Search found 89 matches

by Catherine Daye 1L
Sun Feb 23, 2020 11:48 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: porous disc
Replies: 5
Views: 10

Re: porous disc

A porous disc doesn’t the same thing as a salt bridge. They both ensure electron flow throughout the system.
by Catherine Daye 1L
Sun Feb 23, 2020 11:43 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 5
Views: 12

Re: salt bridge

The salt bridge allows for the flow of electrons.
by Catherine Daye 1L
Sun Feb 23, 2020 11:35 am
Forum: Balancing Redox Reactions
Topic: Oxidizing/reducing agent
Replies: 7
Views: 31

Re: Oxidizing/reducing agent

An oxidizing agent is what is being reduced and a reducing agent is what is being oxidized.
by Catherine Daye 1L
Sun Feb 23, 2020 10:54 am
Forum: Balancing Redox Reactions
Topic: Oxidizing/Reducing Agents
Replies: 11
Views: 25

Re: Oxidizing/Reducing Agents

Oxidizing agents are what’s being reduced and reducing agents are what’s being oxidized.
by Catherine Daye 1L
Sat Feb 22, 2020 11:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: relevance of salt bridge
Replies: 9
Views: 19

Re: relevance of salt bridge

Salt bridges allow for electron flow between beakers.
by Catherine Daye 1L
Wed Feb 19, 2020 1:39 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Intensive vs. Extensive
Replies: 15
Views: 38

Re: Intensive vs. Extensive

Intensive properties don't depend on the amount of a substance, while extensive properties do. For example, density is intensive but mass is extensive.
by Catherine Daye 1L
Wed Feb 19, 2020 1:38 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Spontaneous
Replies: 10
Views: 27

Re: Spontaneous

Spontaneous reactions are described as having a negative Gibbs free energy.
by Catherine Daye 1L
Wed Feb 19, 2020 1:36 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Adiabatic systems
Replies: 3
Views: 9

Re: Adiabatic systems

Yes, the definition is adiabatic is when heat doesn't transfer.
by Catherine Daye 1L
Wed Feb 19, 2020 1:34 am
Forum: Ideal Gases
Topic: pv=nrt
Replies: 19
Views: 67

Re: pv=nrt

Yes, this equation can be used at any time as long as these states remain constant.
by Catherine Daye 1L
Wed Feb 19, 2020 1:34 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: midterm question// Concentration ratio [ENDORSED]
Replies: 8
Views: 108

Re: midterm question// Concentration ratio [ENDORSED]

You have to think about how Ka=[A][H+]/[CB] (CB being conjugate base). By rearranging the equation, you can get Ka/[H+] = [A]/[CB], which is a ratio.
by Catherine Daye 1L
Sun Feb 09, 2020 10:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Ideal Gasses
Replies: 2
Views: 12

Re: Ideal Gasses

Yes, we should assume this unless the question states otherwise.
by Catherine Daye 1L
Sun Feb 09, 2020 10:23 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Material
Replies: 10
Views: 46

Re: Midterm Material

Yes, it will but just the basics since he only went over it a little bit.
by Catherine Daye 1L
Sun Feb 09, 2020 10:21 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX
Replies: 27
Views: 81

Re: ICE BOX

When it’s smaller than 10^-3
by Catherine Daye 1L
Sun Feb 09, 2020 10:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong Acids
Replies: 6
Views: 22

Re: Strong Acids

You need to memorize the strong acids (there are only a few) and strong bases are elements in the first 2 columns and OH
by Catherine Daye 1L
Sun Feb 09, 2020 10:19 pm
Forum: Student Social/Study Group
Topic: Midterm Studying
Replies: 5
Views: 40

Re: Midterm Studying

One thing you could do is look at the individual topic files he posts on his website. There’s a list of things you should know for each section and I use it like a checklist :)
by Catherine Daye 1L
Sat Feb 01, 2020 3:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Math Resources
Replies: 8
Views: 25

Re: Math Resources

Yes, they are on his website under math assistance!
by Catherine Daye 1L
Sat Feb 01, 2020 3:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Strong/weak acids & bases
Replies: 8
Views: 40

