Search found 93 matches

by Christine Honda 2I
Wed Feb 19, 2020 9:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Material
Replies: 8
Views: 19

Re: Test 2 Material

As Dr. Lavelle mentioned at the end of the lecture today, the test will cover the second page of the Thermodynamics outline and all of the Electrochemistry Outline. But the test will NOT include Chemical Kinetics.
by Christine Honda 2I
Wed Feb 19, 2020 9:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode and Cathode position
Replies: 5
Views: 19

Re: Anode and Cathode position

It is conventional to put the anode on the left and the cathode on the right. That being said it would be smart to double-check that this is true in a problem or on a test (if possible) by seeing which is being reduced and which is being oxidized.
by Christine Honda 2I
Wed Feb 19, 2020 9:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Gibbs free energy
Replies: 5
Views: 11

Re: Gibbs free energy

G* means that all the substances are in their standard states
by Christine Honda 2I
Wed Feb 19, 2020 9:15 pm
Forum: Balancing Redox Reactions
Topic: Homework 6K.5 Part B
Replies: 1
Views: 6

Re: Homework 6K.5 Part B

Br is both the oxidizing and reducing agent.
We balance it assuming using the fact that it is an aqueous solution so H2O.

3Br2 + 6OH- --> 5Br- + BrO3- + 3H2O
by Christine Honda 2I
Wed Feb 19, 2020 9:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Dead Battery
Replies: 6
Views: 16

Re: Dead Battery

The absence of the flow of electrons or charge between the anode and cathode can also be solved by using a salt bridge!
by Christine Honda 2I
Tue Feb 18, 2020 1:31 am
Forum: Balancing Redox Reactions
Topic: Reduction vs. oxidation
Replies: 29
Views: 64

Re: Reduction vs. oxidation

One thing my high school teacher taught me to remember oxidation/reduction is L.E.O (loses electrons oxidation) the lion goes G.E.R (gaining electrons reduction)! Hope this helps make memorization easier :)
by Christine Honda 2I
Thu Feb 06, 2020 12:43 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Textbook question 4A.13
Replies: 5
Views: 24

Re: Textbook question 4A.13

Qreaction=-Qcalorimeter and so that is why the answer is negative 1.19kJ!
by Christine Honda 2I
Sun Feb 02, 2020 5:57 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Variables
Replies: 3
Views: 18

Re: Variables

As someone else said I think it would be a good thing to familiarize yourself with the Constants and Equations sheet that's on Dr. Lavelle's website and it is likely that you will be able to deduce what each variable is!
by Christine Honda 2I
Sun Feb 02, 2020 5:09 pm
Forum: Phase Changes & Related Calculations
Topic: Liquid/Steam
Replies: 3
Views: 20

Liquid/Steam

Can someone explain to me why steam causes worse burns than boiling water? I know he went over it in great detail during lecture but I want to be sure that I have the concepts solidified.
by Christine Honda 2I
Sun Feb 02, 2020 4:59 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter
Replies: 5
Views: 27

Re: Calorimeter

A bomb calorimeter is completely sealed and insulated, making it an isolated system. It maintains a constant volume.
A constant pressure calorimeter gives enthalpy values.
by Christine Honda 2I
Sun Feb 02, 2020 4:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy units
Replies: 5
Views: 15

Re: Enthalpy units

It should be in terms of Joules whether that is J or kJ. It can also be in J/mol or kJ/mol depending on the context.
by Christine Honda 2I
Sun Feb 02, 2020 4:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: thermochemistry equations
Replies: 5
Views: 20

Re: thermochemistry equations

Make sure to familiarize yourself with the Constants and Equations sheet on Dr. Lavelle's website, therefore, you know what you should and shouldn't memorize!
by Christine Honda 2I
Sun Jan 26, 2020 8:10 pm
Forum: Phase Changes & Related Calculations
Topic: Standard State
Replies: 1
Views: 18

Re: Standard State

Typically a substance is in its standard state when a gas is at 1 atm and 1M. For a pure liquid or sold it is most stable at 1 atm and a temperature of interest or about 25C.
by Christine Honda 2I
Sun Jan 26, 2020 8:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Method 2
Replies: 4
Views: 16

