## Search found 100 matches

Wed Mar 11, 2020 3:31 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 3
Views: 45

### Re: Catalysts

You can tell what is an intermediate when it's not originally in the reaction as a reactant, but then is formed, just to be used up in the next reaction (won't be seen as the final product either). Catalysts can be found as a product after being used as a reactant.
Wed Mar 11, 2020 3:27 pm
Forum: Second Order Reactions
Topic: Zeroth, First, Second Orders
Replies: 4
Views: 90

### Re: Zeroth, First, Second Orders

Zeroth order means a reaction with a rate that is independent of concentration of reactant. A catalyst or enzyme is required for this type of reaction. First order means a reaction in which rate is proportional to the first power of the molar concentration of a substance. Second order means a reacti...
Wed Mar 11, 2020 3:24 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: rate constant
Replies: 5
Views: 65

### Re: rate constant

The rate constant is affected by the temperature and catalysts in the reaction.
Wed Mar 11, 2020 3:22 pm
Forum: Student Social/Study Group
Topic: discussion
Replies: 3
Views: 155

### Re: discussion

It depends on your TA- they probably sent out an email about it. My TA is posting her notes on what we were going to be going over.
Wed Mar 11, 2020 3:21 pm
Forum: General Rate Laws
Topic: Rate limiting step
Replies: 13
Views: 162

### Re: Rate limiting step

The rate-limiting step is the slowest step of the reaction. You'll be using the rate law of the rate-limiting step as the overall rate.
Wed Mar 04, 2020 2:47 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell diagram order of phases
Replies: 6
Views: 136

### Re: cell diagram order of phases

I was always told to follow (s)|(g)|(aq)||(aq)|(g)|(s). Aqueous in the middle separated by two || (salt bridge), and the solids on the outside.
Wed Mar 04, 2020 2:45 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free and Direction of Reaction
Replies: 3
Views: 65

### Re: Gibbs Free and Direction of Reaction

When Gibbs Free Energy is negative, it is spontaneous. When it's positive, it will produce more reactants, because it will not occur as easily as it would with spontaneous reactions.
Wed Mar 04, 2020 2:41 am
Forum: Balancing Redox Reactions
Topic: Balancing Redox reactions
Replies: 4
Views: 70

### Re: Balancing Redox reactions

1. Separate the half reactions 2. Balance all of the elements that aren't oxygen or hydrogen 3. Add H2O to balance oxygen 4. Add protons (H+) to balance hydrogen 5. Balance charge of each equation with electrons 6. Scale the equations so that the amount of electrons are equal on both sides 7. Add th...
Wed Mar 04, 2020 2:38 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Units for G°
Replies: 6
Views: 57

### Re: Units for G°

I also think it's joules per mole, but I guess to be safe, just make sure to include all units when calculating and then seeing what cancels out in the end for the final units.
Wed Mar 04, 2020 2:27 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt(s)
Replies: 3
Views: 46

### Re: Pt(s)

If neither of the species is a solid or if the solid is a poor conductor, you can just add Pt(s) to it (solids will always be on the outside of cell diagrams). An example would be: Fe3+(aq) + Cu(s) -> Cu2+(aq) + Fe2+(aq). After balancing the reaction, you will notice that there are no solids on the ...
Tue Feb 25, 2020 10:24 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: log and ln in Nernst
Replies: 8
Views: 85

### Re: log and ln in Nernst

They're basically the same thing for the Nerst equation:
E=Eo-(RT/nF)lnQ
E=Eo-(2.303RT/nF)logQ
This is because lnx=2.303logx
Tue Feb 25, 2020 10:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cathode vs Anode
Replies: 6
Views: 113

### Re: Cathode vs Anode

At the anode, it's where oxidation happens, so there'll be a loss of electrons. On the other hand, at the cathode, there's a gain of electrons because that's where reduction occurs.
Tue Feb 25, 2020 10:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode and Cathode
Replies: 4
Views: 53

### Re: Anode and Cathode

Anode is where oxidation happens, which is the loss of electrons, whereas the cathode is where reduction occurs, which is gain of electrons (easy to memorize through An Ox and Red Cat!). Because electrons will flow to the more positive side, the electrons will flow from the anode to cathode.
Tue Feb 25, 2020 10:01 pm
Forum: Balancing Redox Reactions
Topic: redox reactions
Replies: 5
Views: 61

