Search found 47 matches

by Marty Hockey
Fri Dec 06, 2019 3:40 pm
Forum: Administrative Questions and Class Announcements
Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
Replies: 111
Views: 4882

Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]

For number 20 how do we know whether the expected geometry of the compound is square planar or tetrahedral?
by Marty Hockey
Tue Dec 03, 2019 2:41 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 9c.5
Replies: 1
Views: 44

9c.5

Can anyone explain why in 9c.5, b) is monodentate or bidentate but in d) it is only bidentate? Both have double bonded oxygens so I don't understand why d) would not also be either monodentate or bidentate.
by Marty Hockey
Sun Dec 01, 2019 9:06 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Notes
Replies: 3
Views: 49

Notes

I was absent from lecture the day before thanksgiving and was hoping someone could tell me which topics were covered in that lecture. Thank you
by Marty Hockey
Sun Dec 01, 2019 9:03 pm
Forum: Naming
Topic: Memorizing ligand names
Replies: 5
Views: 53

Re: Memorizing ligand names

The only information we will have on the final will be the same equation sheet we have had for the previous exams, and there is no ligand naming sheet on it so it is extremely unlikely one would be provided.
by Marty Hockey
Sun Dec 01, 2019 9:02 pm
Forum: Naming
Topic: -bis, -tris, etc
Replies: 5
Views: 71

Re: -bis, -tris, etc

You use bis, tris, etc. when there is a greek prefix already in the name such as the di in ethylenediamine which is one of the examples we could see on the final.
by Marty Hockey
Sun Dec 01, 2019 4:10 pm
Forum: Naming
Topic: Roman numerals
Replies: 6
Views: 50

Roman numerals

For naming compounds, how am I supposed to know which roman numeral to use for the metal atom/ion?
by Marty Hockey
Wed Nov 20, 2019 11:46 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Best Approach to Find IMFs
Replies: 11
Views: 158

Re: Best Approach to Find IMFs

I would start out drawing the Lewis structure because that will determine whether or not a molecule is polar and capable of a hydrogen bond. If you draw it out and it is not symmetrical you know it is polar, and if it has an OH, NH, or HF bond than you know it is capable of a hydrogen bond. If anyon...
by Marty Hockey
Wed Nov 20, 2019 11:43 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: Homework 3F1
Replies: 4
Views: 65

Re: Homework 3F1

It is asking what kind of interactions these molecules could potentially have. NH2OH, for example, can have hydrogen bonds, dipole-dipole interactions, and London forces because it has an OH bond and is polar. CBr4 can only have London forces because it is nonpolar, and SO2 can have London and dipol...
by Marty Hockey
Wed Nov 20, 2019 11:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 6
Views: 70

Re: Bond Angles

Yes, for example, SO2 is angular with one lone pair so its angles are slightly less than 120 degrees.
by Marty Hockey
Wed Nov 20, 2019 11:37 pm
Forum: Dipole Moments
Topic: Intermolecular Forces
Replies: 7
Views: 85

Re: Intermolecular Forces

You can determine whether or not a molecule is capable of hydrogen bonds based on if it has an OH, HF, or NF bond or not as is the case for 3f1a, it is London forces for b) because it is nonpolar so it can't be a dipole, and it can have a dipole-dipole moment for d) because it is polar. Hope this he...
by Marty Hockey
Wed Nov 20, 2019 11:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle of bent
Replies: 17
Views: 151

Re: Bond Angle of bent

Less than 120 degrees if the molecule has one lone pair, and less than 109.5 degrees it the molecule has two lone pairs.
by Marty Hockey
Wed Nov 20, 2019 1:52 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: 3F
Replies: 1
Views: 46

3F

For Test 2 are we being tested on all different parts of 3F, of only 3.4 and 3.5?
by Marty Hockey
Mon Nov 18, 2019 12:09 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Biological activity
Replies: 2
Views: 37