Re: Method 2

In Method 2 you use each individual bond enthalpies to calculate delta H. Using the Lewis structures you look at which bonds are broken in the reactants and which bonds are formed in the products. The bonds broken are positive enthalpies and bonds formed are negative. Then you add the enthalpies of ...
by Christine Honda 2I
Sun Jan 26, 2020 8:05 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 7
Views: 30

Re: Phase Changes

If the substance is not in the most stable/standard phases then you must use the total of the enthalpy of the phase change and the bond enthalpy when calculating.
by Christine Honda 2I
Sun Jan 26, 2020 8:02 pm
Forum: Phase Changes & Related Calculations
Topic: Focus 4 Homework Questions
Replies: 3
Views: 23

Re: Focus 4 Homework Questions

I would definitely start with 4D because that's what addresses enthalpy!
by Christine Honda 2I
Sun Jan 26, 2020 8:00 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: percent ionization
Replies: 5
Views: 12

Re: percent ionization

The small percent ionization indicates the change in molar concentration or x is so small that it becomes negligible and this makes the approximation acceptable.
by Christine Honda 2I
Sun Jan 19, 2020 7:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Stoichiometric coefficients for pH/pOH
Replies: 3
Views: 16

Re: Stoichiometric coefficients for pH/pOH

No, you do not need to raise it to the stoichiometric coefficients because when you take the pOH you are taking the -log of the concentration of OH- ions, not the ratio of them.
by Christine Honda 2I
Sun Jan 19, 2020 7:43 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Shift Of Reaction
Replies: 4
Views: 16

Re: Shift Of Reaction

It means that the reaction has to shift towards the reactants or products in order to achieve the same ratio and the same K value.
by Christine Honda 2I
Sun Jan 19, 2020 7:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5%
Replies: 4
Views: 14

Re: 5%

The 5% rule applies to when you use the ICE table. If K is less than 10^-3, then you can assume that X is so small that it will not make a difference. For example if you have K=X^2/(0.3-X), then you can change it to X^2/0.3 because the X in the denominator becomes negligible. The 5% rule is if you f...
by Christine Honda 2I
Sun Jan 19, 2020 7:00 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Molar concentration of acids & bases
Replies: 8
Views: 18

Re: Molar concentration of acids & bases

If it asks for molar concentrations I believe it is asking for mol/L. pH or pOH will be asked for specifically.
by Christine Honda 2I
Sun Jan 19, 2020 6:55 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Strong Acids/Bases vs. Weak Acids/Bases
Replies: 9
Views: 26

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

In discussion, my TA mentioned these as strong acids and bases! I think they would be helpful to memorize so that you know which acids or bases completely dissociate.
Strong Acids: HCl, HNO3, H2SO4, HBr, HI, HClO4
Strong Bases: LiOH, NaOH, KOH, Ca(OH)2, Ba(OH)2, Sr(OH)2
by Christine Honda 2I
Sun Jan 19, 2020 6:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% rule
Replies: 3
Views: 20

Re: 5% rule

The 5% percent rule is used to check if our "X is small" approximation is valid or not. We check to see if the X we solve for is less than 5% of the initial concentration. If it IS less than 5% then the approximation is valid.
by Christine Honda 2I
Sun Jan 19, 2020 6:48 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE Tables
Replies: 13
Views: 35

Re: ICE Tables

H2O is often not included because it is a liquid, or solvent in the solution. Therefore, it is not included in the K expression or in the ICE table.
by Christine Honda 2I
Sun Jan 19, 2020 6:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework problem 5.I.15
Replies: 4
Views: 16

Re: Homework problem 5.I.15

I don't think ICE tables are necessary to get full credit on tests as long as you get the right answer. Although I would suggest using one because there's possible partial credit.
by Christine Honda 2I
Sun Jan 19, 2020 6:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.I.23
Replies: 3
Views: 19

Re: 5.I.23

You still need to include the H2O in the equilibrium expression. You can only disregard it if it is a solid or liquid!
by Christine Honda 2I
Sun Jan 19, 2020 6:40 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5I.19
Replies: 1
Views: 18