### Re: redox reactions

You can remember which is reduction and which one is oxidation through mnemonics, such as OIL RIG (Oxidation is Losing electrons, Reduction is Gaining electrons). You can also just see it in the actual equation: reduction is when the oxidation number is reduced
Tue Feb 25, 2020 9:59 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free energy units
Replies: 4
Views: 99

### Re: Gibbs Free energy units

I'm pretty sure the units can be either or, but you just have to make sure your units are consistent throughout your entire calculation or then you'll have answers of different degrees.
Wed Feb 19, 2020 2:13 am
Forum: Balancing Redox Reactions
Topic: Oxidation Number Rules
Replies: 7
Views: 141

### Re: Oxidation Number Rules

I think it'd be best to memorize most of them so that when you're working with the half reactions, it'll be easier to calculate and solve.
Wed Feb 19, 2020 2:07 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Replies: 11
Views: 221

There is no transfer of heat, so q will equal 0.
Wed Feb 19, 2020 1:57 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Spontaneous
Replies: 10
Views: 246

### Re: Spontaneous

In order to determine spontaneity based on Gibbs Free Energy:
ΔG∘<0 = spontaneous
ΔG∘<0 = not spontaneous
Wed Feb 19, 2020 1:55 am
Forum: Balancing Redox Reactions
Topic: Half Reactions
Replies: 7
Views: 63

### Re: Half Reactions

You split the reaction in half so that you can easily notice how many H+ and H2Os you'll need in order to balance the equation, plus the electrons. There should be the same amount of each on both sides after balancing.
Wed Feb 19, 2020 1:48 am
Forum: Balancing Redox Reactions
Topic: Balancing half reactions
Replies: 11
Views: 112

### Re: Balancing half reactions

When you combine the two half reactions together, the electrons on both sides should cancel each other out, so make sure that they're equal to one another before combining.
Thu Feb 13, 2020 4:36 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: State Functions
Replies: 4
Views: 160

### Re: State Functions

When I'm under Pressure and feeling Dense, all I want to do is watch TV and get HUGS.
P= pressure
D= density
T= temperature
V= volume
H= enthalpy
U= internal energy
G= Gibbs Free Energy
S= entropy
Thu Feb 13, 2020 4:33 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: spontaneity
Replies: 34
Views: 678

### Re: spontaneity

Gibbs Free Energy (delta G) gives information about the spontaneity of a reaction. If deltaG<0, then the reaction is spontaneous.
Thu Feb 13, 2020 4:31 pm
Forum: Calculating Work of Expansion
Topic: Positive or negative work
Replies: 15
Views: 299

### Re: Positive or negative work

Work is negative if the system does work on surroundings, while being positive if the surroundings do work on the system.
Thu Feb 13, 2020 4:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess Law
Replies: 6
Views: 93

### Re: Hess Law

For Hess's Law, you need to get the total sum of the entropies/enthalpies/Gibbs Free Energy (only because they're state functions/extensive properties) of the products and then subtract from it the total sum of the reactants. Don't forget to include the coefficients.
Thu Feb 13, 2020 4:25 pm
Forum: Calculating Work of Expansion
Topic: Work
Replies: 5
Views: 80

### Re: Work

When it's irreversible, the equation for work is w=-Pex*deltaV or -deltan*R*T. When it's reversible, the equation is w=-n*R*T*ln(vf/vi).
Wed Feb 05, 2020 9:48 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Equation for q
Replies: 4
Views: 42

### Re: Equation for q

The first one is dealing with the molar heat capacity (indicated by the n variable), while the second one is used with specific heat capacity.
Wed Feb 05, 2020 9:45 am
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: Calculating W
Replies: 3
Views: 37

### Re: Calculating W

When you remove ln2 from both sides, it's just multiplying Avogadro's number(NA) with Boltzmann's constant (kB) to equal the gas constant (R). R depends on which units you are using in the problem, but typically is 8.314 J/mol*K.
Wed Feb 05, 2020 9:41 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Reversible vs Irreversible
Replies: 4
Views: 31

### Re: Reversible vs Irreversible

In addition to when Kc is between 10^-3 and 10^3, when discussing isothermal expansions, it's reversible when the reaction is gradual, rather than sudden (as seen through the two different work formulas).
Wed Feb 05, 2020 9:39 am
Forum: Calculating Work of Expansion
Topic: Work on a system +/-
Replies: 4
Views: 41

