate while weak acids and bases will not fully ionize. Strong acids will produce more photons in solutions than weak acids.
Sun Dec 01, 2019 10:54 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acids Vs. Bases
Replies: 11
Views: 174

### Re: Acids Vs. Bases

I like to remember that if it is an acid it will donate protons, it is a proton donator. If it is a base it will be a proton acceptor.
Sun Nov 24, 2019 10:52 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition metals
Replies: 1
Views: 37

### Transition metals

Are only transition metals in the d block able to form ligand complexes?
Sun Nov 24, 2019 10:49 pm
Forum: Naming
Topic: Trans and Cis
Replies: 8
Views: 163

### Re: Trans and Cis

Yes, whenever you see that there are the same two molecules on the same side you will know it is cis, and if you see them on opposite sides it is trans.
Sun Nov 24, 2019 10:43 pm
Forum: Hybridization
Topic: Shapes
Replies: 3
Views: 50

### Re: Shapes

Specific shapes will tell you the amount of electronic density that is found. For example for Tetrahedral you have 4 regions of electron density regions, which means there will be 4 hybridization orbitals which is sp3.
Sun Nov 24, 2019 10:39 pm
Forum: Hybridization
Topic: sigma or pi?
Replies: 20
Views: 323

### Re: sigma or pi?

Whenever you see a single bond know that it is sigma. When you see a double or triple bond one will be sigma and the other two will be pi bonds. Sigma bonds are single covalent bonds.
Sun Nov 24, 2019 10:38 pm
Forum: Hybridization
Topic: Hybridization number
Replies: 3
Views: 53

### Hybridization number

Will the hybridization orbitals always be equal to the number of electronic density regions? If yes, why?
Thu Nov 21, 2019 9:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Week 8 homework
Replies: 2
Views: 83

### Week 8 homework

Does anyone know if we can turn in homework this week on molecular structures since we have the test 2 on it this week?
Sun Nov 17, 2019 10:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double and triple bonds
Replies: 4
Views: 67

### Double and triple bonds

I know that double and triple bonds are not considered double or triple regions of electron density, but why? Why do we not count them as such?
Sun Nov 17, 2019 10:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 7
Views: 109

### Re: Bond Angles

Due to lone pair repulsion, the more lone pairs there are the more repulsion there will be.
Sun Nov 17, 2019 10:33 pm
Forum: Hybridization
Topic: Test 2
Replies: 11
Views: 145

### Re: Test 2

Dr. Lavelle mentioned in lecture that test 2 will not include hybridization.
Sun Nov 17, 2019 10:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 3
Views: 37

### Re: Molecular Shape

When you have 5 regions of electron density your electronic shape is Trigonal bipyramid, such as BrF3, but since in those regions two of those are lone pairs the molecular shape will be T shape. As for NH3, your regions of electronic density is 4 giving it an electronic shape of a tetrahedral, and s...
Sun Nov 17, 2019 10:07 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E21 part d
Replies: 1
Views: 26

### Re: 2E21 part d

In my discussion my TA said that it is sufficient to just write that the bond angles are less than 109.
Sun Nov 10, 2019 6:46 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: Structure and bond type
Replies: 2
Views: 34

### Structure and bond type

By just looking at a Lewis structure how can we distinguish the type of bond and dipole moment present?
Sun Nov 10, 2019 6:44 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: Surface Area
Replies: 2
Views: 29

### Surface Area

How does more surface area influence strength of bonds and boiling point?
Sun Nov 10, 2019 6:25 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: Boiling point
Replies: 5
Views: 94

### Boiling point

How does a molecules bond type relate to its boiling point? Which types of bonds will cause higher or lower boiling points?
Sun Nov 10, 2019 6:17 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization of Nitrogen vs Oxygen
Replies: 11
Views: 177

