Search found 33 matches

by Krisdylle Repollo 4H
Fri Dec 07, 2018 9:18 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 11
Views: 289

Re: Polydentate

If the ligand has more than one binding site, then it is considered a polydentate.
by Krisdylle Repollo 4H
Fri Dec 07, 2018 9:16 pm
Forum: Naming
Topic: naming
Replies: 5
Views: 160

Re: naming

I think it's helpful to just memorize the oxidation states of the molecules that we've been practicing during the lectures because they'll most likely pop up during the exam at some point and it'll be helpful if you know it right away. But if you don't, you can always try doing the Lewis structure. ...
by Krisdylle Repollo 4H
Fri Dec 07, 2018 9:08 pm
Forum: General Science Questions
Topic: hydrogen bonding
Replies: 3
Views: 287

Re: hydrogen bonding

Yes, hydrogen bonding can only occur if it is bonding to an O, N, or F. And yeah if not bonded to any of these then it would be a dipole-dipole force. (Ex. HBr --- HBr)
by Krisdylle Repollo 4H
Sun Dec 02, 2018 5:29 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Bases
Replies: 4
Views: 214

Re: Bases

The alkali in the base makes it feel soapy. I think Professor Lavelle gave an example during class like if you run your hands under water but it still feels soapy (even though you're not using soap) it's because of the alkali in the water.
by Krisdylle Repollo 4H
Sun Dec 02, 2018 5:16 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: Non-polar
Replies: 1
Views: 67

Re: Non-polar

Yes because a polar molecule by definition is an atom that shares electrons, making one side of the atom more negative (due to the electron density on that side) and the other side more positive, causing a dipole moment. A non-polar molecule would be exactly opposite, meaning there are no separation...
by Krisdylle Repollo 4H
Sun Dec 02, 2018 5:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 4
Views: 127

Re: VSEPR

Well one of those three atoms would have to be the central atom (A) so technically the VSEPR formula would be AX2E. (A = central atom, X = atoms attached to central atom.)
by Krisdylle Repollo 4H
Sun Nov 25, 2018 6:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape of (CH3)2Be
Replies: 1
Views: 53

Molecular Shape of (CH3)2Be

4.19 Predict the shapes and estimate the bond angles of (a) the thiosulfate ion, S2O32; (b) (CH3)2Be; (c) BH2; (d) SnCl2. For part B, the solutions manuals says that the shape is tetrahedral about the carbon atoms. Is there a reason as to why it is specific to the carbon atoms? Does it have somethin...
by Krisdylle Repollo 4H
Sun Nov 25, 2018 6:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3 material
Replies: 6
Views: 185

Re: Test 3 material

If you look at the announcements on his website, it says that test three will cover up until 3.12 from the 6th edition and 2D from the 7th edition, so up until ionic and covalent bonds and all of molecular shape and structure (4.1-4.7 in the 6th edition and 2E-F in the 7th edition).
by Krisdylle Repollo 4H
Sun Nov 25, 2018 6:23 pm
Forum: Octet Exceptions
Topic: How do we know if an element can have an expanded octet?
Replies: 3
Views: 265

Re: How do we know if an element can have an expanded octet?

Yes, elements in period three and beyond have access to their d-orbitals which allow them to have more than 8 electrons on their valence shell (the d-orbital can hold 10 electrons).
by Krisdylle Repollo 4H
Sun Nov 18, 2018 6:34 pm
Forum: Bond Lengths & Energies
Topic: VSEPR Model Question
Replies: 2
Views: 89

VSEPR Model Question

Can someone explain why the electron geometry for the ONF is trigonal planar and not linear? There are two bonding regions in the Lewis structure and according to the lecture, two bonding regions will create a linear structure.
by Krisdylle Repollo 4H
Sun Nov 18, 2018 6:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Geometry (Drawing)
Replies: 2
Views: 94

Re: Molecular Geometry (Drawing)

The TAs said that we won't be drawing in the next test, but it helps to know the model so you know what shape your molecule will turn out to be.
by Krisdylle Repollo 4H
Sun Nov 18, 2018 6:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Geometry
Replies: 6
Views: 127

Re: Molecular Geometry

Molecular geometry is used to describe the actual shape of the molecule given. Electron geometry is specific to the electron pairs or groups in relation to the central atom; it's basically the geometry of the electrons in a molecule.
by Krisdylle Repollo 4H
Sun Nov 11, 2018 8:55 pm
Forum: Electronegativity
Topic: Question 3.79 (Sixth Edition)
Replies: 1
Views: 72