### Re: Work on a system +/-

Work is negative if the system does work on surroundings; the system's internal energy decreases and energy is lost.
Work is positive is the surroundings does work on the system; the internal energy of the system increases.
Wed Feb 05, 2020 9:33 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cv and Cp
Replies: 3
Views: 33

### Re: Cv and Cp

When heat is added under constant pressure, the substance expands and does work, whereas when heat is added under a constant volume, no work is done.
Tue Jan 28, 2020 10:36 pm
Forum: Ideal Gases
Topic: Ideal Gas
Replies: 4
Views: 59

### Re: Ideal Gas

The only interaction between ideal gas molecules would be elastic collisions upon impacts with each other or an elastic collision with walls of a container. Ideal gas molecules have no volume in and of themselves.
Tue Jan 28, 2020 10:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta U
Replies: 6
Views: 59

### Re: Delta U

delta U is the change in internal energy
You calculate it with delta U = q+w, where q = heat and w = work.
Tue Jan 28, 2020 10:33 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: q vs deltaH
Replies: 6
Views: 68

### Re: q vs deltaH

JChen_2I wrote:Could someone explain the difference between q and deltaH please? Thank you!

q= transfer of thermal energy from hot to cold objects until thermal equilibrium is reached
delta H = change in heat energy
Tue Jan 28, 2020 10:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Calculating Work
Replies: 3
Views: 42

### Re: Calculating Work

Irreversible expansion (sudden isothermal expansion) is calculated: w=-Pex(deltaV)
Reversible expansion (gradual isothermal expansion) is calculated: w=-nRT * ln(vf/vi)
Tue Jan 28, 2020 9:49 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Heat Supplied to a system
Replies: 6
Views: 104

### Re: Heat Supplied to a system

Are Cs and Cm both constants? Can I chose to use Kelvin or Celcius or do I need to use a certain unit unit of measurement in the measurement for specific head of the heat equation. Lavelle mentioned in class that we should be choosing Kelvin for the most part whenever we're calculating. However, ma...
Mon Jan 20, 2020 3:59 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure changes
Replies: 5
Views: 32

### Re: Pressure changes

Changes due to pressure will only occur when there are a difference in moles per side of reaction.
Mon Jan 20, 2020 3:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw temperature
Replies: 8
Views: 57

### Re: Kw temperature

Jessica Esparza 2H wrote:Does anyone know how this number would change in response to temperature?

As the temperature increases, the equilibrium moves further to the right hand side which leads Kw to get larger
Mon Jan 20, 2020 3:56 pm
Forum: Ideal Gases
Topic: Ideal Gases: Most Ideal
Replies: 3
Views: 48

### Re: Ideal Gases: Most Ideal

Helium would be the closest to the most ideal gas, because it exists as a single atom, which makes the Van der Waals dispersion forces as low as possible.
Mon Jan 20, 2020 3:51 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Kc vs K
Replies: 7
Views: 80

### Re: Kc vs K

So when do we use K and when do we use Kc? When will we need to convert and how do we convert it? You use Kc when dealing with molar concentrations when you're figuring out the equilibrium constant. You don't really convert between K and Kc, because as the previous answer stated, Kc is basically a ...
Mon Jan 20, 2020 3:49 pm
Forum: Ideal Gases
Topic: R constant for PV=nRT
Replies: 7
Views: 59

### Re: R constant for PV=nRT

R value is a constant and is chosen based on which unit is given in the problem. Make sure to keep an eye out for the unit so that you know which R value to use!
Wed Jan 15, 2020 2:46 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant
Replies: 4
Views: 40

### Re: Equilibrium Constant

Solids and liquids are always excluded when calculating the equilibrium constant, not aqueous though.
Wed Jan 15, 2020 2:45 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What is K
Replies: 6
Views: 71

### Re: What is K

K is just equilibrium constant (also referred to as Keq). Kc refers to when you're using aqueous reactants/products, whereas you'd use Kp for gaseous reactions.
Wed Jan 15, 2020 2:43 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K units
Replies: 10
Views: 117

### Re: K units

K is a unitless quantity, because it's just a ratio of product over reactants. This also goes into the concept of activities (but that hasn't been really gone over in depth yet)
Wed Jan 15, 2020 2:38 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium concentration with gases
Replies: 7
Views: 77

