Search found 29 matches

by Raymond Ko 1H
Thu Dec 06, 2018 12:41 am
Forum: Naming
Topic: Polyatomic ions and naming
Replies: 7
Views: 138

Re: Polyatomic ions and naming

Ashley P 4I wrote:Does anyone know the pages for the this in the 6th edition?


The list of polyatomic ions in the 6th edition is found in the back of the book on page A31.
by Raymond Ko 1H
Thu Dec 06, 2018 12:37 am
Forum: Identifying Acidic & Basic Salts
Topic: HF
Replies: 4
Views: 273

Re: HF

The size of atoms on a periodic table increases down a group. In the case of F, it is the smallest atom in the group, which consists of Cl, Br, I, etc. Because it is the smallest atom, when bonded to a hydrogen atom, the bond length is shortest, as the atomic radius is the shortest. Shorter bond len...
by Raymond Ko 1H
Thu Dec 06, 2018 12:32 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Net Dipole
Replies: 3
Views: 82

Re: Net Dipole

Yes, you are right about the lone pairs creating a dipole moment in the molecule. If there were no lone pairs (this would not be possible due to the number of electrons in the molecule), the dipoles would cancel each other out, and there would be no net dipole moment. However, the electron lone pair...
by Raymond Ko 1H
Thu Dec 06, 2018 12:30 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 4
Views: 79

Re: Molecular Shape

The lone pair on the Iodine atom pushes the other atoms down, creating a square pyramidal structure. The structure for an AX5 molecule is trigonal bipyramidal, so removing one of the bonds and replacing it with a lone pair would result in repulsion.
by Raymond Ko 1H
Sat Nov 24, 2018 8:22 pm
Forum: Bond Lengths & Energies
Topic: Single, Double, Triple Bond Lengths
Replies: 5
Views: 127

Re: Single, Double, Triple Bond Lengths

In addition, when looking at the molecule and bonding geometrically, pi bonds are formed between atoms that are closer in distance. Also, the shorter the bond, the stronger the bond, so you can think of it that way when determining which is the longest and shortest.
by Raymond Ko 1H
Sat Nov 24, 2018 8:16 pm
Forum: Hybridization
Topic: Sigma/Pi Bonds
Replies: 5
Views: 83

Re: Sigma/Pi Bonds

When you draw the lewis structure for a molecule, all of the single bonds are sigma bonds. When you see a double bond or triple bond, the bond consists of a single bond and a pi bond for every additional bond required for the molecule to form. For example, a C2H4 molecule has 5 sigma bonds and 1 pi ...
by Raymond Ko 1H
Sat Nov 24, 2018 8:14 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: Salts Dissolving
Replies: 1
Views: 65

Re: Salts Dissolving

Salts dissolve in water because the water molecule is polar and because salts are made of bonding between cations and anions. The negative portion of the water molecule is attracted to the cation of the salt, and the positive end of the water molecule is attracted to the anion of the salt. These att...
by Raymond Ko 1H
Fri Nov 16, 2018 11:18 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.25 (7th ed)
Replies: 2
Views: 64

Re: 2E.25 (7th ed)

The first instance with the Cl atoms arranged on opposite ends of the molecule would result in a nonpolar molecule as the Cl atoms, which are more electronegative, would have dipoles that cancel. However, when the Cl atoms are on the same side of the molecule, there is a net delta negative charge to...
by Raymond Ko 1H
Fri Nov 16, 2018 11:09 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Distance from Central Atom
Replies: 8
Views: 128

Re: Distance from Central Atom

If you imagine a methane molecule (CH4) molecule drawn on the white board with the shaded and hatched triangles showing the VSEPR shape, the shaded triangle shows a Hydrogen atom that is coming out from the white board toward you. The hatched triangle shows a Hydrogen atom protruding behind the whit...
by Raymond Ko 1H
Fri Nov 16, 2018 11:06 am
Forum: Dipole Moments
Topic: Polar vs. Nonpolar
Replies: 5
Views: 128

Re: Polar vs. Nonpolar

You can tell which atom in the molecule has the delta negative or delta positive charge by determining which atom is more electronegative. Based on the periodic trends we learned for electronegativity, you can determine which molecules would attract a bonding pair of electrons more. The more electro...
by Raymond Ko 1H
Thu Nov 08, 2018 11:02 am
Forum: Bond Lengths & Energies
Topic: Bond Length and Bond Strength
Replies: 5
Views: 131

Re: Bond Length and Bond Strength

Bond length and strength can also be tied to different kinds of bonds as well such as ionic bonds compared to covalent bonds, dipole moments, Van der Waals forces, and hydrogen bonds. An increasing bond length yields a weaker bond.
by Raymond Ko 1H
Thu Nov 08, 2018 10:59 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge & Stable lewis structures
Replies: 6
Views: 168

Re: Formal Charge & Stable lewis structures

The goal is to have the sum of all the formal charges of the atoms in the molecule add up to the actual charge of the molecule. When determining the formal charges for each individual atom, I think it is most ideal for each atom to have a minimum charge. For example, it would be a more stable Lewis ...
by Raymond Ko 1H
Thu Nov 08, 2018 10:55 am
Forum: Lewis Structures
Topic: Formal charges
Replies: 15
Views: 243

Re: Formal charges

Unless specifically instructed to do so, I don't think you need to write the formal charge for each Lewis structure you write. When you are trying to determine which Lewis structure for the particular molecule is most stable and ideal, it may be useful to write the formal charges in order to compare...
by Raymond Ko 1H
Fri Nov 02, 2018 11:13 am
Forum: Trends in The Periodic Table
Topic: Periodic trends
Replies: 4
Views: 91