Re: Question 3.79 (Sixth Edition)

If the difference in electronegativity between the two atoms is more than 1.5, it is an ionic bond. Ionic bonds tend to be more soluble in water because when the ions interact with the water molecules, the energy given off is equal to the amount of energy that is needed to break that ionic bond and ...
by Krisdylle Repollo 4H
Sun Nov 11, 2018 8:50 pm
Forum: Octet Exceptions
Topic: learning octet excptions
Replies: 4
Views: 116

Re: learning octet excptions

Octet exceptions are usually for atoms who have access to their d subshell. I would suggest looking to see if the central atom in your molecule can access it and if it does then that atom can have 10 electrons instead of fulfilling the octet.
by Krisdylle Repollo 4H
Sun Nov 11, 2018 8:47 pm
Forum: Dipole Moments
Topic: Interaction Potential Energy
Replies: 1
Views: 85

Interaction Potential Energy

Equation: E(p) = - [(q1*q2)/ r^6]

Why is this equation always negative?
by Krisdylle Repollo 4H
Sun Nov 11, 2018 8:42 pm
Forum: Lewis Structures
Topic: VSEPR Model
Replies: 1
Views: 79

VSEPR Model

Can someone please explain what Professor Lavelle meant during the lecture when he talked about the repulsion strengths in VSEPR models? I wrote down lone-lone pair > lone-bonding pair > bonding-bonding pair in regards to repulsion strength. Where would I see these bonding pairs on a VSEPR model?
by Krisdylle Repollo 4H
Sun Nov 04, 2018 1:51 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 3
Views: 84

Re: Formal Charge

I think it was mentioned in the review sessions that the only way to determine which Lewis Structure is the most accurate is to find the formal charges of each atom. By finding the formal charges of each structure, the best one would be where the charges are closest to zero.
by Krisdylle Repollo 4H
Sun Nov 04, 2018 1:44 pm
Forum: SI Units, Unit Conversions
Topic: Significant Figures during Multiple Step Calculations
Replies: 2
Views: 242

Re: Significant Figures during Multiple Step Calculations

Yup, it's okay to use multiple digits in your calculations but just make sure to write your overall answer with the correct number of sig figs.
by Krisdylle Repollo 4H
Fri Nov 02, 2018 10:37 am
Forum: Photoelectric Effect
Topic: Photoelectric Experiment - Chem Test 2
Replies: 3
Views: 192

Photoelectric Experiment - Chem Test 2

4. In an X-ray photoelectron experiment, lead metal is irradiated with X-ray light. Part A: The intensity of ejected electrons is plotted as a function of their velocity, as shown in the graph below. Calculate the total kinetic energy in 5 mol of ejected electrons. What does it mean by “5 mol of eje...
by Krisdylle Repollo 4H
Sun Oct 28, 2018 1:19 pm
Forum: Ionic & Covalent Bonds
Topic: ionization energy
Replies: 7
Views: 166

Re: ionization energy

This is because the more electrons you take away from an atom, the stronger the attraction between the nucleus and the remaining electrons are. The atom then becomes positive which leads to a greater energy needed to remove the next electron from the atom.
by Krisdylle Repollo 4H
Sun Oct 28, 2018 1:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: F-block elements
Replies: 1
Views: 64

F-block elements

I'm having trouble figuring out the electron configurations of the f-block elements. For example, the electron configuration for thorium is Rn6d^27s^2, but the atom is in the f-block of the periodic table. Why are the orbitals only d and s but not f? Is there a separate rule regarding the f-block el...
by Krisdylle Repollo 4H
Sun Oct 28, 2018 12:47 pm
Forum: Trends in The Periodic Table
Topic: Inert Pair
Replies: 1
Views: 76

Re: Inert Pair

A pair of low energy s-valence electrons would be harder to remove during ion formation because that atom would have a higher ionization energy than the atom with only on low energy s-valence electron. Remember that ionization energy of atoms increases across a period, meaning that the attraction be...
by Krisdylle Repollo 4H
Sat Oct 20, 2018 3:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Multi electron atoms
Replies: 5
Views: 112

Re: Multi electron atoms

This equation is known as the electrostatic potential energy of two charges. It is the energy needed to move a charge against its electrical field, in this case, the charge of the particles you are working with.
by Krisdylle Repollo 4H
Sat Oct 20, 2018 3:21 pm
Forum: Properties of Light
Topic: 3 Posts on Chemistry Community [ENDORSED]
Replies: 5
Views: 115