Re: Strong/weak acids & bases

Yes, the best way is to memorize the strong acids and bases (there aren’t too many). In general, a strong acids start with H and strong bases end with OH. Everything else you can assume is weak
by Catherine Daye 1L
Sat Feb 01, 2020 3:03 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 17
Views: 43

Re: Phase Changes

Yes, because the energy from the temperature is used to break/create bonds between molecules for their phase change.
by Catherine Daye 1L
Sat Feb 01, 2020 2:59 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Material
Replies: 13
Views: 72

Re: Midterm Material

It’s everything up to and including thermodynamics. There are review sessions posted on his website.
by Catherine Daye 1L
Sat Feb 01, 2020 2:56 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter + Heat Transfer
Replies: 4
Views: 11

Re: Calorimeter + Heat Transfer

When heat is lost (exothermic) there is a negative sign since q indicates heat gained. So when -q=q one thing loses heat and the other thing gains (+q) that heat lost.
by Catherine Daye 1L
Fri Jan 24, 2020 5:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Polyprotic Acids
Replies: 6
Views: 43

Re: Polyprotic Acids

K1 is when an acid/base dissociates for the first time. K2 is when the resulting conjugate base/acid from the previous reaction dissociates a second time.
by Catherine Daye 1L
Fri Jan 24, 2020 5:41 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Transition Temp.
Replies: 6
Views: 37

Re: Phase Transition Temp.

Temperature remains constant during a phase change because the energy that would increase temperature is instead being used to break bonds for a phase change.
by Catherine Daye 1L
Fri Jan 24, 2020 5:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q<K
Replies: 11
Views: 45

Re: Q<K

This is because the numerator of Q needs to increase to reach equilibrium (K value), and the concentration of products is the numerator.
by Catherine Daye 1L
Fri Jan 24, 2020 5:37 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pka
Replies: 4
Views: 18

Re: pka

A higher pKa means a weaker acid since pKa is -log [acid]
by Catherine Daye 1L
Fri Jan 24, 2020 5:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Steam
Replies: 5
Views: 17

Re: Steam

Steam causes more severe burns because it has more heat energy since there is a phase change from liquid to gas.
by Catherine Daye 1L
Sun Jan 19, 2020 4:56 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pH vs. pOH
Replies: 13
Views: 32

Re: pH vs. pOH

To calculate pOH, you use the concentration of a base. Alternatively, you calculate the pH using the concentration of an acid. The question may also include a Ka or Kb value. The Ka indicates the equilibrium constant of an acid (uses concentration of hydronium ions), and the Kb indicates the equilib...
by Catherine Daye 1L
Sun Jan 19, 2020 4:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to omit "x-term"
Replies: 6
Views: 27

Re: When to omit "x-term"

You can omit the x term when the K value is less than 10^-3.
by Catherine Daye 1L
Sun Jan 19, 2020 4:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Strong Acids/Bases vs. Weak Acids/Bases
Replies: 9
Views: 27

Re: Strong Acids/Bases vs. Weak Acids/Bases

You have to memorize the strong acids and bases. If the compound is not one of the memorized acids/bases, we assume they’re weak. In general, strong acids start with H and strong bases end with OH. Aside from that, there are a few obscure ones you should memorize.
by Catherine Daye 1L
Sun Jan 19, 2020 4:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH values of weak and strong acids
Replies: 6
Views: 32

Re: pH values of weak and strong acids

Acids make solutions that have a pH from 1-7, stronger acids making lower pH values than weak acids. pH doesn’t depend on concentration, but the strength of the acid/base.
by Catherine Daye 1L
Sun Jan 19, 2020 4:40 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE table
Replies: 11
Views: 36

Re: ICE table

Yes, we have to memorize strong acids and bases. The common rule is that strong acids start with H and strong bases end with OH. Then there are a few other obscure strong acids and bases you should memorize.
by Catherine Daye 1L
Fri Jan 10, 2020 10:26 am
Forum: Ideal Gases
Topic: Difference between K and Q
Replies: 9
Views: 31

