## Search found 87 matches

Tue Dec 01, 2020 2:00 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Focus Exercise 2.27
Replies: 4
Views: 14

### Re: Focus Exercise 2.27

I believe diamagnetic just means that there are no unpaired electrons
Tue Dec 01, 2020 1:57 pm
Forum: Sigma & Pi Bonds
Topic: Rotation
Replies: 9
Views: 32

### Re: Rotation

If a a pi bond is present that means that a sigma bond is also present.
Tue Dec 01, 2020 1:56 pm
Forum: Ionic & Covalent Bonds
Topic: Polar and Nonpolar
Replies: 17
Views: 34

### Re: Polar and Nonpolar

Drawing the shape of the molecule and the dipole moments will help because it will show if the dipole vectors cancel out.
Tue Dec 01, 2020 1:51 pm
Forum: Naming
Topic: Naming Coordination Compounds
Replies: 4
Views: 22

### Re: Naming Coordination Compounds

I think as long as we can name the ligands we used in class examples, in the sapling hw, and in the textbook problems, we will be fine.
Tue Dec 01, 2020 1:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 9
Views: 42

### Re: Ligands

Ligands attach to a transition metal in a coordinate covalent bond. If there are 6 ligands connected to the transition metal it is an octahedral Copley and if there are 4 ligands attached it is either tetrahedral or square planar complex.
Tue Dec 01, 2020 1:47 pm
Forum: Resonance Structures
Topic: Valence Electrons
Replies: 36
Views: 131

### Re: Valence Electrons

You can use the group number to determine the number of valence electrons or you can figure out the electron configuration but that takes a while.
Mon Nov 30, 2020 10:39 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles
Replies: 5
Views: 22

### Re: Bond angles

Can someone explain why the bond angles about the carbon atoms for the molecule (CH3)2Be are 109.5 degrees. Shouldn't it be less than 109.5 because Be pushes the H atoms further away from it than a H atom would?
Mon Nov 30, 2020 10:32 am
Forum: Electronegativity
Topic: Be vs Cl
Replies: 10
Views: 28

### Re: Be vs Cl

The elements closest to Fluorine have a higher electronegativity.
Fri Nov 27, 2020 9:55 am
Forum: Sigma & Pi Bonds
Topic: Perpendicular Pi Bonds
Replies: 2
Views: 19

### Re: Perpendicular Pi Bonds

I was also confused and still am, but the solution says molecules of this type can be explained by the formula H2CC(x)CH2 and if X is an odd number the H atoms at end of molecule will lie on perpendicular planes.
Thu Nov 26, 2020 9:58 am
Forum: Hybridization
Topic: Sapling Week 7 & 8 HW Question 11
Replies: 14
Views: 66

### Re: Sapling Week 7 & 8 HW Question 11

I just know that the hybridization numbers have to add up to the atomic orbitals and that s can only go to 1, p to 3, and d to 5. So if there are 5 atomic orbitals I know it is sp3d, because 1+3+1=5.

Sorry if this is confusing.
Thu Nov 26, 2020 9:54 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Coordination Compounds
Replies: 5
Views: 23

### Re: Coordination Compounds

I don't think there is a difference between an OH2 bond and an H20. We just write them different in the lewis structure to show that the cation and ions are binding to each other.
Thu Nov 26, 2020 9:47 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair Placement
Replies: 4
Views: 21

### Re: Lone Pair Placement

All 3 F's are not equatorial because that would result in a higher energy molecule because the two lone pairs would then have to be in the axial positions and they would be interacting with 3 atoms instead of just 2 atoms. If the molecule was octahedral with 2 lone pairs, then the lone pairs would b...
Thu Nov 26, 2020 9:41 am
Forum: Hybridization
Topic: Hybridization orbital
Replies: 2
Views: 10

### Re: Hybridization orbital

Don't forgot that the number of hybrid orbitals equals the number of atomic orbitals. Conservation of orbitals! So 2 atoms orbitals=2 hybrid orbitals
Thu Nov 26, 2020 9:38 am
Forum: Administrative Questions and Class Announcements
Topic: Tests
Replies: 4
Views: 44