Re: 5I.19

Since we know that 60% of the H2 reacted, then at equilibrium we can use the fact that there will be 40% left when solving for the equilibrium concentrations. Therefore, when we use the ICE table, we can set the change in H2 (0.133-x) equal to the equilibrium value of H2 (0.4 x 0.133) and solve for X!
by Christine Honda 2I
Sun Jan 19, 2020 6:37 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 5I.29
Replies: 1
Views: 7

Re: 5I.29

Using the reaction given, set up an ICE table. You should get a Kp equation that looks like x^2/(0.22-2x)^2 and set this equal to the Kp given. Because the equilibrium constant is small, we can assume that X is negligible compared to 0.22, therefore we can ignore it in the denominator. We end up hav...
by Christine Honda 2I
Wed Jan 15, 2020 10:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K units
Replies: 10
Views: 35

Re: K units

For the purpose of this class, K is unitless. But in higher classes, it refers to the "activity" of the reactants and products.
by Christine Honda 2I
Sat Dec 07, 2019 5:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in Position
Replies: 1
Views: 29

Re: Uncertainty in Position

Yes! The diameter is the uncertainty in position.
by Christine Honda 2I
Sat Dec 07, 2019 5:18 pm
Forum: Biological Examples
Topic: Polydentate
Replies: 3
Views: 26

Re: Polydentate

Polydentate is referring to anything that can bind in two or more places. I would describe EDTA as a hexadentate to be more specific!
by Christine Honda 2I
Fri Dec 06, 2019 4:23 pm
Forum: Bronsted Acids & Bases
Topic: J.13 B
Replies: 1
Views: 24

Re: J.13 B

Yes, CH3COOH is the acid and CH3NH2 is the base!
by Christine Honda 2I
Fri Dec 06, 2019 4:19 pm
Forum: Sigma & Pi Bonds
Topic: hybridization and sigma and pi bonds
Replies: 1
Views: 33

Re: hybridization and sigma and pi bonds

The triple bond between C and N has one sigma bond and two pi bonds.
The sigma bond is written as sigma(Chybridization,Nhybridization)
Then you will have two pi bonds are written as pi(C2p,N2p)
by Christine Honda 2I
Fri Dec 06, 2019 4:13 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating KA
Replies: 1
Views: 18

Re: Calculating KA

For 14A we will not have to calculate the Ka for weak acids. We will learn that in 14B. I would know how to calculate the pKa of a weak acid when given Ka though assuming that it is given to us.
by Christine Honda 2I
Sun Dec 01, 2019 7:32 pm
Forum: Dipole Moments
Topic: dipole moments
Replies: 6
Views: 43

Re: dipole moments

Yes, polar molecules possess a permanent dipole moment.
by Christine Honda 2I
Sun Dec 01, 2019 7:30 pm
Forum: Naming
Topic: Naming Order
Replies: 5
Views: 33

Re: Naming Order

(Greek Prefix) Ligand names in alphabetical order, Transition Metal Cation Name (Roman Numeral). If there are anions, then add it to the end. If there is water then add (Greek Prefix) Hydrate.
by Christine Honda 2I
Sun Dec 01, 2019 7:27 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Diamagnetism and Paramagnetism
Replies: 2
Views: 25

Re: Diamagnetism and Paramagnetism

A paramagnetic electron is an unpaired electron. An atom is considered paramagnetic if even one orbital has a net spin. Diamagnetic electrons are whenever two electrons are paired together in an orbital, or their total spin is 0. Also, diamagnetic atoms/compounds (and atoms) have paired electrons an...
by Christine Honda 2I
Sun Dec 01, 2019 7:25 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Random Example
Replies: 1
Views: 23

Re: Random Example

Since this is a coordination compound the lewis structure would have the transition metal in the middle and the ligands in bonded to it, all in square brackets.
by Christine Honda 2I
Sun Dec 01, 2019 7:24 pm
Forum: *Crystal Field Theory
Topic: Crystal Field Theory
Replies: 3
Views: 50

