Search found 29 matches

by Daniel Cho Section 1H
Thu Jun 07, 2018 11:04 am
Forum: Ionic & Covalent Bonds
Topic: Help on 3.53
Replies: 2
Views: 110

Re: Help on 3.53

What they mean by lower energy is that which lewis structure is more stable which in turns mean the lower the formal charge the more stable the lewis structure charge. A good mental shortcut for formal charge is to count the electrons around the atom and subtract the valence electrons from the numbe...
by Daniel Cho Section 1H
Thu Jun 07, 2018 11:01 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar VS Nonpolar shapes
Replies: 4
Views: 162

Re: Polar VS Nonpolar shapes

In addition, the polarity is focused on the electronegativity negativity. So compounds like F2 is nonpolar because their electronegativity difference is very small. It also depends on the molecular shape but you more so have to draw it out to see if any of the dipole moments cancel out. I hope this ...
by Daniel Cho Section 1H
Thu Jun 07, 2018 10:41 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Hybridization
Replies: 7
Views: 261

Re: Hybridization

You don't really have to memorize the shapes to figure out the hybridization. I think with practice, you can figure out its hybridization. For molecular shape, you have to memorize it based on the VSEPR formula. On the main topic, Hybridization is very simple to figure out. You look at the central a...
by Daniel Cho Section 1H
Fri Jun 01, 2018 4:58 pm
Forum: Hybridization
Topic: Sigma and Pi bonds and its relation to atomic orbitals.
Replies: 1
Views: 70

Sigma and Pi bonds and its relation to atomic orbitals.

I have a small question relating to the concept of sigma and pi bonds. I know that when there is a single bond, there is a sigma bond, and double bond having one sigma and one pi bond and so on with the triple bond. As I was thinking about the sigma and pi bond, is it correct to think that the sigma...
by Daniel Cho Section 1H
Fri Jun 01, 2018 4:46 pm
Forum: Lewis Structures
Topic: Central Atom(s)
Replies: 6
Views: 209

Re: Central Atom(s)

The central atom would be the atom that has the least amount of ionization energy because the atom is more likely to bond with an atom that takes little effort to remove the electron from the atom based on Lavelle's lecture. I hope this helps. Please correct me if my explanation is wrong in certain ...
by Daniel Cho Section 1H
Fri Jun 01, 2018 4:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.3 Structure and Shape [ENDORSED]
Replies: 4
Views: 119

Re: 4.3 Structure and Shape [ENDORSED]

It is generally better to draw the Lewis structures because not only do you see the bond angles and the amount of electrons bonded to the central atom. Also, it is a lot easier to see the regions of electron density around the central atoms to determine what shape compound it takes. I hope this help...
by Daniel Cho Section 1H
Wed May 23, 2018 5:24 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power
Replies: 2
Views: 339

Re: Polarizing Power

The main thing to understand about polarizing power and polarizability is that they are very dependent on the atomic or ionic radius or to put simply, dependent on size. For polarizing power, remember that it is always the smaller atom that would have the highest power because of its need to attract...
by Daniel Cho Section 1H
Tue May 22, 2018 1:55 pm
Forum: Lewis Structures
Topic: 3.41 part c
Replies: 4
Views: 144

Re: 3.41 part c

A good way to draw these Lewis structures is to split that compound into three different compounds where you would draw H2C first and then NH2 and COOH and then put these Lewis structures together. The carbon in H2C would then bond to the nitrogen in NH2 and then you bond the carbon from H2C to the ...
by Daniel Cho Section 1H
Tue May 22, 2018 1:42 pm
Forum: Octet Exceptions
Topic: Octet exceptions and Formal charges.
Replies: 6
Views: 365

Re: Octet exceptions and Formal charges.