### Re: Ionization of Nitrogen vs Oxygen

Due to Nitrogen’s half filled orbitals, it makes it more stable and more difficult to remove and electron as opposed to oxygen which has two paired electrons.
Sun Nov 03, 2019 8:19 pm
Forum: Electronegativity
Topic: which bond
Replies: 4
Views: 88

### Re: which bond

If the electronegativity difference between the two elements is greater than or equal to 2.5 then it is a ionic bond, if the difference is equal to or below 1.5 it is a covalent bond. Basically the greater the difference in electronegativity the more pull on electrons one element will have over the ...
Sun Nov 03, 2019 8:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: isoelectronic definition
Replies: 7
Views: 100

### Re: isoelectronic definition

Isoelectric refers to elements that have the same amount of electrons, but have very different chemical characteristics.
Sun Nov 03, 2019 8:09 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What are the octet exceptions?
Replies: 11
Views: 130

### Re: What are the octet exceptions?

Octet exceptions are the first 4 elements in the periodic table which are; H,He,Li, and Be, as they will never have a full octet. An exception to this octet guideline are all elements after Neon, so in the 3p block and on, these elements are allowed to have more than 8 electrons, they don’t have to ...
Sun Nov 03, 2019 8:06 pm
Forum: Lewis Structures
Topic: Which element at center of the structure
Replies: 6
Views: 114

### Re: Which element at center of the structure

The element with the lowest ionization energy will always be in the middle, but hydrogen will never be in the middle. Just look at your periodic table and remember that the ionization energy increases as you go across the periodic table (left to right)
Sun Nov 03, 2019 8:04 pm
Forum: Lewis Structures
Topic: Resonance Structure
Replies: 4
Views: 59

### Re: Resonance Structure

If asked for a Lewis structure for an element with multiple variations (resonance) you have to include the resonance structures and indicate that there is a hybridization of the the structure, which will be a a combination of the resonance structures. To be safe I would always include it.
Sun Oct 27, 2019 7:41 pm
Forum: Trends in The Periodic Table
Topic: Electron affinity equation
Replies: 1
Views: 37

### Electron affinity equation

Can someone explain why in order to find the electron affinity, you need to subtract the energy of the neutral atom from the energy of the final. Thank you.
Sun Oct 27, 2019 7:38 pm
Forum: Ionic & Covalent Bonds
Topic: Writing Electron Configurations for an Ion
Replies: 6
Views: 81

### Re: Writing Electron Configurations for an Ion

When writing the electron configuration of an ion, it changes from that of its parent element because you are changing the number of electrons in the element. When writing the change configuration you have to look at the charge of the ion, if its a positive charge it means that electrons were remove...
Sun Oct 27, 2019 7:34 pm
Forum: Lewis Structures
Topic: Clarification
Replies: 6
Views: 81

### Re: Clarification

In the lecture Professor Lavelle states that obtaining a formal charge of 0 is much more important than following the octet rule.
Sun Oct 27, 2019 7:32 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance
Replies: 10
Views: 126

### Re: Resonance

Resonance just means you can write a Lewis structure in different ways, you can write bonds in different ways, but it is still the same molecule.
Sun Oct 27, 2019 7:30 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 11
Views: 144

### Re: Covalent Bonds

Covalent bonds can only be formed by nonmetals, and metals are more likely to form ionic bonds. Remember that metals often times become cations because it is easier for them to give up electrons. Non metals have high ionization energy.
Sun Oct 20, 2019 12:06 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Replies: 5
Views: 56

Since there was a question in the homework which asked to name the types of light/radiation from highest to lowest energy, I am assuming we will be tested on it and expected to memorize them, that would be my safest guess.
Sun Oct 20, 2019 12:02 am
Forum: Properties of Light
Topic: Unit for Wavelength
Replies: 34
Views: 420

### Re: Unit for Wavelength

It is measured in meters, it is a distance. You can give it in picometers, and nanometers as well.
Sat Oct 19, 2019 11:44 pm
Forum: Photoelectric Effect
Topic: One photon one atom interaction
Replies: 14
Views: 226