### Re: Tests

I have the same problem with getting behind, I find that planning when I will do the hw and textbook problems ahead of time helps me keep on track for the midterm.
Thu Nov 26, 2020 9:34 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Atom Angles
Replies: 3
Views: 27

### Re: Atom Angles

They used rotation and vibrational spectroscopy, and X-ray diffraction to find the angles between the atoms in a molecule.
Sun Nov 22, 2020 5:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle of Molecule
Replies: 7
Views: 40

### Re: Bond Angle of Molecule

We know it would be less than 109.5 because that is the bond angle if all the atoms are the same, but since the atoms differ, we know that some atoms will be pushed closer together and have a smaller bond angle that we would have to determine experimentally. We would not be able to look at the shape...
Sun Nov 22, 2020 8:45 am
Forum: Student Social/Study Group
Topic: Study Tips for Final Exam
Replies: 57
Views: 217

### Re: Study Tips for Final Exam

I also go over all the problems we did in discussion because I have found those problems or similar ones always end up on the exam.
Sun Nov 22, 2020 8:43 am
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Model Memorization
Replies: 3
Views: 10

### Re: VSEPR Model Memorization

I don't think there is a quick way to memorize all of them, I think we just have to draw the lewis structure and determine the shape based off of the arrangement of the atoms.
Sun Nov 22, 2020 8:40 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: Helpful Summary of What Induced Dipole- Induced Dipole depends on
Replies: 6
Views: 61

### Re: Helpful Summary of What Induced Dipole- Induced Dipole depends on

Yuelai Feng 3E wrote:
Charlotte Adams 2D wrote:So if there are more electrons, is the induced-dipole induced-dipole stronger and harder to break?

Thanks

Yes you're right. But induced-dipole induced-dipole interactions are all very weak compared to other interactions.

thanks for clarifying!
Sun Nov 22, 2020 8:39 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Axial vs. Equatorial
Replies: 4
Views: 25

### Re: Axial vs. Equatorial

I think equatorial atoms exist on the equator or median of the plane, while axial are perpendicular.
Sun Nov 22, 2020 8:35 am
Forum: Formal Charge and Oxidation Numbers
Topic: Best Formal Charge Equations
Replies: 24
Views: 74

### Re: Best Formal Charge Equations

For formal charge, if I am in a hurry, I just count the lone pair electrons and then one electron for each bond pair and if it gained an electron I know it is -1 and if it lost an electron I know it is +1. So for a single bonded oxygen I count the 6 lone pair electrons and the 1 electron from the bo...
Mon Nov 16, 2020 10:03 am
Forum: Electronegativity
Topic: Homework Problem 3F.19
Replies: 4
Views: 25

### Re: Homework Problem 3F.19

Just curious, did this question show the lewis structure of pentane and diethyl ether. I don't know if I would be able to tell which is more rod-shaped just based off the formulas.

Thanks!
Mon Nov 16, 2020 10:00 am
Forum: Administrative Questions and Class Announcements
Topic: Matthew's Workshop - Week 6
Replies: 2
Views: 212

### Re: Matthew's Workshop - Week 6

Hi! I was not able to attend this session but did some of the questions on the worksheet. For the last question I got that 8 hydrogen bonds could be formed from Guanine, is this correct?

Thanks!
Mon Nov 16, 2020 9:56 am
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 5
Views: 34

### Re: Bond Length

When doing the Sapling, if the length of the bond was closer to that of double bonds, the answer was that it had more double bonds.
Mon Nov 16, 2020 9:55 am
Forum: Dipole Moments
Topic: Difference between Dipole-Induced Dipole vs LDF/Van der Waals/Induced dipole-Induced dipole
Replies: 6
Views: 37

### Re: Difference between Dipole-Induced Dipole vs LDF/Van der Waals/Induced dipole-Induced dipole

Hi! I was just wondering if dipole-induced dipole intermolecular forces are different from London dispersion forces (and the other names it goes by). When I was in high school, my chem teacher grouped them together. Just to clarify, dipole-induced dipole IMFs are between a molecule with a permanent ...
Mon Nov 16, 2020 9:51 am
Forum: Lewis Structures
Topic: textbook problem 2C.13: ClO2
Replies: 3
Views: 9

### Re: textbook problem 2C.13: ClO2

After looking at the problem I see that CLO2 has no charge, I believe the CL is the radical because the oxygens will be filled before chlorine because oxygen is more electronegative than Cl.