Re: Difference between K and Q

K is used for when the reaction is at equilibrium, while Q is used for when the reaction is not. A reaction at equilibrium moves at a different rate than when it’s not at equilibrium. Therefore, they’re different numbers that you can compare to determine which direction the reaction favors.
by Catherine Daye 1L
Fri Jan 10, 2020 10:24 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for K
Replies: 10
Views: 45

Re: Units for K

The equilibrium constant K is the ratio of reactants to products, and ratios don’t have units.
by Catherine Daye 1L
Fri Jan 10, 2020 10:21 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Do solids and liquids count in Q?
Replies: 5
Views: 26

Re: Do solids and liquids count in Q?

Q is calculated the same way as K, so you only include gases and aqueous solutions.
by Catherine Daye 1L
Fri Jan 10, 2020 10:19 am
Forum: Ideal Gases
Topic: Reaction Quotient (Q)
Replies: 8
Views: 33

Re: Reaction Quotient (Q)

The reaction quotient is the rate of the equation when it’s not at equilibrium. This is important because you use it to determine which “direction” the reaction favors (towards products or reactants) by comparing it to the equilibrium constant K.
by Catherine Daye 1L
Fri Jan 10, 2020 10:17 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 4
Views: 19

Re: Kc and Kp

You use Kp for gases because it indicates partial pressure, since gases don’t really have a “concentration”. Kc is for concentrations of solids, liquids, and aqueous solutions.
by Catherine Daye 1L
Sat Dec 07, 2019 2:15 am
Forum: Identifying Acidic & Basic Salts
Topic: deciding whether the solution of a salt is basic, acidic, or neutral
Replies: 5
Views: 49

Re: deciding whether the solution of a salt is basic, acidic, or neutral

You should start by writing out the chemical equation of the salt in water. If the product has H+/H3O+, then the solution is acidic. If the product has OH-. then the solution is basic.
by Catherine Daye 1L
Sat Dec 07, 2019 2:12 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH in increasing temp
Replies: 2
Views: 25

Re: pH in increasing temp

Yes, but Dr. Lavelle said this is a chem 14b (I think) topic so we don't need to know this.
by Catherine Daye 1L
Sat Dec 07, 2019 2:10 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Weak vs Strong acids and bases
Replies: 6
Views: 32

Re: Weak vs Strong acids and bases

pH shows the concentration of hydronium ions in the solution. Weak acids result in a low concentration of hydronium ions because the hydrogen doesn't dissociate easily, therefore resulting in a less acidic solution (pH closer to 7).
by Catherine Daye 1L
Sat Dec 07, 2019 2:08 am
Forum: Conjugate Acids & Bases
Topic: Oxoacids
Replies: 4
Views: 51

Re: Oxoacids

An oxoacid is an acid with oxygen in the compound. It is important to note that metallic oxides are strong acids.
by Catherine Daye 1L
Sat Dec 07, 2019 2:06 am
Forum: Calculating the pH of Salt Solutions
Topic: pH vs. pOH
Replies: 17
Views: 128

Re: pH vs. pOH

pH indicates the concentration of hydronium, while pOH indicates the concentration of hydroxide. You can think of them as the extent of acidity and basicity (respectively).
by Catherine Daye 1L
Sat Dec 07, 2019 1:42 am
Forum: Dipole Moments
Topic: London Dispersion Forces
Replies: 4
Views: 38

Re: London Dispersion Forces

Yes, because all molecules have electrons, and LDFs occur when electron clouds are more dense in one direction.
by Catherine Daye 1L
Sat Dec 07, 2019 12:51 am
Forum: Naming
Topic: Naming Anionic Ligands
Replies: 3
Views: 33

Re: Naming Anionic Ligands

You can use either on the test, although Lavelle focuses on the older version in lecture.
by Catherine Daye 1L
Thu Dec 05, 2019 2:11 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: using Ka and Pka
Replies: 4
Views: 29