Re: Crystal Field Theory

Crystal field theory (CFT) is a bonding model that explains many important properties of transition-metal complexes, including their colors, magnetism, structures, stability, and reactivity. It qualitatively describes the strength of the metal-ligand bonds in transition-metal complexes. Based on the...
by Christine Honda 2I
Sun Dec 01, 2019 7:17 pm
Forum: Naming
Topic: 9C.1
Replies: 1
Views: 32

Re: 9C.1

To figure out the charge of the metal you can look at the ligands and overall charge of the complex. Since there are 6 CN- and the overall charge is 4-, that means the charge of Fe is 2+. To name the compound, you should write out the name for it by beginning with each ligand, in alphabetical order,...
by Christine Honda 2I
Sun Nov 24, 2019 6:12 pm
Forum: Hybridization
Topic: Strength of sigma vs pi bonds
Replies: 6
Views: 29

Re: Strength of sigma vs pi bonds

A sigma bond is stronger. Sigma bonds result from the head-on overlap of the orbitals of the two atoms, which has more area of overlap than pi bonds which result from the parallel overlap of orbitals. That is why sigma bonds are stronger.
by Christine Honda 2I
Sun Nov 24, 2019 6:11 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: diamagnetism
Replies: 5
Views: 42

Re: diamagnetism

Any time two electrons share the same orbital, their spin quantum numbers have to be different. Whenever two electrons are paired together in an orbital, or their total spin is 0, they are diamagnetic electrons.
by Christine Honda 2I
Sun Nov 24, 2019 6:10 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: paramagnetism
Replies: 6
Views: 52

Re: paramagnetism

A paramagnetic electron is an unpaired electron. An atom is considered paramagnetic if even one orbital has a net spin.
by Christine Honda 2I
Sun Nov 24, 2019 6:06 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Reactivity of pi bonds
Replies: 2
Views: 32

Re: Reactivity of pi bonds

Sigma bonds result from the head-on overlap of the orbitals of the two atoms, which has more area of overlap than pi bonds which result from the parallel overlap of orbitals. That is why sigma bonds are stronger.
by Christine Honda 2I
Sun Nov 24, 2019 1:54 pm
Forum: Biological Examples
Topic: Heme complex
Replies: 8
Views: 52

Re: Heme complex

A heme complex forms when an iron ion binds to the porphyrin ligand. The porphyrin ligand is a tetradentate ring structure, meaning the fact that there are four nitrogens facing inward that can can form coordination complexes with the iron. When this complex binds with another protein they make up m...
by Christine Honda 2I
Sun Nov 24, 2019 1:48 pm
Forum: Hybridization
Topic: sp3 hybridization
Replies: 1
Views: 26

Re: sp3 hybridization

The characteristic tetravalence of carbon is due to the small promotion energy of a carbon atom. This energy is small because a 2s-electron is transferred from an orbital that it shares with another electron to an empty 2p-orbital. Although the promoted electron enters an orbital of higher energy, i...
by Christine Honda 2I
Sun Nov 17, 2019 8:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Radicals
Replies: 5
Views: 35

Re: Radicals

The VESPR theory applies to radicals, and they can be counted as electron densities. For example, in CH3 you have 7 total electrons it's going to be a trigonal planar you're going to have the Carbon as the central atom that is bonded to 3 H's and then you have one electron (unpaired lone pair) on th...
by Christine Honda 2I
Sun Nov 17, 2019 8:00 pm
Forum: Hybridization
Topic: VSEPR Models
Replies: 1
Views: 16

Re: VSEPR Models

The VSEPR model is used to determine the molecular geometry and the electron-group geometry. The Lewis structure helps us identify the bond pairs and the lone pairs.
by Christine Honda 2I
Sun Nov 17, 2019 2:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.1
Replies: 1
Views: 24

Re: 2E.1

The one with the bond angle as 120 degrees must have lone pairs. The one that is 180 degrees may have lone pairs.
by Christine Honda 2I
Sun Nov 17, 2019 1:14 pm
Forum: Bond Lengths & Energies
Topic: Polarizability
Replies: 4
Views: 34