When it comes to Lewis Structures, it becomes very paramount to calculating the formal charges because the main requirements to get a finalized lewis structure is that the elements are fully satisfied with their octet rules excluding the central atom that is period 3 and below as well as the other e...
by Daniel Cho Section 1H
Tue May 22, 2018 1:32 pm
Forum: Octet Exceptions
Topic: Octet Exception
Replies: 7
Views: 357

Re: Octet Exception

The main thing to understanding expanded octet is that it only works for elements in the 3p orbitals and below mainly because of the d orbitals which is not filled which acts another placeholder for the electrons to fill in the d orbital. I hope this helps as a way to understanding the expanded octe...
by Daniel Cho Section 1H
Fri May 18, 2018 10:37 am
Forum: Lewis Structures
Topic: Question 3.25
Replies: 2
Views: 91

Re: Question 3.25

A good way to create chemical formula is to think of the charges crossing over like cross multiplication. So for Magnesium Arsenide, Mg is 2+ based on the periodic table and As is 3-. Mg is your cation and As is your anion. When you put them together, your first impression would be Mg2+As3-. When yo...
by Daniel Cho Section 1H
Fri May 18, 2018 10:27 am
Forum: Lewis Structures
Topic: Identifying radicals [ENDORSED]
Replies: 4
Views: 183

Re: Identifying radicals [ENDORSED]

As an added bonus, when trying to draw the Lewis structure. When you see the odd number of valence electrons, my TA told me that when drawing the electrons, always start on the most electronegative atom since they are the atoms that want the electrons the most. Make sure to fill the atom until they ...
by Daniel Cho Section 1H
Fri May 18, 2018 10:21 am
Forum: Resonance Structures
Topic: How do Resonance Structures Work?
Replies: 4
Views: 201

Re: How do Resonance Structures Work?

A usual trend in Resonance particularly with compounds has a neutral is that there are two elements that has opposing formal charges such as +1 and -1. If you see that with a compound with a double bond that is a good indicator that the compound can be represented in resonance. I hope this helps. Pl...
by Daniel Cho Section 1H
Thu May 10, 2018 12:57 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Delta X
Replies: 4
Views: 248

Re: Delta X

You plug in the diameter for delta x because it gives you a range of where the particle could be without telling you the exact position of the object you are looking for. Think of this concept as a different version of the velocity's uncertainty with their plus, minus value. The plus-minus is exactl...
by Daniel Cho Section 1H
Thu May 10, 2018 12:53 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Mechanics Worksheet #9 [ENDORSED]
Replies: 4
Views: 416

Re: Quantum Mechanics Worksheet #9 [ENDORSED]

The general rule for these quantum numbers is that ml is in range for these choices but when you see n and l being the same number, just know that it is not possible. It is exactly like saying that there is a 3f orbital in the periodic table even though that orbital does not exist. Always know that ...
by Daniel Cho Section 1H
Thu May 10, 2018 12:47 pm
Forum: Ionic & Covalent Bonds
Topic: Memorization of Electronegativity
Replies: 6
Views: 313

Re: Memorization of Electronegativity

For now, you generally don't have to. I asked the exact same question back in high school chemistry and the general consensus is that we just need to understand the general trend of electronegativity and why the trend behaves in this pattern. In cases back in high school, my high school teacher gave...
by Daniel Cho Section 1H
Wed May 02, 2018 6:08 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Difference between orbitals
Replies: 4
Views: 114

Re: Difference between orbitals

A helpful tip and very important concept to know is that orbitals can be determined by l. As when l=0, it is the s orbital. And so on until it reaches l=3 being the f orbital. L 0 =s orbital 1= p orbital 2= d orbital 3= f orbital I hope this helps. Please correct me if I am wrong in certain places a...
by Daniel Cho Section 1H
Wed May 02, 2018 6:03 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.25 hw
Replies: 2
Views: 96

Re: 2.25 hw

Congratulations! ^_^ Saying 6 electrons in 4p is correct. Think of it like orbital notation if you took high school chemistry but usually in the p orbitals, 6 electrons are needed to be filled to the brim with the electron because p has 3 orbital spaces in which the orbital must be filled with 2 ele...
by Daniel Cho Section 1H
Wed May 02, 2018 5:54 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Example 1.7
Replies: 2
Views: 164

Re: Example 1.7

A better way to look at the indeterminacy of the velocity is to find the values of whatever speed you are given plus and minus a random number. For example, plus minus 1 is doubled because you are subtracting the range which would lead to 1 and -1 mm/s. When you subtract 1 and -1 you would get 2 whi...
by Daniel Cho Section 1H
Wed Apr 25, 2018 7:00 pm
Forum: Photoelectric Effect
Topic: What is work function? [ENDORSED]
Replies: 15
Views: 1605

Re: What is work function? [ENDORSED]

The book says work function which is also considered threshold energy. Think of it as the limit the incoming photon light has to exceed in order to release the energy as it hits the metal.