Hope this helps!
Mon Nov 16, 2020 9:49 am
Forum: Lewis Structures
Topic: textbook problem 2C.13: ClO2
Replies: 3
Views: 9

### Re: textbook problem 2C.13: ClO2

Hi! Im pretty sure CLO2 is an anion with a negative 1 charge, so there would actually be 20 electrons in total.
Mon Nov 16, 2020 9:46 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: dipole moments
Replies: 10
Views: 35

### Re: dipole moments

I went to Johnathan's step-up and he gave us a little trick: the side of the arrow with the dashed line looks like a plus sign so you draw the plus sign end on the positive particle charge and draw the arrowhead toward the negative partial charge. Also, I just remember electrons are moving toward th...
Sun Nov 15, 2020 11:31 am
Forum: Ionic & Covalent Bonds
Topic: Sapling question
Replies: 3
Views: 40

### Re: Sapling question

In this case, BCl3, Br2, and C2H6 would display only London dispersion forces. BCl3 is symmetric in shape, and its "vectors" (regions of charge) cancel out (pointing in opposite directions), thus is nonpolar and has only london dispersion forces. Although NF3 also looks like a good option...
Sun Nov 15, 2020 11:09 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: H-F H-F Hydrogen Bonding vs Dipole-Dipole
Replies: 11
Views: 51

### Re: H-F H-F Hydrogen Bonding vs Dipole-Dipole

Izamary Marquez 2L wrote:In addition, when calculated a dipole moment, will |q| always be given?

I don't think we will have to calculate the dipole for the test.
Sun Nov 15, 2020 11:08 am
Forum: Lewis Structures
Topic: Cl Breaking Octet
Replies: 2
Views: 15

### Re: Cl Breaking Octet

I believe it can accommodate 10, 12 or more electrons because of its empty d-orbitals. So far I have not seen a problem in which the central atom is accommodating more than 12 valence electron.
Sun Nov 15, 2020 11:05 am
Forum: Dipole Moments
Topic: Dipole or Ion
Replies: 4
Views: 23

### Re: Dipole or Ion

You are correct, dipole is used to describe a covalent bond in which there are nonzero partial charges.
Fri Nov 13, 2020 4:47 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: Helpful Summary of What Induced Dipole- Induced Dipole depends on
Replies: 6
Views: 61

### Re: Helpful Summary of What Induced Dipole- Induced Dipole depends on

So if there are more electrons, is the induced-dipole induced-dipole stronger and harder to break?

Thanks
Fri Nov 13, 2020 4:43 pm
Forum: Ionic & Covalent Bonds
Topic: Sapling question
Replies: 3
Views: 40

### Sapling question

Can somebody explain what the answer is to the following sapling question is and why Which molecules exhibit only London (dispersion) forces? NF3 Br2 CH3Cl BCl3 C2H6 I know that Br2 will only experience London interactions because it is non-polar but I am not sure how to determine if some of the oth...
Fri Nov 13, 2020 4:39 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizable vs. Polarizability
Replies: 5
Views: 35

### Re: Polarizable vs. Polarizability

Polarizability of an atom refers to how easily the electron cloud can be distorted and it is referring to anions because the electrons are being distorted. Polarizing power is the ability of the cation to distort the anion. A small and highly charged atom has a high polarizing power because it has a...
Fri Nov 13, 2020 4:34 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: H-F H-F Hydrogen Bonding vs Dipole-Dipole
Replies: 11
Views: 51

### Re: H-F H-F Hydrogen Bonding vs Dipole-Dipole

I am also confused because we in the HW we were shown an H-F bonding to another H-F and it said the intermolecular force shown was hydrogen bonding.
Fri Nov 13, 2020 4:32 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence electrons in d orbital ?
Replies: 3
Views: 15

### Re: Valence electrons in d orbital ?

I was also confused by this because when we write the electron configuration for elements in the p-block in period 4 we include 3d, but I believe we just count the outermost electrons as valence electrons. So, carbon has 4 valence electrons, Oxygen has 6...
Thu Nov 12, 2020 8:11 am
Forum: Lewis Structures
Replies: 12
Views: 36