Re: Polarizability

Typically, cations will have less polarizability because there are less electrons and therefore the effective nuclear charge on the electrons are stronger and pulled in closer to the nucleus. Therefore, it is harder to "distort" the electron cloud making it less polarizable. The opposite i...
by Christine Honda 2I
Sun Nov 17, 2019 1:13 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Hydrogen Bonds
Replies: 3
Views: 18

Re: Hydrogen Bonds

Yes, hydrogen bonds are the strongest IMF. The δ+ hydrogen is so strongly attracted to the lone pair on the other atom that it is almost as if you were beginning to form a covalent bond. It doesn't go that far, but the attraction is significantly stronger than an ordinary dipole-dipole interaction.
by Christine Honda 2I
Sun Nov 17, 2019 1:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair location
Replies: 3
Views: 35

Re: Lone Pair location

In the see-saw shape the axial and equatorial positions are not chemically equivalent. If the lone pair is in the axial position, we have three LP–BP repulsions at 90°. If the lone pair is in the equatorial position, we have two 90° LP–BP repulsions at 90°. With fewer 90° LP–BP repulsions, we can pr...
by Christine Honda 2I
Sun Nov 10, 2019 9:55 pm
Forum: Electronegativity
Topic: Electron affinity
Replies: 6
Views: 28

Re: Electron affinity

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. Electron affinity is defined as the change in energy (in kJ/mole) of a neutral atom (in the gaseous phase) when an electron is added to the atom to form a negative ion.
by Christine Honda 2I
Sun Nov 10, 2019 1:52 pm
Forum: Electronegativity
Topic: Ionization energy of O vs N
Replies: 6
Views: 33

Re: Ionization energy of O vs N

Since there are two electrons in the first orbital of the O sublevel, there is greater electronic repulsion in the 2p sublevel for O than N. Therefore, it is easier to remove an electron from the O than the N, and the ionization energy of O is lower than N. Also nitrogen has a lower ionization energ...
by Christine Honda 2I
Sun Nov 10, 2019 1:50 pm
Forum: Dipole Moments
Topic: Dipole moments
Replies: 3
Views: 21

Re: Dipole moments

Yes, dipole moments is referring to the fact that one atom is more electronegative. The larger the difference in electronegativity, the larger the dipole moment. It is conventional to draw a dipole moment arrow from positive to negative.
by Christine Honda 2I
Sun Nov 10, 2019 1:39 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Equation?
Replies: 12
Views: 48

Re: Formal Charge Equation?

305416361 wrote:
Victoria Otuya 4F wrote:I learned an easier way to remember the formal charge equation: valence electron -(dots + line).


does this count "dots" as pairs of dots or individual ones?


Count each dot as one electron each.
by Christine Honda 2I
Sun Nov 10, 2019 1:25 pm
Forum: Dipole Moments
Topic: Boiling Point
Replies: 11
Views: 64

Re: Boiling Point

Professor Lavelle uses boiling points to indicate which dipole interactions are stronger because the stronger the interactions between molecules, the more energy/heat required to separate them from each other, which raises the boiling point of the molecule.
by Christine Honda 2I
Sun Nov 10, 2019 1:17 pm
Forum: Bond Lengths & Energies
Topic: polarizability
Replies: 9
Views: 33

Re: polarizability

When polarizability of molecules increases, it takes more energy to break the stronger bonds between molecules resulting higher melting and boiling points.
by Christine Honda 2I
Sun Nov 03, 2019 11:19 pm
Forum: Quantum Numbers and The H-Atom
Topic: magnetic quantum number
Replies: 5
Views: 23

Re: magnetic quantum number

The magnetic quantum number tells you how many orbitals there are in a subshell and it tells you the orientation of the orbital.
by Christine Honda 2I
Sun Nov 03, 2019 11:17 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: +- vs Uncertainty
Replies: 3
Views: 56

Re: +- vs Uncertainty

Use 0.5 for the uncertainty!
by Christine Honda 2I
Sun Nov 03, 2019 12:41 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Which equations can be used for what topics
Replies: 2
Views: 32

Re: Which equations can be used for what topics

You can use c=(lambda)(nu) for electromagnetic radiation, or light.
You can use lambda=h/p or lambda=h/mv for electrons because they have mass.
by Christine Honda 2I
Sun Nov 03, 2019 12:35 am
Forum: Electronegativity
Topic: Ionization energy and electronegativity
Replies: 8
Views: 30