Biological activity

Dr. Lavelle mentioned in the lecture that the shape and conformation of molecules often determine its biological activity, but I'm confused as to in what way does it determine biological activity?
by Marty Hockey
Mon Nov 18, 2019 12:07 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 6
Views: 66

Test 2

Can anyone reply with the subjects that are being covered on test 2? I'm confused about whether it is cumulative and if not, what specific topics it is covering.
by Marty Hockey
Mon Nov 18, 2019 12:01 am
Forum: Determining Molecular Shape (VSEPR)
Topic: polar vs non polar
Replies: 6
Views: 67

Re: polar vs non polar

Often times you can determine if the molecule is polar or non-polar by examining the symmetry of the molecule to see if they cancel out. If it is not apparent that they cancel out through symmetry calculations should ensue.
by Marty Hockey
Sun Nov 17, 2019 11:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion strength
Replies: 5
Views: 50

Re: Repulsion strength

Repulsion is stronger when electrons are closer and weaker when they are further apart.
by Marty Hockey
Sun Nov 17, 2019 11:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: electronegativity
Replies: 6
Views: 53

Re: electronegativity

Electronegativity for a molecule is determined by the difference between the electronegativity of the different atoms. For example, H has an electronegativity of 2.1 and F has an electronegativity of 4.0, so 4.0 - 2.1 = 1.9. HF, therefore, has an electronegativity of 1.9.
by Marty Hockey
Mon Nov 11, 2019 7:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorization Tips
Replies: 3
Views: 58

Memorization Tips

Does anyone have any recommendations/tips on the best ways to memorize all of the different shapes and angles we need to know for molecular shape?
by Marty Hockey
Mon Nov 11, 2019 6:58 pm
Forum: Electronegativity
Topic: Formula for Difference
Replies: 7
Views: 167

Re: Formula for Difference

You should know the various trends and understand the exceptions (the column of oxygen) but you do not need to know the electronegativity values of each element.
by Marty Hockey
Tue Nov 05, 2019 7:53 pm
Forum: Photoelectric Effect
Topic: Wavelength to Frequency
Replies: 3
Views: 153

Re: Wavelength to Frequency

Sorry I should have clarified, this is for an electron not light.
by Marty Hockey
Tue Nov 05, 2019 7:40 pm
Forum: Photoelectric Effect
Topic: Wavelength to Frequency
Replies: 3
Views: 153

Wavelength to Frequency

Hello, can anyone tell me the steps to go from a given wavelength and work function to frequency?
by Marty Hockey
Sun Nov 03, 2019 4:32 pm
Forum: Lewis Structures
Topic: Bonds
Replies: 1
Views: 28

Bonds

In what situations are atoms allowed to have more than 8 electrons? For example, there have been problems in which an element has four shared bonds and an additional lone pair.
by Marty Hockey
Sun Nov 03, 2019 4:28 pm
Forum: DeBroglie Equation
Topic: When to use the DeBroglie equation?
Replies: 6
Views: 77

Re: When to use the DeBroglie equation?

Anytime a problem gives you any of the following: frequency, wavelength, energy, mass, frequency, or the velocity of light and asks you to find a different term in the aforementioned list is when you would use the equation.
by Marty Hockey
Sun Nov 03, 2019 4:19 pm
Forum: DeBroglie Equation
Topic: unit of wavelength
Replies: 5
Views: 186

Re: unit of wavelength

The unit is in meters but is often extremely small so it is expressed in nanometers. For example, you would be given a wavelength of 1.5 x 10^-9 meters which could otherwise be written as 1.5 nm.
by Marty Hockey
Sun Nov 03, 2019 4:17 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polarizing power
Replies: 3
Views: 39

Re: polarizing power

The larger the radius of the element, the larger the polarizing power. So K would have higher polarizing power than Na, and then Na would have higher polarizing power than Li. The trend for the atomic radius is increasing as you go down a period and decreasing as you go across a row.
by Marty Hockey
Sun Nov 03, 2019 4:12 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy of Group 16
Replies: 3
Views: 34