Re: using Ka and Pka

Ka is the dissociation constant and it shows how easily acids dissociate ([H+][anion]/[H-A]). The higher the Ka, the stronger the acid. PKa = -log[Ka]. The higher the PKa, the weaker the acid.
by Catherine Daye 1L
Thu Dec 05, 2019 2:06 pm
Forum: Student Social/Study Group
Topic: coordination compounds
Replies: 2
Views: 42

Re: coordination compounds

Chelating compounds create a ring when they create bonds, and polydentate compounds have multiple ligands. Compounds can be both chelating and polydentate, like CO3^-2
by Catherine Daye 1L
Thu Nov 28, 2019 3:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear VSEPR model
Replies: 21
Views: 130

Re: Linear VSEPR model

A molecule has a linear shape if it is bonded to 2 atoms and has no lone pairs, or bonded to 2 atoms and has 3 lone pairs.
by Catherine Daye 1L
Thu Nov 28, 2019 3:45 pm
Forum: Bronsted Acids & Bases
Topic: Acid vs Base
Replies: 4
Views: 47

Re: Acid vs Base

A Bronsted acid is distinguished by starting with H, and a Bronsted base usually ends with OH.
by Catherine Daye 1L
Thu Nov 28, 2019 3:40 pm
Forum: Naming
Topic: Iron as the central metal
Replies: 2
Views: 26

Re: Iron as the central metal

Ferrate is the name for [FeO4]^-2. Ferrous is for the cation Fe^2+ or iron(II).
by Catherine Daye 1L
Thu Nov 28, 2019 3:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: molecular shape
Replies: 8
Views: 47

Re: molecular shape

You look at the regions of electron density. Count the number of bonds and lone electron pairs around the central atom. That shows you the VSEPR formula (AXE), and you can determine the molecular shape.
by Catherine Daye 1L
Thu Nov 28, 2019 3:29 pm
Forum: Naming
Topic: Oxidation
Replies: 14
Views: 109

Re: Oxidation

An oxidation number is the number of electrons lost or gained when making a chemical bond. If it is a negative number, the atom will gain electrons. If it is a positive number, the atom will lose electrons.
by Catherine Daye 1L
Sun Nov 24, 2019 7:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs linear
Replies: 56
Views: 307

Re: Bent vs linear

A bent molecule has one or two lone pairs, while a linear molecule has three lone pairs or none.
by Catherine Daye 1L
Sun Nov 24, 2019 7:09 pm
Forum: Naming
Topic: Order in Naming
Replies: 12
Views: 56

Re: Order in Naming

The general rule is to put the atomic symbol in alphabetical order.
by Catherine Daye 1L
Sun Nov 24, 2019 7:08 pm
Forum: Hybridization
Topic: Sigma and Pi bonds
Replies: 13
Views: 57

Re: Sigma and Pi bonds

When labeling, one of the bonds is a pi bond, and the other is a sigma bond. Similarly, in a triple bond, one is a sigma bond, and the other two are pi bonds.
by Catherine Daye 1L
Sun Nov 24, 2019 7:07 pm
Forum: Lewis Acids & Bases
Topic: HCl vs HF
Replies: 19
Views: 98

Re: HCl vs HF

Because fluorine has a higher electronegativity than chlorine, its bond with hydrogen is stronger. Therefore, HCl dissociates more easily, making it a stronger acid due to its complete ionization.
by Catherine Daye 1L
Sun Nov 24, 2019 7:03 pm
Forum: Hybridization
Topic: Lone pairs
Replies: 9
Views: 42

Re: Lone pairs

Electron pairs are still important in the shape of the molecule, as they interact with the electron clouds of the atoms bonded to the central atom. Hybrid orbitals depend on the molecular shape, therefore, electron pairs are included in hybridization.
by Catherine Daye 1L
Sat Nov 16, 2019 11:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 4
Views: 32

Re: Bond Angles

I think you can just write what the textbook requires, which is <109.5. But you should write exact numbers for 90, 180, 120 degree angles.
by Catherine Daye 1L
Sat Nov 16, 2019 11:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polar or non polar?
Replies: 7
Views: 41

Re: polar or non polar?