Radicals are species with unpaired electrons, like a methyl group. There are also biradicals that have 2 unpaired electrons on either the same or different atom.
Thu Nov 12, 2020 8:05 am
Forum: General Science Questions
Topic: Which would have lower ionization energy?
Replies: 13
Views: 59

### Re: Which would have lower ionization energy?

Chlorine would have a lower ionization energy because the valence electrons are in a higher shell and thus they are not as compact as the valence electrons in Oxygen. The ionization energy also increases across the period because of a higher effective nuclear charge. Not sure if we need to know this...
Sun Nov 08, 2020 9:57 am
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 7
Views: 19

### Re: Ionization Energy

For the first ionization energy you are removing an electron from a neutral atom, however, for the second ionization energy you are removing an electron from a cation. It is harder to remove an electron from a positively charged atom than a neutral atom because the positive charge holds on to the re...
Sun Nov 08, 2020 9:49 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: difference in p orbitals
Replies: 8
Views: 43

### Re: difference in p orbitals

To figure out how many electrons fill each orientation, you have to remember that due to electron repulsion, electrons in the same subshell (s,p,d,f) must occupy different orbitals with parallel spin before adding another electron to the same orbital (Hund's Rule). px, py and pz are the three orien...
Sun Nov 08, 2020 9:41 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: F orbitals?
Replies: 21
Views: 82

### Re: F orbitals?

In one of his lectures in week 4 he said we just need to know about the elements in the s, p, and d blocks (just the first row).
Sun Nov 08, 2020 9:38 am
Forum: Ionic & Covalent Bonds
Replies: 7
Views: 28

The neighboring atom is the same atom, So the atomic radius of Carbon would be half the distance between the center of two neighboring carbon atoms. If the neighboring atom was different it would be an ionic radius I believe.
Fri Nov 06, 2020 1:35 pm
Forum: Lewis Acids & Bases
Topic: Octet question
Replies: 7
Views: 60

### Re: Octet question

I think we just have to memorize the exceptions. For example, Boron doesn't usually have an octet but has 6 valence electrons. Both Boron and Aluminum are commonly involved in Lewis acids and base reactions.
Fri Nov 06, 2020 1:33 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ground-State Electron Configuration
Replies: 3
Views: 22

### Re: Ground-State Electron Configuration

I think either is fine but I usually do the noble-gas configuration because it is easier for me to recognize the valence electrons
Fri Nov 06, 2020 11:11 am
Forum: Lewis Structures
Topic: Lewis structures
Replies: 2
Views: 26

### Re: Lewis structures

When drawing Lewis structures that require multiple bonds (like a double), will the atom with less ionization energy form the double or triple bond?
Fri Nov 06, 2020 11:07 am
Forum: Student Social/Study Group
Topic: Test Scored for Midterm 1
Replies: 49
Views: 345

### Re: Test Scored for Midterm 1

The scores were released yesterday and can be viewed on ccle under grades
Fri Nov 06, 2020 11:05 am
Forum: Student Social/Study Group
Topic: Test Anxiety
Replies: 62
Views: 230

### Re: Test Anxiety

When I am about to take a very stressful test or give a presentation, I take a minute and raise my shoulders, kinda like a turtle. I let the tension build up for 30 seconds and then I take a deep breath and lower my shoulders. I feel like it gets rid of some of the stress. Its kinda weird but I saw ...
Fri Nov 06, 2020 11:00 am
Forum: Ionic & Covalent Bonds
Replies: 38
Views: 143

As you move towards the right of the periodic table the atomic number increases which gives the amount of protons in the nucleus, and a more positive nucleus has a greater pull on the electrons, thus decreasing the atomic radius.
Fri Nov 06, 2020 10:57 am
Forum: Octet Exceptions
Topic: Exceptions
Replies: 9
Views: 46

### Re: Exceptions

The books says there are several types of exceptions: - a molecule might have an odd number of electrons so octet formations is numerically impossible (radicals) - atoms of certain elements might be able to accommodate more than eight electrons in their valence shell (expanded valence shell) -an ato...
Sun Nov 01, 2020 7:08 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic Ions
Replies: 5
Views: 15