Re: Ionization energy and electronegativity

Electronegativity is a measurement of a neutral atom's likelihood of gaining an electron.
Ionization energy is the minimum energy required to remove a valence electron.
Both of these have the trend of increasing going towards the right and increasing going up the periodic table.
by Christine Honda 2I
Sun Nov 03, 2019 12:32 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations of ions
Replies: 4
Views: 39

Re: Electron configurations of ions

I think it is important to write the ground state first so that we can see which orbital has the highest energy so we can easily see where to remove or add electrons. It may not be totally necessary though, more just useful.
by Christine Honda 2I
Sun Nov 03, 2019 12:30 am
Forum: Properties of Light
Topic: Equations
Replies: 4
Views: 28

Re: Equations

I'm assuming they will be given to us because Dr. Lavelle's Constants and Equations sheet on his site has all three of these equations on it!
by Christine Honda 2I
Sun Oct 27, 2019 10:17 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy Unit
Replies: 6
Views: 39

Re: Ionization Energy Unit

kJ/mol!
by Christine Honda 2I
Sun Oct 27, 2019 10:16 pm
Forum: Trends in The Periodic Table
Topic: Cations vs Parent atoms
Replies: 4
Views: 31

Re: Cations vs Parent atoms

Cations are smaller than their parent ions because cations lose electrons and when an atom loses electrons, the positively charged nucleus pulls the electrons more closely making it smaller.
by Christine Honda 2I
Sat Oct 26, 2019 11:39 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Pauli Exclusion Principle
Replies: 3
Views: 21

Re: Pauli Exclusion Principle

The spins of two electrons are said to be paired if one is ↑ and the other ↓. Paired spins are denoted ↑↓, and electrons with paired spins have spin magnetic quantum numbers of opposite signs. No two electrons in an atom can have the same set of four quantum numbers.
by Christine Honda 2I
Sat Oct 26, 2019 2:16 pm
Forum: Ionic & Covalent Bonds
Topic: Atomic Radius
Replies: 4
Views: 32

Re: Atomic Radius

Atomic size decreases from left to right across a period of elements. This is because protons are being added to the nucleus making it more positively charged as well as the fact that electrons are added to the same shell. This creates greater nuclear attraction and therefore the electrons are pulle...
by Christine Honda 2I
Sat Oct 26, 2019 2:10 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Special elements
Replies: 2
Views: 14

Re: Special elements

The two main exceptions are Chromium ([Ar]3d^5 4s^1) and Copper ([Ar] 3d^10 4s^1)

These are exceptions to the general rule because a completely full or half full d sub-level is more stable than a partially filled d sub-level.
by Christine Honda 2I
Sat Oct 26, 2019 1:43 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Energy Level transition in hydrogen atom
Replies: 2
Views: 31

Re: Energy Level transition in hydrogen atom

Frequency = -R [(1/n*2) - (1/N*2)]
in which "n" is the initial energy level, and "N" is the final energy level and we are supposed to solve for "n"

1.14x10^14 = -3.29x10^15 [(1/n^2) - (1/4^2)]

Solving for n, I ended up with n=6!
by Christine Honda 2I
Sat Oct 26, 2019 1:34 pm
Forum: Ionic & Covalent Bonds
Topic: Cation
Replies: 23
Views: 190

Re: Cation

As others have said, a cation loses electrons and anions gain electrons. Therefore, cations have a positive charge and anions have a negative charge.