Re: Ionization Energy of Group 16

Terelium and polonium have higher first ionization energies than the elements next to them in group 15, but oxygen, sulfur, and selenium all have lower ionization energies than the elements to their left in group 15. This is because group 16 is the first time that there is a paired electron in the p...
by Marty Hockey
Sun Oct 27, 2019 10:37 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance Structures
Replies: 5
Views: 47

Resonance Structures

When I am drawing Lewis structures such as NO3^-1, am I allowed to have a bar line that signals two electrons on the oxygen instead of two dots, or does it always have to be the two dots? It's faster and less tedious.
by Marty Hockey
Sun Oct 27, 2019 10:33 pm
Forum: Lewis Structures
Topic: Formal Charge [ENDORSED]
Replies: 6
Views: 79

Re: Formal Charge [ENDORSED]

The formal charge of an atom indicates gain or loss of electrons while forming a covalent bond. To determine formal charge, count the number of shared electrons (s), count each number of lone pair electron (L) and then follow the formula: FC (formal charge) = V (valence electrons) - (L + s/2)
by Marty Hockey
Sun Oct 27, 2019 10:30 pm
Forum: Ionic & Covalent Bonds
Topic: 2A. 9
Replies: 2
Views: 36

Re: 2A. 9

Essentially all you need to do is follow the electron configuration to the according element. So |Ar|3d7 would take you to the row following Argon (the 4th row) and since it is only 3d7 you just need to count 7 elements from the furthest d point which would be from Scandium to Cobalt, leaving you wi...
by Marty Hockey
Sun Oct 27, 2019 10:27 pm
Forum: Ionic & Covalent Bonds
Topic: 2A. 5 part b & d
Replies: 1
Views: 35

Re: 2A. 5 part b & d

Bi +3: The previous noble gas for Bi is Xenon so it starts out with |Xe| and then because it is in the 6th row we have to factor in the 4f column so the next sequence is |Xe|4f^14, following that we factor in the next d row as we normally would so |Xe|4f145d10, and then we add in the 6s as that is t...
by Marty Hockey
Sun Oct 27, 2019 10:17 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy Unit
Replies: 6
Views: 65

Re: Ionization Energy Unit

The units are kj/m or kilojoules per mole, or electron volts
by Marty Hockey
Sat Oct 19, 2019 7:54 pm
Forum: Properties of Electrons
Topic: Electron structures
Replies: 2
Views: 49

Electron structures

When filling the spins of electrons in a problem, for example filling the p shell, does it matter which spaces have arrows first? I know that you have to fill the 3 spaces before being allowed to add a second arrow, but does it matter which space you would put the 4th arrow in?
by Marty Hockey
Sat Oct 19, 2019 7:53 pm
Forum: Properties of Electrons
Topic: Electron structures
Replies: 2
Views: 40

Electron structures

When filling the spins of electrons in a problem, for example filling the p shell, does it matter which spaces have arrows first? I know that you have to fill the 3 spaces before being allowed to add a second arrow, but does it matter which space you would put the 4th arrow in?
by Marty Hockey
Sat Oct 19, 2019 7:49 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: P Orbital specifics
Replies: 4
Views: 45

Re: P Orbital specifics

I understand that if there were more than one electron in an orbital they would need to be in separate orbitals, but is the determination of which orbital the electron falls into arbitrary? As in could the first electron fill 2pz, the second 2px, or really any order as long as they're in different o...
by Marty Hockey
Sat Oct 19, 2019 7:45 pm
Forum: Properties of Electrons
Topic: Building Up
Replies: 2
Views: 44

Building Up

What is the purpose of writing the electron structure of carbon as 1s^2 2s^2 2px^1 2py^1 as opposed to 1s^2 2s^2 2p^2?
by Marty Hockey
Sat Oct 19, 2019 7:41 pm
Forum: Properties of Electrons
Topic: Conceptual vs. problem
Replies: 2
Views: 46