### Re: Isoelectronic Ions

I believe isoelectronic ions are ions with the same number of electrons. For example, Na[+] , Mg[+2], and F[-] would be isoelectronic ions because they all have 10 electrons.
Sun Nov 01, 2020 7:04 pm
Forum: DeBroglie Equation
Topic: Sapling HW #17
Replies: 6
Views: 35

### Re: Sapling HW #17

For the mass, find the molar mass of diatomic fluorine and convert that to kilograms (1kg=1000g) and then divide by avogadro's number to get Kg/mol
Fri Oct 30, 2020 12:37 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Sapling Learning Week 2,3, and 4 Homework Question 26
Replies: 3
Views: 42

### Re: Sapling Learning Week 2,3, and 4 Homework Question 26

Convert Angstroms to meters and then plug into Heisenberg's indeterminacy equation.
Fri Oct 30, 2020 12:35 pm
Forum: Lewis Structures
Topic: Line in place of paired dots
Replies: 8
Views: 43

### Re: Line in place of paired dots

I think he wants us to use lines to show a bond and for us to draw out lone pairs of electrons
Fri Oct 30, 2020 12:34 pm
Forum: Student Social/Study Group
Topic: Test Scored for Midterm 1
Replies: 49
Views: 345

### Re: Test Scored for Midterm 1

He said that he was doing some partial credit so that may take longer to figure out.
Fri Oct 30, 2020 9:02 am
Forum: Student Social/Study Group
Topic: Test Scored for Midterm 1
Replies: 49
Views: 345

### Re: Test Scored for Midterm 1

He said that he was doing some partial credit so that may take longer to figure out.
Tue Oct 27, 2020 8:09 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Question 1.B.27
Replies: 3
Views: 37

### Re: Question 1.B.27

Trevor was correct! The uncertainty in velocity is 10m/s because of the +- 5.0 and there is also a correction in the answer for this problem so I would check your answer on the chem website under the link titled solution manual errors, https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem1...
Tue Oct 27, 2020 11:46 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Question 1.B.27
Replies: 3
Views: 37

### Question 1.B.27

What would be ΔV for this problem?

1B.27 A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at 5.00 ± 5.0 m ⋅ s − 1 . What is the minimum uncertainty in its position?

Thanks!
Tue Oct 27, 2020 11:39 am
Forum: Photoelectric Effect
Topic: Need help with Experiment Conclusions
Replies: 3
Views: 40

### Re: Need help with Experiment Conclusions

I believe these are the only experiments we need to know for the midterm, and I think they observed diffraction patterns when shooting electrons through a crystal.
Tue Oct 27, 2020 11:36 am
Forum: DeBroglie Equation
Topic: Debroglie vs E=hc/wavelength
Replies: 2
Views: 16

### Re: Debroglie vs E=hc/wavelength

I also got confused between the two formulas but I think we just use E=hv when the question is asking about photons/electromagnetic radiation and then use the De Broglie Equation for particles with momentum.
Mon Oct 26, 2020 8:45 am
Forum: Einstein Equation
Topic: m vs nm
Replies: 66
Views: 361

### Re: m vs nm

I think always go with meters and then if they ask for it in nanometers, convert to nanometers if you have to but AFTER YOU HAVE CALCULATED THE ANSWER IN METERS because meters is the SI unit for length and is used for the speed of light constant.
Mon Oct 26, 2020 8:40 am
Forum: Properties of Light
Topic: Atomic Spectra Module Question
Replies: 5
Views: 52

### Re: Atomic Spectra Module Question

Scot Widjaja Dis 1J wrote:I'm confused because when I was watching the Atomic Spectra Lectures, the professor never talked about this topic. Would this be something required to know for the midterm and final?