### Re: equilibrium concentration with gases

If moles of the reactants and products are included in the problem, then you'll just assume that pressure is ignored. You'd know partial pressure if the unit given is atm.
Wed Jan 15, 2020 2:37 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient Units
Replies: 10
Views: 84

### Re: Reaction Quotient Units

Normally, whether or not it is mentioned in the problem, Q is unitless.
Mon Jan 13, 2020 1:23 am
Forum: Ideal Gases
Topic: ICE Table
Replies: 9
Views: 105

### Re: ICE Table

Alison Trinh 1E wrote:What is an ICE table?

ICE tables are composed of the concentrations of molecules in solution in different stages of a reaction, and are usually used to calculate the K of a reaction.
Mon Jan 13, 2020 1:19 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Chatelier's Principle
Replies: 7
Views: 71

### Re: Chatelier's Principle

Le Chatelier's Principle states that chemical reactions adjust so as to minimize the effect of changes. You normally use this for when changes occur to the reaction.
Mon Jan 13, 2020 1:13 am
Forum: Ideal Gases
Topic: partial pressures
Replies: 7
Views: 76

### Re: partial pressures

The ratio represented the equilibrium constant K, so it'll remain the same.
Mon Jan 13, 2020 1:00 am
Forum: Ideal Gases
Topic: pv = nRT purpose
Replies: 5
Views: 57

### Re: pv = nRT purpose

This is the ideal gas law; you would use this equation when you're given three of the four properties of a gas: pressure, volume, number of moles, and temperature.
Mon Jan 13, 2020 12:53 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction shifts right or left?
Replies: 14
Views: 224

### Re: Reaction shifts right or left?

Reaction is shifted to the left: the forward reaction is favored (reactants).
Reaction is shifted to the right: the reverse reaction is favored (products).
Tue Dec 03, 2019 1:31 pm
Forum: Naming
Topic: Naming Coordination Compounds
Replies: 5
Views: 50

### Re: Naming Coordination Compounds

I was told by a few other people that it's recommend to try to memorize them.
Tue Dec 03, 2019 1:23 pm
Forum: Lewis Acids & Bases
Topic: diff b/w lewis acid and base
Replies: 12
Views: 197

### Re: diff b/w lewis acid and base

Lewis acids: accept an electron pair
Lewis bases: donate a pair of electrons
Tue Dec 03, 2019 1:11 pm
Forum: Student Social/Study Group
Topic: Final topics
Replies: 10
Views: 120

### Re: Final topics

The final is going to be cumulative, but there will be a bigger emphasis on the later lessons.
Tue Dec 03, 2019 1:08 pm
Forum: Student Social/Study Group
Topic: Final topics
Replies: 10
Views: 120

### Re: Final topics

The final is going to be cumulative, but there will be a bigger emphasis on the later lessons.
Tue Dec 03, 2019 12:41 pm
Forum: Naming
Topic: Table 9C.1
Replies: 6
Views: 111

### Re: Table 9C.1

Maya Beal Dis 1E wrote:Do we need to have the full name of edta memorized or can we just remember the abreviation?

I was told by other people that it's highly recommended to memorize the full name
Wed Nov 27, 2019 9:28 pm
Forum: Lewis Acids & Bases
Topic: Proton acceptor and proton donor?
Replies: 33
Views: 441

### Re: Proton acceptor and proton donor?

Acids: proton donors
Bases: proton acceptors
These terms are more directly related to Bronsted-Lowry descriptions.
Wed Nov 27, 2019 9:15 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: How to take the log to get the pH?
Replies: 8
Views: 87

### Re: How to take the log to get the pH?

BeylemZ-4A wrote:would a really weak base be close to 7? or as far away from 7 as possible?

for example:
would a pH of 8 be more or less basic than a pH of 12?