### Re: One photon one atom interaction

After increasing the frequency and the threshold of the electrons being met, in order to have more electrons being ejected you can then increase the intensity as it produces more photons at this energy, which increases photon, electron interactions. But remember that this will not change the amount ...
Sat Oct 19, 2019 11:41 pm
Forum: Photoelectric Effect
Topic: Intensity of Light
Replies: 5
Views: 90

### Re: Intensity of Light

When you increase the intensity of light you are only increasing the number of photons being emitted, this does not increase the energy that each photon emits. In order to have electrons be released from metal, the energy of each individual photon must be high enough to pass the energy threshold and...
Sat Oct 19, 2019 11:39 pm
Forum: Properties of Light
Topic: 1A.9 Energy of Photon
Replies: 12
Views: 155

### Re: 1A.9 Energy of Photon

After you find the wavelength of the radiation, you then find the energy by using E=h*v, which is Plancks constant 6.626x10^-34J times frequency which is given. Hope this helps!
Sat Oct 19, 2019 11:35 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Spin up and spin down
Replies: 13
Views: 202

### Spin up and spin down

I am having a hard time understanding the concept of different spin states in electrons, I never learned this in High school chem. Can anyone explain how we know if an electron is in a spin up or spin down state?
Sat Oct 19, 2019 11:27 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron States
Replies: 3
Views: 53

### Electron States

What did Professor Lavelle mean when he said that an electron is in a particular state, not in a specific orbital? I am having a hard time understanding this concept.
Sat Oct 12, 2019 10:42 pm
Forum: Properties of Electrons
Topic: Electron Energy Levels
Replies: 8
Views: 79

### Re: Electron Energy Levels

From what I recall Professor Lavelle saying is that each atom has unique electronic structures and energy levels, which is why they can only absorb or emit unique frequencies that are allowed by their unique structures.
Sat Oct 12, 2019 10:37 pm
Forum: Photoelectric Effect
Topic: Wave-like Properties
Replies: 4
Views: 71

### Re: Wave-like Properties

What I got from lecture was that the larger the mass the smaller the wavelength properties making it not detectable. So anything less that 10^-15m does not have detestable wavelength properties.
Sat Oct 12, 2019 10:35 pm
Forum: Photoelectric Effect
Topic: 1B.7 part b
Replies: 1
Views: 38

### Re: 1B.7 part b

For part b you are asked to find the energy emitted by 5 mg of Sodium atoms. You first have to find the number of moles in 5mg of Na, you then take this number and calculate the energy by multiplying the number of moles in 5mg of Na by Avogrado’s constant over 1 mole, you then multiple that by what ...
Sat Oct 12, 2019 10:26 pm
Forum: Photoelectric Effect
Topic: Classic Wave in Photoelectric effect
Replies: 5
Views: 95

### Classic Wave in Photoelectric effect

Why does does the the model equation Ek=1/2Me-ve^2 not change when you increase intensity? How is this different from the wave model?
Sat Oct 12, 2019 9:58 pm
Forum: Photoelectric Effect
Topic: Removing electrons in Photoelectric concept
Replies: 2
Views: 24

### Removing electrons in Photoelectric concept

In lecture we went over the photoelectric effect, and I understood that if an incoming photon does not have the energy needed to remove an electron, and electron won’t be ejected. My question is what is that threshold that the photon should hit? What energy level are we comparing it to and why?
Wed Oct 02, 2019 11:20 pm
Forum: Empirical & Molecular Formulas
Topic: Clarification on the Vitamin C Example
Replies: 6
Views: 124

### Re: Clarification on the Vitamin C Example

I believe this was because we are supposed to round up.
Wed Oct 02, 2019 11:18 pm
Forum: Empirical & Molecular Formulas
Topic: HW 1 Problem F.9
Replies: 7
Views: 225

### Re: HW 1 Problem F.9

Yes, the empirical formula is the ratio of elements, unlike the molecular formula which gives you the exact numbers of elements in a compound.