I believe we need to know how to solve a question like this
Fri Oct 23, 2020 11:20 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook Problem E.25
Replies: 3
Views: 35

### Re: Textbook Problem E.25

Hi! A KNO3 molecule would be the formula unit in this problem. I googled the definition to make sure I was correct and I actually found an old post from Dr. Lavelle from 2018 in which he states: "formula units mean units of that formula. For example, suppose one has a small NaCl salt crystal is...
Wed Oct 21, 2020 11:25 am
Forum: Limiting Reactant Calculations
Topic: Theoretical Yield
Replies: 12
Views: 74

### Re: Theoretical Yield

It is in grams because we then use that theoretical yield and the actual yield, which is measured in grams, to get the percent yield.
Mon Oct 19, 2020 12:41 pm
Forum: DeBroglie Equation
Topic: standing circular wave model
Replies: 7
Views: 80

### Re: standing circular wave model

Is the standing circular wave model that shows waves out of phase (picture in lecture slides) inaccurate?
Mon Oct 19, 2020 12:38 pm
Forum: DeBroglie Equation
Topic: Wavelike and particle like behavior
Replies: 3
Views: 37

### Re: Wavelike and particle like behavior

Hi! Like you said "wavelike behavior is only detectable if the number is greater than 10^-15(m)". I believe particle like behavior is not always detectable because electrons passing through crystals show a diffraction pattern which means that they are exhibiting wavelike properties in that...
Mon Oct 19, 2020 12:32 pm
Forum: DeBroglie Equation
Topic: E=pc and E=pv
Replies: 10
Views: 80

### Re: E=pc and E=pv

The velocity (v) of a photon is c, so that is why he replaced the v to a c. I think he wanted us to realize where the equation e=mc^2 comes from.
Mon Oct 19, 2020 12:31 pm
Forum: DeBroglie Equation
Topic: No Rest Mass of a Photon
Replies: 4
Views: 49

### Re: No Rest Mass of a Photon

I was also confused by this statement but, like the others stated, I believe p=mv does not apply to photons
Mon Oct 19, 2020 12:28 pm
Forum: DeBroglie Equation
Topic: De Broglie Units
Replies: 4
Views: 39

### Re: De Broglie Units

Yes the mass should be in Kilograms because that is the SI unit that is used for mass and joules are = (Kg.m^2.s^-2)
Mon Oct 19, 2020 12:23 pm
Forum: Properties of Light
Topic: calculating photons
Replies: 4
Views: 24

### Re: calculating photons

If given the wavelength, plug that into the equation c=λv to get v, then plug that number into the equation E=hv to get the energy per photon. Once you have the energy of the photon, you just have to divide the total energy by the energy per photon to calculate the number of photons.
Mon Oct 19, 2020 12:15 pm
Forum: DeBroglie Equation
Topic: Wavelike properties of an Object
Replies: 5
Views: 37

### Re: Wavelike properties of an Object

A particle with a wavelength less than 10^{-15} m does not have detectable wavelike properties
Sun Oct 18, 2020 9:08 am
Forum: Properties of Light
Topic: Atomic Spectra Module Question
Replies: 5
Views: 52

### Re: Atomic Spectra Module Question

Thanks!
Sat Oct 17, 2020 10:04 am
Forum: Properties of Light
Topic: Atomic Spectra Module Question
Replies: 5
Views: 52

### Atomic Spectra Module Question

Hi! Can somebody explain how they got the answer for the first part of the question below. I used the formula c=λV but my answer did not match any of those listed. Thanks! 28. The meter was defined in 1963 as 1,650,763.73 wavelengths of radiation emitted by krypton-86 (it has since been redefined). ...
Fri Oct 16, 2020 9:46 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Q#39 Atomic Spectra Post Assessment
Replies: 4
Views: 30

### Re: Q#39 Atomic Spectra Post Assessment

I was also confused because I wasn't sure if I should plug 4 or 2 into n1.
Fri Oct 16, 2020 9:40 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 1A.15
Replies: 3
Views: 30

### Re: 1A.15

Just remember that the Balmer series consists of lines within the visible region and that n1=2 (and n2=3,4,...). While the Lyman series consists of lines within the Ultraviolet region of the spectrum and that n1=1 (and n2=2,3,...)