A pH of 8 would be less basic than a pH of 12. A really weak base would be as far away from 14.
Wed Nov 27, 2019 9:06 pm
Forum: Lewis Acids & Bases
Topic: Difference between Bronsted and Lewis Acid?
Replies: 6
Views: 81

### Re: Difference between Bronsted and Lewis Acid?

Bronsted-Lowry acid: donates a proton
Lewis acid: accepts an electron pair from a donor compound
Wed Nov 27, 2019 9:00 pm
Forum: Lewis Acids & Bases
Topic: What is the correct definition of a base?
Replies: 5
Views: 81

### Re: What is the correct definition of a base?

A base are substances that, in aqueous solution, release hydroxide (OH−) ions.
A Lewis base can donate a pair of nonbonding electrons.
Wed Nov 27, 2019 8:57 pm
Forum: Hybridization
Topic: Sigma and Pi Bonds
Replies: 21
Views: 184

### Re: Sigma and Pi Bonds

Single bonds are sigma bond, all double bonds have 1 sigma bond and 1 pi bond, and every triple bond has 1 sigma bond and 2 pi bonds.
Sun Nov 24, 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: Dipole-Dipole
Replies: 2
Views: 51

### Re: Dipole-Dipole

A dipole-dipole force occurs between two polar molecules (positive end of one polar molecule and the negative end of another polar molecule).
Sun Nov 24, 2019 11:22 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Ions
Replies: 3
Views: 162

### Re: Ions

An ion is a charged atom or molecule that has gained or lost one or more of its valence electrons. So then, I believe all elements are able to be ions. Were you possibly asking about ionic bonds?
Sun Nov 24, 2019 11:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shape
Replies: 21
Views: 417

### Re: T-shape

T-shape is a molecular geometry that occurs with 3 bonds and 2 lone pairs around the central atom in the molecule
Thu Nov 21, 2019 1:16 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: Strongest force
Replies: 6
Views: 60

### Re: Strongest force

From TA's notes: ion-ion > ion-dipole > hydrogen bond(strong dipole) > dipole-dipole > dipole-induced dipole > induced dipole-induced dipole
Wed Nov 20, 2019 6:27 pm
Forum: Sigma & Pi Bonds
Topic: Why are sigma bonds stronger than pi bonds?
Replies: 6
Views: 100

### Re: Why are sigma bonds stronger than pi bonds?

To add onto the previous comments, the greater the extent of overlapping, the higher the probability of finding the valence electrons in between the nuclei and hence the bond will be stronger and shorter.
Fri Nov 15, 2019 1:59 am
Forum: Trends in The Periodic Table
Topic: Question
Replies: 17
Views: 605

### Re: Question

Electronegativity is an atom's ability to attract and bind with electrons, while ionization energy is the energy required to remove an electron from a neutral atom in its gaseous phase. They have the same trend because if the ionization energy of an atom is high, the atom is more reluctant in giving...
Fri Nov 15, 2019 1:49 am
Forum: Lewis Structures
Topic: Lewis Structure
Replies: 6
Views: 86

### Re: Lewis Structure

To show a lewis structure at its lowest energy, you'll need to calculate the formal charges and make sure that it's equal to zero or as close as you can. You'll use the formula FC=V-(B+d) for each of the elements. V is valence electrons, B is bonds, and d is dots :)
Thu Nov 14, 2019 10:36 pm
Forum: Electronegativity
Topic: Increasing/Decreasing Electronegativity
Replies: 14
Views: 240

### Re: Increasing/Decreasing Electronegativity

From left to right across a period of elements, electronegativity increases. If the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one. Similarly, if the valence shell is more than half full, it is easier to pull an electron into the valence...
Thu Nov 14, 2019 10:33 pm
Forum: Resonance Structures
Topic: Explanation of bonds
Replies: 3
Views: 48

### Re: Explanation of bonds

I think you should mention how the additional electrons attract the nuclei more strongly which pulls the atoms closer together, thus creating a stronger and shorter bond.
Thu Nov 14, 2019 3:38 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: 2D. 11
Replies: 2
Views: 129

### Re: 2D. 11

Generally, polarizability increases as the volume occupied by electrons increases. On rows of the periodic table, polarizability therefore decreases from left to right, and it increases down on columns of the periodic table. You can also divide it between anions and cations. Anions that are large ar...
Fri Nov 08, 2019 12:34 pm
Forum: Bond Lengths & Energies
Topic: Bond Lengths
Replies: 8
Views: 162

### Re: Bond Lengths

Because of attractive forces, double and triple bonds are shorter than the single bonds because they pull the atoms closer than the weak single bond.
Fri Nov 08, 2019 12:31 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Strength of Cations
Replies: 8
Views: 77