I hope this helps. Correct me in places where I might be wrong.
by Daniel Cho Section 1H
Wed Apr 25, 2018 6:52 pm
Forum: Properties of Light
Topic: Wavelength/frequency
Replies: 11
Views: 403

Re: Wavelength/frequency

It is good to think of it with the equation E=(Planck's constant)(frequency) and speed of light=(wavelength)(frequency). An important skill is linking these two equations together. Let's try solving for frequency with the equation speed of light=(wavelength)(frequency) which the equation would end u...
by Daniel Cho Section 1H
Wed Apr 25, 2018 6:28 pm
Forum: Properties of Light
Topic: test 2
Replies: 18
Views: 593

Re: test 2

When memorizing the general order of wavelengths of the rays from gamma ray to radio waves, do we need to know the general trend of the wavelengths within the visible light as well as the numerical range for the waves?
by Daniel Cho Section 1H
Tue Apr 17, 2018 7:48 pm
Forum: Einstein Equation
Topic: When to use E=hc/wavelength
Replies: 6
Views: 344

Re: When to use E=hc/wavelength

I am very sure we would be given a formula sheet in front of the exam. A good way to check which formulas are on the formula sheet go to the class website and click constants which is one below everything you want to know about sig figs. Even though the formulas are given, it is very advisable to re...
by Daniel Cho Section 1H
Tue Apr 17, 2018 7:29 pm
Forum: Photoelectric Effect
Topic: Example 1.5 [ENDORSED]
Replies: 8
Views: 278

Re: Example 1.5 [ENDORSED]

Most likely, the mass of the electron will never change because it is a discovered fact of the mass until someone eventually debunks or improves the value. For now, we would be using this value as our mass of the electron. The mass would never vary. I hope this helps. Please correct me in places whe...
by Daniel Cho Section 1H
Tue Apr 17, 2018 7:23 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: HW 1.15
Replies: 6
Views: 247

Re: HW 1.15

For this problem, you kind of have to use to this equation as well as assume that n1= 1 because this is an example of the Lyman series as you look at the wavelength 102.6 nm in terms of the graph on page 7 letter b. Since you know your frequency would be 2.9329X10^15 Hz, you would set up this equati...
by Daniel Cho Section 1H
Tue Apr 10, 2018 11:57 am
Forum: Molarity, Solutions, Dilutions
Topic: Molarity conversions [ENDORSED]
Replies: 3
Views: 204

Re: Molarity conversions [ENDORSED]

As a side note, if you are given grams. You can just divide grams by the element's molar mass to find moles if you are trying to find Molarity or Volume.
by Daniel Cho Section 1H
Tue Apr 10, 2018 11:46 am
Forum: Empirical & Molecular Formulas
Topic: f11
Replies: 3
Views: 173

Re: f11

Just think of converting percent to mass like the formula for mass percentage. (Molar Mass of a specific element/ mass of entire compound) x 100% which explains why when you were given 50% C you convert that to 50g since you multiply by 100%. I hope this helps. Correct me if I am wrong in my explana...
by Daniel Cho Section 1H
Sun Apr 08, 2018 4:57 pm
Forum: Administrative Questions and Class Announcements
Topic: Modules
Replies: 5
Views: 215

Re: Modules

The modules are just study tools that reinforces your understanding of the topic on concepts you find confusing. I recommend using it to study; it is very helpful.
by Daniel Cho Section 1H
Sun Apr 08, 2018 4:52 pm
Forum: Administrative Questions and Class Announcements
Topic: Test #1 [ENDORSED]
Replies: 4
Views: 205

Re: Test #1 [ENDORSED]

For Test #1, are scientific calculators allowed for the test knowing that we will be working with scientific notations and the scientific calculators don't store text and equations?

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