My high school teacher told us to think that a cat has "paws" so therefore CATions are "pawsitive"
by Christine Honda 2I
Sun Oct 20, 2019 9:51 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Rules
Replies: 3
Views: 20

Re: Electron Configuration Rules

A completely full or half full d sub-level is more stable than a partially filled d sub-level, so an electron from the 4s orbital is excited and rises to a 3d orbital. It is easier for them to remove a 4s electron and bring it to the 3d subshell, which will give them a half-filled or completely fill...
by Christine Honda 2I
Sun Oct 20, 2019 9:50 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 7
Views: 76

Re: Atomic Radius

You can calculate it using the distance between two nuclei of touching identical atoms, but as far as trends for atomic radius,
The size of an atom will decrease as you move from left to the right of a period.
The radius of atoms increases as you go down a certain group.
by Christine Honda 2I
Sun Oct 20, 2019 9:46 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Ground State
Replies: 5
Views: 41

Re: Ground State

In a ground-state atom, all electrons are in the lowest possible energy levels.
by Christine Honda 2I
Sun Oct 20, 2019 9:45 pm
Forum: Quantum Numbers and The H-Atom
Topic: Balmer and Lyman Series
Replies: 6
Views: 52

Re: Balmer and Lyman Series

They both apply to the Hydrogen atom. Emission or absorption processes in hydrogen give rise to series, which are sequences of lines corresponding to atomic transitions, each ending or beginning with the same atomic state in hydrogen. For the Lyman series, which corresponds to UV light, the electron...
by Christine Honda 2I
Sun Oct 20, 2019 9:39 pm
Forum: Photoelectric Effect
Topic: 1B.3
Replies: 3
Views: 38

Re: 1B.3

In the photoelectric experiment, a certain light was used to attempt to eject an electron from a metal. The experiment showed that if the light were a wave, then simply increasing the intensity would increase energy. But, increasing the intensity of the light did not result in ejection. Scientists t...
by Christine Honda 2I
Sun Oct 20, 2019 8:43 pm
Forum: Einstein Equation
Topic: 1B.9 help
Replies: 4
Views: 36

Re: 1B.9 help

You need to convert nm to m then use the equation: E=hc/lambda. E = [(6.626 x 10^-34 Js)(3.0 x 10^8 m/s)]/(420 x 10^-9 m) = 4.7 x 10^-19 J Doing this gives us how much energy in Joules each photon has. Then multiply 32 W by 2, so 64 J are generated in 2.0 seconds. Use the answer we found above to ge...
by Christine Honda 2I
Sun Oct 20, 2019 8:35 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Exceptions to Orbital Rules
Replies: 8
Views: 63

Re: Exceptions to Orbital Rules

The two main exceptions are Chromium ([Ar]3d^5 4s^1) and Copper ([Ar] 3d^10 4s^1) These are exceptions to the general rule because a completely full or half full d sub-level is more stable than a partially filled d sub-level, so an electron from the 4s orbital is excited and rises to a 3d orbital. I...
by Christine Honda 2I
Sun Oct 20, 2019 8:24 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D.21
Replies: 5
Views: 36

1D.21

1D.21 Write the subshell notation (3d, for instance) and the num- ber of orbitals having the following quantum numbers: (a) n=5, l=2;(b)n=1,l=0;(c)n=6,l=3;(d)n=2,l=1.

Hi, I thought I understood quantum numbers but I'm not exactly sure what this problem is asking so an explanation would be great.
by Christine Honda 2I
Sun Oct 20, 2019 8:08 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Problem 1E.25
Replies: 2
Views: 24

Re: Problem 1E.25

Hi, can you explain the answer to part d) about the coinage metals being (n-1)d^10 ns^1

Is there any specific reason these are exceptions to the pattern of ground state configurations?
by Christine Honda 2I
Sun Oct 20, 2019 8:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Advice for studying
Replies: 58
Views: 548

Re: Advice for studying

I've found it helpful to watch the video modules and going over the practice problems. Sometimes I find the book confusing.
by Christine Honda 2I
Sun Oct 13, 2019 5:13 pm
Forum: Properties of Electrons
Topic: Equations for electrons
Replies: 4
Views: 22

Re: Equations for electrons

Yes, you are supposed to use equations that include wavelengths because of the wave-particle duality of light.
by Christine Honda 2I
Sun Oct 13, 2019 4:48 pm
Forum: Properties of Light
Topic: Quanta
Replies: 4
Views: 46

Re: Quanta

A photon is a quanta, but not all quanta are photons. This is similar to all squares are rectangles but not all rectangles are squares. "A photon is the quantum of electromagnetic radiation. The term quantum is the smallest elemental unit of a quantity, or the smallest discrete amount of someth...
by Christine Honda 2I
Sun Oct 13, 2019 4:41 pm
Forum: DeBroglie Equation
Topic: Self Test 1B.4B
Replies: 1
Views: 23