You can kind of think polarity as "unevenness" because electrons are unevenly distributed. Therefore, you can look at how symmetrical a lewis structure is to determine it's polarity. If it is completely symmetrical, then it is most likely nonpolar. If it is not, then it is polar with a sid...
by Catherine Daye 1L
Sat Nov 16, 2019 11:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: identifying pi & sigma bonds
Replies: 3
Views: 37

Re: identifying pi & sigma bonds

Sigma bonds are in single bonds, double bonds, and triple bonds; it's kind of like the first bond. Pi bonds are in double bonds and triple bonds; it's kind of like the subsequent bonds to pi bonds. Single bonds have one sigma bond, double bonds have one sigma bond and one pi bond, and triple bonds h...
by Catherine Daye 1L
Sat Nov 16, 2019 11:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Studying
Replies: 14
Views: 108

Re: Final Studying

I've been reviewing the midterm and looking at concepts I didn't fully understand. I'm also doing problems in the textbook since some of the questions may be on the final.
by Catherine Daye 1L
Sat Nov 16, 2019 4:49 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Electron configuration
Replies: 7
Views: 76

Re: Electron configuration

The 4s orbital is lower in energy. However, when it is full, it becomes higher in energy than 3d. This explains why we write electron configurations like 3d^2 4s^2 4p^6.
by Catherine Daye 1L
Sat Nov 09, 2019 4:58 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bond Strength
Replies: 8
Views: 55

Re: Hydrogen Bond Strength

Hydrogen bonds are weaker than ionic and covalent bonds, but hydrogen bonds are the strongest of the intermolecular forces.
by Catherine Daye 1L
Sat Nov 09, 2019 4:56 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Dipole-dipole v. Induced Dipole-Induced Dipole
Replies: 2
Views: 20

Re: Dipole-dipole v. Induced Dipole-Induced Dipole

A dipole-dipole force is between molecules that are always polar. An induced dipole-induced dipole force is between molecules that have instantaneous dipole moments; the electrons move around, making the molecule temporarily polar.
by Catherine Daye 1L
Sat Nov 09, 2019 4:49 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Hydrogen Bonding
Replies: 4
Views: 29

Re: Hydrogen Bonding

I think this is because they are very electronegative. Especially because they have small radii, it has strong bonds with hydrogen, which has the smallest radius of all the elements.
by Catherine Daye 1L
Sat Nov 09, 2019 4:45 pm
Forum: Bond Lengths & Energies
Topic: Bonds
Replies: 6
Views: 45

Re: Bonds

Sigma bonds are in all bonds, and pi bonds are in double and triple bonds. Single bonds have one sigma bond, double bonds have a sigma and a pi bond, and triple bonds have a sigma and two pi bonds.
by Catherine Daye 1L
Sat Nov 09, 2019 4:42 pm
Forum: Bond Lengths & Energies
Topic: Resonance structure bond lengths?
Replies: 3
Views: 38

Re: Resonance structure bond lengths?

Bond length is the distance between the two nuclei of the elements. The electron clouds influence bond lengths by making the elements farther/closer from each other with electron-electron repulsion.
by Catherine Daye 1L
Sat Nov 02, 2019 4:50 pm
Forum: Lewis Structures
Topic: Determining most stable Lewis structure
Replies: 5
Views: 44

Re: Determining most stable Lewis structure

Although they are both important, formal charge is slightly more important. Not all lewis structures will be symmetrical.
by Catherine Daye 1L
Sat Nov 02, 2019 4:49 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity difference >1.5 but <2
Replies: 3
Views: 22

Re: Electronegativity difference >1.5 but <2

This doesn't really answer the question, but it's interesting to note that this also demonstrates how some ionic bonds demonstrate a more covalent character than others. If one bond has a really high electronegativity difference, it demonstrates less covalent character than one that has an electrone...
by Catherine Daye 1L
Sat Nov 02, 2019 12:39 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Understanding Ionic Radius
Replies: 3
Views: 21