### Re: Polarizing Strength of Cations

A cation can be expected to have high polarizing power if it is small and highly charged. A small radius means that the center of charge of a highly charged cation can get very close to anion, where it can exert a strong pull on the anion's electrons. You can read more about this in 2D.2 in the text...
Fri Nov 08, 2019 12:27 pm
Forum: Trends in The Periodic Table
Topic: electronegativity trend
Replies: 3
Views: 149

### Re: electronegativity trend

For across a period: if the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one. Similarly, if the valence shell is more than half full, it is easier to pull an electron into the valence shell than to donate one. From top to bottom down a gro...
Fri Nov 08, 2019 12:12 pm
Forum: Octet Exceptions
Topic: Lewis Acids and Bases?
Replies: 11
Views: 159

### Re: Lewis Acids and Bases?

Lewis acid is an electron pair acceptor, while Lewis base donates nonbonding electrons. The bond in which both electrons come from one of the atoms is called a coordinate covalent bond. You can find this information in 2C.3 in the textbook.
Fri Nov 08, 2019 12:06 pm
Forum: Quantum Numbers and The H-Atom
Topic: n, l ,ml, ms
Replies: 13
Views: 537

### Re: n, l ,ml, ms

It doesn't really matter which one you pick necessarily, as long as they are opposite spins. So you can't have two +1/2 together, but rather one +1/2 and one -1/2.
Fri Nov 01, 2019 12:47 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 8
Views: 71

### Re: Electron Affinity

Electron affinity generally decreases down a group of elements because each atom is larger than the atom above it. With a larger distance between the negatively-charged electron and the positively-charged nucleus, the force of attraction is relatively weaker, which causes the electron affinity to de...
Fri Nov 01, 2019 12:40 pm
Forum: Lewis Structures
Topic: Central atom
Replies: 6
Views: 44

### Re: Central atom

Professor Lavelle said that the central atom will have the lowest ionization energy.
Fri Nov 01, 2019 12:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Chemistry Community Posts
Replies: 2
Views: 44

### Re: Chemistry Community Posts

They're counted weekly (by Sunday 11:59PM), so you have to submit 5 per week in order to reach that 50 by the end of the quarter.
Fri Nov 01, 2019 12:19 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Writing electron configuration
Replies: 7
Views: 121

### Re: Writing electron configuration

PranaviKolla3G wrote:For an element like calcium, would the electron configuration end in 4s^2? And what about for Ca^2+?

Calcium would end on 4s2. For Ca^2+, because you are removing electrons, it'll become 3p6.
Fri Nov 01, 2019 12:14 pm
Forum: Electronegativity
Topic: Electronegativity on Test
Replies: 7
Views: 91

### Re: Electronegativity on Test

Because we haven't gone over it, I doubt that we'll need to be able to calculate the exact number. However, you should know the trends from the periodic table.
Wed Oct 23, 2019 12:49 pm
Forum: Ionic & Covalent Bonds
Topic: Week 4 Homework
Replies: 9
Views: 154

### Re: Week 4 Homework

I think you can still do Quantum World but you could also just squeeze in some problems about bonds, since that's what we're going over in lecture.
Wed Oct 23, 2019 12:44 pm
Forum: General Science Questions
Topic: Study Tips
Replies: 13
Views: 254

### Re: Study Tips

Do all of the homework problems and making sure you understand all of the topics in each of the learning outcomes of each outline! :)
I also think having a study group is helpful, as you can push each other to focus more.
Wed Oct 23, 2019 12:31 pm
Forum: Ionic & Covalent Bonds
Topic: Difference Between Ionic and Covalent
Replies: 8
Views: 468

### Re: Difference Between Ionic and Covalent

Ionic bonds are done between nonmetals and metals, while covalent bonds are formed between two nonmetals. Covalent is sharing, while ionic is donating.
Wed Oct 23, 2019 12:29 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 4
Views: 55

### Re: Electron Configurations

When looking at the periodic table, you kinda just go left to right and then down to the next row. The first two elements of each row on the left will be s, and the last 6 of the row are going to be p (except for the first row which is just 1s2 in total). You just go 1s2,2s2,2p6,3s2,3p6,... and so f...
Wed Oct 23, 2019 12:20 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity Trends
Replies: 5
Views: 67