Re: 3 Posts on Chemistry Community [ENDORSED]

I believe the deadline is Sunday, that's what some of the TA's have said at least.
by Krisdylle Repollo 4H
Sat Oct 20, 2018 3:19 pm
Forum: Properties of Light
Topic: Atomic Spectra
Replies: 1
Views: 52

Re: Atomic Spectra

Well, first you would have to find the frequency using the equation v(nu) = c/ λ. and that would give you 2.922 x 10-15 s-1. Then you would have to use Rydberg's equation to solve for n2.
by Krisdylle Repollo 4H
Sat Oct 20, 2018 2:37 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Complementarity of Location and Momentum
Replies: 1
Views: 43

Re: Complementarity of Location and Momentum

I think during lecture, Professor Lavelle mentioned that when photons interact with electrons, this interaction will affect the position AND momentum of the electron, so the momentum would not be precisely known. Because we don't know the pathway of the electron, the velocity would change therefore ...
by Krisdylle Repollo 4H
Sun Oct 14, 2018 12:20 pm
Forum: Einstein Equation
Topic: 7th edition 1B. 7
Replies: 2
Views: 57

Re: 7th edition 1B. 7

And for part C, since you're already given 1 mol of Sodium atoms, you know that 1 mol equals 6.022 x 10^23 atoms/mol. So you multiply this number to the energy you found in part A to find your answer.
by Krisdylle Repollo 4H
Sun Oct 14, 2018 12:18 pm
Forum: Einstein Equation
Topic: 7th edition 1B. 7
Replies: 2
Views: 57

Re: 7th edition 1B. 7

For part B, you have to find the molar mass of sodium and multiply it by Avogrado's number and the energy you found in part A. So the equation would look like this: (5.00 x 10^-3 g Na/22.99 g•mol Na) x (6.022 x 10^23 atoms/mol) x (3.37 x 10^-19 J/atom) = 44.1 J The units cancel and you're left with ...
by Krisdylle Repollo 4H
Wed Oct 10, 2018 7:26 pm
Forum: Properties of Light
Topic: Problem 1.23
Replies: 2
Views: 45

Problem 1.23

1.23 The ray photons emitted by the nuclear decay of a technetium-99 atom used in radio pharmaceuticals have an energy of 140.511 keV. Calculate the wavelength of these rays. During the lecture, Professor Lavelle gave us Planck's constant as h= 6.63 x 10-34 Js. But the solutions manual uses the numb...
by Krisdylle Repollo 4H
Wed Oct 10, 2018 5:45 pm
Forum: Limiting Reactant Calculations
Topic: Question M.5 (Sixth Edition)
Replies: 2
Views: 145

Re: Question M.5 (Sixth Edition)

The problem already gives you the amount of moles of each reactant (12 mol ClO2 and 5 mol BrF3). To determine the excess reactant, you can use one of moles of these reactants and multiply it by the stoichiometric coefficients in the reaction. For example: 12 mol ClO2 x (2 mol BrF3/6 mol ClO2) = 4 mo...
by Krisdylle Repollo 4H
Thu Oct 04, 2018 4:40 pm
Forum: Significant Figures
Topic: SIG FIGS in ratios
Replies: 4
Views: 219

Re: SIG FIGS in ratios

I'm not sure what Professor Lavelle would want in regards to sig figs in ratios, but in high school we were taught that sig figs would only be applied at the end when you find your answer. You can always use sig figs in your calculations though, because you'll most likely end up getting the same ans...
by Krisdylle Repollo 4H
Thu Oct 04, 2018 1:30 pm
Forum: Limiting Reactant Calculations
Topic: chemical formula regarding M.9
Replies: 2
Views: 92

Re: chemical formula regarding M.9

The roman numerals in Copper (II) just indicate the charge of the metal. Another way to see it is CU2+. We use roman numerals because some metals have more than one ion. In the case of copper, there are two; copper (I) (cuprous) and copper (II) (cupric).
by Krisdylle Repollo 4H
Wed Oct 03, 2018 1:25 pm
Forum: Limiting Reactant Calculations
Topic: Post-assessment problem, neutralizing acids
Replies: 2
Views: 83

Re: Post-assessment problem, neutralizing acids

In this question, you don’t need the mass of the acid and convert it into moles. The question is asking you to find how many moles of CO2 are produced after the reaction. If you take a look at the equation, you see that there is a 1:1 molar ratio therefore you know that 1 mole of CaCo3 produces 1 mo...

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