Re: Understanding Ionic Radius

Yes, because even though isoelectronic ions have the same number of electrons, they still have differing numbers of protons. When there are more protons in the nucleus, there is a stronger pull. Therefore, isoelectronic ions have the same electron-electron repulsion but different pulls from the nucl...
by Catherine Daye 1L
Sat Nov 02, 2019 12:32 pm
Forum: Trends in The Periodic Table
Topic: Noble Gases
Replies: 10
Views: 33

Re: Noble Gases

No, they don't because they have all 8 valence electrons. These trends are based on the fact that elements tend to want to have a full valence shell. For example, ionization energy is the amount of energy it takes to remove an electron. Group 1 has low ionization energy because they want to lose the...
by Catherine Daye 1L
Sat Nov 02, 2019 12:22 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: General Question about Orbital... Filling..?
Replies: 5
Views: 32

Re: General Question about Orbital... Filling..?

The d orbital is lower in energy than the s orbital, so when you write the electron configuration you always write the d orbital first. For example, ... 3d^10 4s^2 4p^6, ... 4d^10 5s^2 etc.
by Catherine Daye 1L
Thu Oct 24, 2019 8:26 pm
Forum: Trends in The Periodic Table
Topic: Aufbau Principle
Replies: 11
Views: 85

Re: Aufbau Principle

He might also ask questions that require you to differentiate the three different principles we learned. Ex. what principle explains the electron configuration 1s^2 2s^2 2p^6 for carbon? why can't 1s^2 2s^2 2p^3 (nitrogen) have paired electrons?
by Catherine Daye 1L
Thu Oct 24, 2019 1:50 pm
Forum: *Particle in a Box
Topic: TEST 2
Replies: 13
Views: 185

Re: TEST 2

I think the best way to study is to do practice problems. You learn how to solve a bunch of different problems on the same topic and won't be blindsided if a problem is worded weirdly.
by Catherine Daye 1L
Thu Oct 24, 2019 1:42 pm
Forum: Lewis Structures
Topic: Ion lewis structure
Replies: 9
Views: 59

Re: Ion lewis structure

Yes, there are a few exceptions to the octet rule. This includes molecules with an odd number of electrons (ex. nitrogen), molecules with atoms that have more than 8 electrons (ex. sulfur), and molecules with atoms that have less than 8 electrons (ex. boron).
by Catherine Daye 1L
Thu Oct 24, 2019 1:32 pm
Forum: Trends in The Periodic Table
Topic: Ionic Radii
Replies: 10
Views: 81

Re: Ionic Radii

Anions are larger because they add another electron, creating more electron-electron repulsion between the valence shell electrons and the electrons in the shell below it (increasing distance between the shells). Cations are smaller because they remove an electron, decreasing the amount of electron-...
by Catherine Daye 1L
Thu Oct 24, 2019 1:24 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic v.covalent bonds
Replies: 7
Views: 41

Re: Ionic v.covalent bonds

Yes, exactly! Also, note that elements in ionic compounds give and take electrons from each other, while elements in covalent compounds share electrons.
by Catherine Daye 1L
Sun Oct 20, 2019 3:14 pm
Forum: Balancing Chemical Reactions
Topic: Balancing equations.
Replies: 12
Views: 160

Re: Balancing equations.

A good trick is to write down a mini chart under the equation where you write down the elements and the number of moles for the reactant side and product side. Ie Reactants --> C 3, O 1, H4 Products --> C 1, O 2, H 2. This might help you keep track of your numbers without making your work too messy.
by Catherine Daye 1L
Sat Oct 19, 2019 3:53 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: HW 1B #27
Replies: 2
Views: 25

Re: HW 1B #27

The question is saying the bowling ball is moving at 5+5 m/s (10 m/s) or 5-5 m/s (0 m/s). That's why you multiply the mass by 10 m/s.
by Catherine Daye 1L
Sat Oct 19, 2019 3:32 pm
Forum: Trends in The Periodic Table
Topic: Problem 1.13
Replies: 2
Views: 37