Hope this helps!
Tue Oct 13, 2020 11:13 am
Forum: SI Units, Unit Conversions
Topic: Nomenclature
Replies: 7
Views: 68

### Re: Nomenclature

I believe we just need to know the basic molecules and for the more complicated molecules he will give us the formula. That being said, some of the extra practice questions in the textbook did not give the formulas.
Mon Oct 12, 2020 10:58 am
Forum: Properties of Light
Topic: Light Intensity
Replies: 7
Views: 53

### Re: Light Intensity

Hi! Increasing the light intensity means increasing the amplitude of the waves. This does not increase the amount of electrons emitted while increasing the number of photons would increase the number of electrons emitted. That is why Dr. Lavelle told us to think about it as photons and not waves. Ho...
Mon Oct 12, 2020 10:53 am
Forum: Significant Figures
Topic: Rounding off answers in textbook [ENDORSED]
Replies: 4
Views: 50

### Re: Rounding off answers in textbook[ENDORSED]

Hi! You should wait to round your answer until you have done all the calculations and then make sure to round to the correct number of sig figs. It helps to keep track of the digits while doing the calculation so you know how many sig figs you need in the final answer.
Mon Oct 12, 2020 10:46 am
Forum: Properties of Light
Topic: Quanta and Photons
Replies: 19
Views: 162

### Re: Quanta and Photons

Hi! I believe based on the example, the transferable unit is the amount of water being poured from the bucket and if we were to increase the sensitivity of the experiment we would find that the smallest transferable unit it one H20 molecule. I think he is just trying to show the difference between c...
Mon Oct 12, 2020 10:38 am
Forum: Properties of Light
Topic: Light Intensity and Frequency
Replies: 7
Views: 81

### Re: Light Intensity and Frequency

Hi! Light intensity does not increase the energy of light, if it did then increasing the intensity would have ejected more electrons but studies found that this was not true. Thus, it is better to think of light in terms of photons interacting with electrons and not light in terms of wave properties.
Sun Oct 11, 2020 1:15 pm
Forum: SI Units, Unit Conversions
Topic: Unit Rounding
Replies: 11
Views: 74

### Re: Unit Rounding

Hello! During the calculations you should not round but use exact numbers. Once you get your final answer you will round that to the correct number of significant figures. When rounding, if the last digit is above 5, round up, if the last digit is below 5, round down, and if the last digit is 5 roun...
Thu Oct 08, 2020 5:08 pm
Forum: Limiting Reactant Calculations
Topic: Significant figures when using scientific notion
Replies: 5
Views: 35

### Significant figures when using scientific notion

I was looking over the answers for the fundamental questions in part E and some of the answers that were in scientific notation form had 2 sig figs while others had 3 sig figs. Does it just depend on the problem?
Thu Oct 08, 2020 10:06 am
Forum: Molarity, Solutions, Dilutions
Topic: Sapling HW Question 6
Replies: 4
Views: 53

### Re: Sapling HW Question 6

Your calculation would have been more accurate if you did not round 0.04523 to .045. Since you rounded, you got 100 ml instead of 102.8 ml. It's better if you wait to round until the end.
Wed Oct 07, 2020 9:19 am
Forum: Empirical & Molecular Formulas
Topic: Sapling HW 9
Replies: 21
Views: 217

### Re: Sapling HW 9

Blake Ballew 1E to find the moles of each element that are already in the compound you just need to look at the subscripts. For example, in H20 you have 2 moles of hydrogen and in CO2 you have 1 mole of Carbon. Hope this helps!
Mon Oct 05, 2020 3:19 pm
Forum: Molarity, Solutions, Dilutions
Topic: Units for Dilution Equation [ENDORSED]
Replies: 23
Views: 182

### Re: Units for Dilution Equation[ENDORSED]

For the example in the lecture about Dilution, Dr. Lavelle converted mL to liters when doing his calculations but then converted his final answer back to mL. Perhaps it is dependent on the question and the quantity of the answer. It would make more sense if you told someone to measure 15 mL of a sol...
Mon Oct 05, 2020 9:06 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 226
Views: 116432

### Re: Advice from a Medical Student[ENDORSED]

Thank you so much for this information. What other classes/teachers do you think prepared you well for the MCAT and medical school?
Mon Oct 05, 2020 9:00 am
Forum: Significant Figures
Topic: Significant Figures In A Given Weight
Replies: 11
Views: 177

### Re: Significant Figures In A Given Weight

Hi! I believe you would only use one significant figure when giving your answer because when multiplying/dividing, the value with the least significant figures determines the number of significant figures in the answer and 1 sig fig is the least amount of sig figs you can have. The Everything you wa...