Conceptual vs. problem

Does anyone know if we are supposed to have knowledge of how a lot of the equations we use (De Broglie, Rydberg, etc.) were derived?
by Marty Hockey
Sat Oct 19, 2019 7:37 pm
Forum: Properties of Electrons
Topic: Electron structures
Replies: 4
Views: 72

Electron structures

I understand that if 2 electrons are paired they have opposite spin, and if they're parallel they have the same spin, but what makes the electrons paired or parallel?
by Marty Hockey
Sun Oct 13, 2019 8:19 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: HW question 1A.11
Replies: 1
Views: 40

Re: HW question 1A.11

I believe the group comes from an electron making a transition between two energy levels in an atom.
by Marty Hockey
Sun Oct 13, 2019 7:47 pm
Forum: DeBroglie Equation
Topic: DeBroglie Equation
Replies: 9
Views: 130

Re: DeBroglie Equation

When using the DeBroglie equation, do the units for mass have to be in grams, and does the velocity have to be in meters per second?
by Marty Hockey
Sun Oct 13, 2019 7:35 pm
Forum: DeBroglie Equation
Topic: Wavelength
Replies: 6
Views: 84

Re: Wavelength

What is the equation used to determine the wavelength of gamma rays? Used for problem 1B.5
by Marty Hockey
Fri Oct 11, 2019 12:24 pm
Forum: Properties of Light
Topic: Homework Question 1A.3
Replies: 3
Views: 61

Re: Homework Question 1A.3

The reason the answer is C is that to cause a change in the electrical field you need a sufficient amount of energy to cause this change. When you decrease the frequency you are decreasing the energy and thus making it more difficult to cause change so there is either less change or no change at all...
by Marty Hockey
Fri Oct 11, 2019 12:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Posts
Replies: 6
Views: 83

Re: Posts

What I've found helpful so far has been writing down or taking note of any questions I have as I'm going through problems. Anytime I have a hiccup or even slight confusion whether it be in lecture or homework, I try to make a note of it so that I can ask for clarification later on down the line. Thi...
by Marty Hockey
Sun Oct 06, 2019 8:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Posts
Replies: 6
Views: 83

Posts

Hello just wondering what day of the week are we supposed to have had 5 posts written on chemistry community? Additionally, are we shifting to turning in homework during discussion or are we going to continue turning them in after lecture on Friday? Thanks.
by Marty Hockey
Sun Oct 06, 2019 7:57 pm
Forum: Properties of Light
Topic: Incident Light
Replies: 2
Views: 24

Re: Incident Light

Incident light can be reflected, absorbed, or transmitted through a sample. The way the incident light changes during an interaction with a sample is characteristic of the substance and can be measured by a spectrometer.
by Marty Hockey
Sun Oct 06, 2019 7:50 pm
Forum: General Science Questions
Topic: Avogadro’s Number, The Mole
Replies: 1
Views: 56

Re: Avogadro’s Number, The Mole

Before the 1960s, the standard of measurement for a mole was based on Oxygen. Developments in mass spectrometry allowed scientists to find the number of atoms in 12 grams of carbon. In 2018 at a science conference in France they decided that one mole of a substance would be redefined as "6.022 ...
by Marty Hockey
Sun Oct 06, 2019 6:56 pm
Forum: General Science Questions
Topic: temperature
Replies: 4
Views: 108

Re: temperature

K = C + 273.15
by Marty Hockey
Sun Oct 06, 2019 6:52 pm
Forum: General Science Questions
Topic: Molar Mass
Replies: 1
Views: 45

Re: Molar Mass

Molar mass is the mass of one mole of an element while atomic mass is the mass of an atom at rest. However, the mass number on the periodic table is both the atomic weight and molar mass for elements (the molar mass and atomic weight of carbon is 12.011g/mol).

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