Re: Self Test 1B.4B

Using De Broglie's equation I plugged in the numbers:

(6.62 x 10^-34)/[(0.005)(686) = 1.93 x 10^-34 m
by Christine Honda 2I
Sun Oct 13, 2019 4:37 pm
Forum: Photoelectric Effect
Topic: HW Question 1B.3
Replies: 2
Views: 29

Re: HW Question 1B.3

In the photoelectric experiment, a certain light was used to attempt to eject an electron from a metal. The experiment showed that if the light were a wave, then simply increasing the intensity would increase energy. But, increasing the intensity of the light did not result in ejection. Scientists t...
by Christine Honda 2I
Sun Oct 13, 2019 4:27 pm
Forum: Photoelectric Effect
Topic: Estimating the uncertainty in the location or speed of a particle
Replies: 1
Views: 24

Re: Estimating the uncertainty in the location or speed of a particle

You will need to use a combined version of these two equations and E=hv and c=λv 1st we are given KeV units but we need to convert that to eV then to joules since energy is measured in joules. Kilo means 1000 of whatever unit is used. Therefore we multiply 140.511*10^3 Also the conversion factor for...
by Christine Honda 2I
Sun Oct 06, 2019 9:33 pm
Forum: Molarity, Solutions, Dilutions
Topic: G7
Replies: 2
Views: 29

G7

G.7 You need to prepare 510. g of an aqueous solution containing 5.45% KNO3 by mass. Describe how you would prepare the solution and what mass of each component you would use. I understand how to find the amount of KNO3 in the solution (27.6 grams). But what is the second part of the question asking...
by Christine Honda 2I
Sun Oct 06, 2019 9:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Specific type of calculator for tests?
Replies: 6
Views: 72

Re: Specific type of calculator for tests?

On the syllabus, it says that "Only non-programmable, non-graphing calculators are allowed."
by Christine Honda 2I
Sun Oct 06, 2019 9:17 pm
Forum: Limiting Reactant Calculations
Topic: Actual & Theoretical Yield
Replies: 4
Views: 26

Re: Actual & Theoretical Yield

Hi, in problems that ask for the percent yield they will typically give you the actual yield. To find the theoretical yield you have to find the limiting reactant and use that to find the theoretical yield of whatever product the question is asking for. Then you use the equation Percent Yield = Actu...
by Christine Honda 2I
Sun Oct 06, 2019 9:09 pm
Forum: Limiting Reactant Calculations
Topic: Determining Limiting Reactants
Replies: 2
Views: 46

Re: Determining Limiting Reactants

In my opinion, I think leaving it in moles is more helpful than converting it back to grams because of the extra unnecessary work. But when using the mole method, you have to remember the mole ratios and dividing by the stoichiometric coefficients to find the accurate moles needed for the reaction.
by Christine Honda 2I
Sun Oct 06, 2019 8:53 pm
Forum: SI Units, Unit Conversions
Topic: Homework Vs. Test
Replies: 3
Views: 68

Re: Homework Vs. Test

As the previous person said I think brushing up on the formulas before the test would be a good idea. Fundamentals Section D is super useful!
by Christine Honda 2I
Sun Oct 06, 2019 8:50 pm
Forum: SI Units, Unit Conversions
Topic: Peer Learning [ENDORSED]
Replies: 2
Views: 43

Re: Peer Learning [ENDORSED]

I went to a Workshop today! It was very helpful as the UA gave us a worksheet and we worked through the problems as a group. She gave many tips and explained the concepts very well. I plan on going to another Workshop and even a Step-Up session as well to reinforce these ideas. As the previous perso...
by Christine Honda 2I
Sun Oct 06, 2019 8:46 pm
Forum: SI Units, Unit Conversions
Topic: Naming Compounds?
Replies: 10
Views: 206

Re: Naming Compounds?

Even though this for this test you may not have to name compounds, Fundamentals D in the textbook is very helpful. I think it would be a good idea to look over it!

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