### Re: Electron Affinity Trends

Electron affinity decreases down a group of elements because each atom is larger than the atom above it, and also increases left to right across a period. With a larger distance between the negatively-charged electron and the positively-charged nucleus, the force of attraction is relatively weaker, ...
Fri Oct 18, 2019 5:04 pm
Forum: Properties of Electrons
Topic: Momentum
Replies: 11
Views: 95

### Re: Momentum

Momentum depends upon the variables mass and velocity (p=mv), while velocity is displacement and time.
Fri Oct 18, 2019 4:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: How to Name Electron Configurations
Replies: 5
Views: 70

### Re: How to Name Electron Configurations

Whenever you have to write the electron configuration using previous elements, the question will say "noble gas configuration". You only use the noble gases when "using previous elements" in the configuration. So for example, the electron configuration for the element Chlorine is...
Fri Oct 18, 2019 4:47 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Noble Gas Shortcut
Replies: 3
Views: 49

### Re: Noble Gas Shortcut

You use the noble gas that is the one closest one before the element, so typically it'll be a row above the element you're working on. You should be able to just write [Ar] for argon.
Fri Oct 18, 2019 4:21 pm
Forum: Trends in The Periodic Table
Replies: 9
Views: 140

Within a period or family of elements, all electrons are added to the same shell. At the same time, protons are being added to the nucleus, making it more positively charged, which further indicates greater nuclear attraction. This means that the nucleus attracts the electrons more strongly, pulling...
Fri Oct 18, 2019 3:36 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions
Replies: 4
Views: 70

### Re: Exceptions

From what Lavelle said during lecture today, it's the only ones that we really need to know since we're only really looking at the first row of the d-block.
Fri Oct 11, 2019 12:30 pm
Forum: Student Social/Study Group
Topic: Weekly Posts
Replies: 6
Views: 122

### Re: Weekly Posts

^you can also check how many that you've posted by clicking "Quick Links" in the top left area, and clicking "Your posts" :)
Fri Oct 11, 2019 12:28 pm
Forum: DeBroglie Equation
Topic: Measurable V. Non-Measurable
Replies: 5
Views: 81

### Re: Measurable V. Non-Measurable

A particle with a De Broglie wavelength less than 10^-15m does not have detectable wave-like properties.
Fri Oct 11, 2019 12:26 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Accuracy and Precision
Replies: 8
Views: 237

### Re: Accuracy and Precision

It's just a fundamental topic to know for chemistry. We may not be focusing on it right now, but we'll need it when it comes to labs and such (similar to what the previous person wrote)
Fri Oct 11, 2019 12:20 pm
Forum: General Science Questions
Topic: Balancing Chemical Equations
Replies: 5
Views: 115

### Re: Balancing Chemical Equations

Be sure to pay attention to what type of reaction it is, so you don't miss anything important for the equation. You can't just add oxygen atoms to the reaction unless it's given (which it is for H17 :))
Fri Oct 11, 2019 12:12 pm
Forum: Properties of Electrons
Topic: Energy Level Relationship
Replies: 4
Views: 72

### Re: Energy Level Relationship

Professor Lavelle said that as the energy levels increase, the energy decreases :)
Thu Oct 03, 2019 10:29 pm
Forum: SI Units, Unit Conversions
Topic: which unit to use
Replies: 9
Views: 206

### Re: which unit to use

I was always taught to use the units given from the problem.
Thu Oct 03, 2019 10:27 pm
Forum: Balancing Chemical Reactions
Topic: Diatomic elements?
Replies: 8
Views: 127

### Re: Diatomic elements?

They come in pairs to be more stable ^^
Thu Oct 03, 2019 10:26 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 12
Views: 247

### Re: Combustion

Normally it does, however there are some cases where there is incomplete combustion and it actually produces carbon monoxide. But yeah, basically CO2 and H2O as products :)
Thu Oct 03, 2019 10:13 pm
Forum: SI Units, Unit Conversions
Topic: When to use what units
Replies: 5
Views: 128

### Re: When to use what units

It's normally easier and more efficient to convert the numbers to moles and liters, but if you just make sure the end result is in the right units, it should be fine.
Thu Oct 03, 2019 10:10 pm
Forum: SI Units, Unit Conversions
Topic: 2.Mass Percentage and Decimal Rounding:
Replies: 10
Views: 145

### Re: 2.Mass Percentage and Decimal Rounding:

I typically just match the sig figs to the periodic table values or the numbers given from the question itself. Make sure to never round til the end!!