Re: Problem 1.13

This is because oxygen has one electron pair in the outer shell, while nitrogen has none. The electron pair contains electron-electron repulsion, making it easier to remove the most loosely bound electron, meaning it has low ionization energy.
by Catherine Daye 1L
Thu Oct 17, 2019 7:14 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Theoretical vs. Actual Yield
Replies: 38
Views: 499

Re: Theoretical vs. Actual Yield

Actual yield is less than theoretical due to almost unavoidable mistakes, for example, slight inaccuracies in measuring out reactants or some of the product sticking to the side of the beaker when measuring. Theoretical yield is the largest possible yield in a reaction, as it assumes there are no mi...
by Catherine Daye 1L
Sat Oct 12, 2019 5:10 pm
Forum: Empirical & Molecular Formulas
Topic: Mass Percentage Question
Replies: 9
Views: 212

Re: Mass Percentage Question

First, write down the molar masses of each element in the compound. Then find the molar mass of the compound by adding the atomic masses of the elements (making sure to account for the additional atoms ex. O2 is 32 g/mol). Finally, find the mass percent for each element using the equation [(molar ma...
by Catherine Daye 1L
Sat Oct 12, 2019 5:01 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 16
Views: 167

Re: Atomic Radius

The radius is only measured when the element is in its ground state!
by Catherine Daye 1L
Sat Oct 12, 2019 4:58 pm
Forum: Properties of Light
Topic: c vs. v...
Replies: 3
Views: 41

Re: c vs. v...

I think that equation applies only to electromagnetic waves!
by Catherine Daye 1L
Sat Oct 12, 2019 4:32 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 4
Views: 584

Re: Electronegativity

I don't think so, but it should be helpful to know that electronegativity increases the closer it is to fluorine since it's the element with the highest electronegativity.
by Catherine Daye 1L
Sat Oct 12, 2019 4:18 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent
Replies: 29
Views: 600

Re: Ionic vs Covalent

Ionic bonds are stronger than covalent bonds because elements give/take electrons, whereas elements with covalent bonds share electrons.
by Catherine Daye 1L
Sat Oct 12, 2019 4:16 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation [ENDORSED]
Replies: 73
Views: 1737

Re: Rydberg equation [ENDORSED]

You use the Rydberg equation to calculate the wavelength of light released when an electron jumps down to lower energy levels.
by Catherine Daye 1L
Sun Oct 06, 2019 9:18 pm
Forum: General Science Questions
Topic: Order of Elements When Writing Out a Compound
Replies: 8
Views: 132

Re: Order of Elements When Writing Out a Compound

I think it's supposed to be in alphabetical order (ex. hydrogen, carbon, chlorine, oxygen). After taking chem for a while and getting used to seeing a bunch of different compounds, putting them in order will become automatic. :)
by Catherine Daye 1L
Sun Oct 06, 2019 7:38 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Reactions
Replies: 25
Views: 297

Re: Balancing Reactions

This is important because the Law of Conservation of Mass states that total mass before (reactants) must equal total mass after (products). In addition, when conducting experiments, you need to know how many moles of each chemical you need to create a reaction.
by Catherine Daye 1L
Sun Oct 06, 2019 7:35 pm
Forum: Limiting Reactant Calculations
Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Replies: 68
Views: 1678

Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]

I think getting to the correct answer is the most important thing, but work helps the grader understand your line of thought. By showing work, you can also learn from your mistakes, i.e. which step you got confused on.
by Catherine Daye 1L
Sun Oct 06, 2019 7:32 pm
Forum: Balancing Chemical Reactions
Topic: Advice for Test 1
Replies: 7
Views: 82

Re: Advice for Test 1

I think it might be helpful to look at his modules, on top of the homework. That way, you get a feel of the types of questions he likes to ask!
by Catherine Daye 1L
Sun Oct 06, 2019 7:29 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 169
Views: 103680

Re: Rusty on High School Chem [ENDORSED]

Hey! I'm not sure if this works for everyone but it definitely helps me. I took chem a while ago and I forgot a lot of information, but doing practice problems in the textbook and online helps a lot. I just look up something like "limiting reactant problems". Each question, easy or hard, h...

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