Re: Periodic trends

We should generally know 4 trends, I believe: Ionization energy increases across a period and decreases down a group. Electron Affinity increases across a period and decreases down a group. Atomic Radius decreases across a period and increases down a group. Electronegativity increases across a perio...
by Raymond Ko 1H
Fri Nov 02, 2018 11:09 am
Forum: Electronegativity
Topic: Electronegativity calculation
Replies: 4
Views: 103

Re: Electronegativity calculation

Dr. Lavelle said we will be given the values for electronegativity when we calculate differences. However, he did state in lecture that electronegativity is generally calculated by adding the ionization energy and electron affinity and dividing that sum by some constant. Don't worry about calculatin...
by Raymond Ko 1H
Fri Nov 02, 2018 11:08 am
Forum: Lewis Structures
Topic: Lewis Acid and Bases
Replies: 2
Views: 59

Re: Lewis Acid and Bases

Lewis structures and Lewis acids and bases will be on the midterm. All the material that we covered in lecture, up to and including the lecture on Wednesday, October 31, will be on the midterm!
by Raymond Ko 1H
Fri Oct 26, 2018 11:20 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions to Trends
Replies: 3
Views: 101

Re: Exceptions to Trends

The exceptions to the trends of electron configuration arrange in different ways because the goal of atoms is to arrange their electrons in the most stable manner, with the lowest energy. Also remember that when you are turning atoms into anions and removing electrons, always take electrons from the...
by Raymond Ko 1H
Fri Oct 26, 2018 11:15 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Isoelectronic Molecules
Replies: 2
Views: 68

Re: Isoelectronic Molecules

Another example is Se2-, Br-, Kr, Rb+, and Sr2+ are all isoelectronic because they all have the same number of electrons, although they may have different atomic numbers.
by Raymond Ko 1H
Fri Oct 26, 2018 11:13 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Affinity [ENDORSED]
Replies: 7
Views: 195

Re: Electron Affinity [ENDORSED]

To summarize, electron affinity is the energy released when electrons are added to an atom in the gas phase. Elements in the top right of the period table, up till group 17, generally have high electron affinities. Adding electrons to filled valence shells is unfavorable because further energy is re...
by Raymond Ko 1H
Fri Oct 19, 2018 9:51 pm
Forum: DeBroglie Equation
Topic: wave property
Replies: 4
Views: 93

Re: wave property

Adriana_4H wrote:What do you mean by resting mass?


Resting mass means that when an object has no velocity (momentum), such as a vase sitting on a table or a book on a desk, the object has a mass that can be measured. Photons do not have measurable mass without momentum, meaning they have no resting mass.
by Raymond Ko 1H
Fri Oct 19, 2018 9:48 pm
Forum: DeBroglie Equation
Topic: DeBroglie wavelike properties question
Replies: 4
Views: 121

Re: DeBroglie wavelike properties question

The previous answer is completely correct. I just wanted to add that there was a sort of threshold, or limit, to the wavelengths that detectors can actually measure in real life, which I think was around 10^-10 m.
by Raymond Ko 1H
Fri Oct 19, 2018 9:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electrostatic Attraction
Replies: 5
Views: 86

Re: Electrostatic Attraction

Electrostatic attraction is essentially the attraction between the positively charged nucleus of an atom and the negatively charged electrons surrounding it. The greater the positive charge of the nucleus (the more protons), the greater the effective nuclear charge.
by Raymond Ko 1H
Fri Oct 12, 2018 3:42 pm
Forum: DeBroglie Equation
Topic: Negative Sign
Replies: 4
Views: 69

Negative Sign

For the equation involving atomic levels:
En = -(hR)/n^2
Could someone explain for me one more time why there is a negative sign at the beginning of the equation?
by Raymond Ko 1H
Fri Oct 12, 2018 3:31 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Wave Properties of electrons
Replies: 2
Views: 32

Re: Wave Properties of electrons

For diffraction patterns, the typical example would be having a barrier in the middle of a room with a tiny opening the size of an electron. If electrons behaved like particles, when electrons are sent toward the opening, they would pass through one by one, straight to the end of the room. However, ...
by Raymond Ko 1H
Fri Oct 12, 2018 3:26 pm
Forum: Properties of Light
Topic: Car Example in Class with De Brogile Equation
Replies: 8
Views: 112

Re: Car Example in Class with De Brogile Equation

I think your reasoning is correct, that detectors cannot read wavelengths less than 10^-18 meters long. If you put things into perspective, Professor also talked about how the length of bonds between atoms in a microscopic scale is measured in Angstroms, which are 10^-10. 10^-18 is an extremely smal...
by Raymond Ko 1H
Fri Oct 12, 2018 3:26 pm
Forum: Properties of Light
Topic: Car Example in Class with De Brogile Equation
Replies: 8
Views: 112

Re: Car Example in Class with De Brogile Equation

I think your reasoning is correct, that detectors cannot read wavelengths less than 10^-18 meters long. If you put things into perspective, Professor also talked about how the length of bonds between atoms in a microscopic scale is measured in Angstroms, which are 10^-10. 10^-18 is an extremely smal...
by Raymond Ko 1H
Mon Oct 01, 2018 11:52 am
Forum: SI Units, Unit Conversions
Topic: Formula Units: Molecules or Atoms
Replies: 5
Views: 115

Re: Formula Units: Molecules or Atoms

Kind of like what Timothy said, you'd want to see what "things" the problem is dealing with. For example, if the question was asking for the number of H2O, you'd want the answer in molecules because it would be incorrect to say a certain number of H2O "atoms". If the question was...
by Raymond Ko 1H
Mon Oct 01, 2018 11:47 am
Forum: Significant Figures
Topic: Significant Figures
Replies: 10
Views: 289

Re: Significant Figures

To avoid rounding errors at the end, try not to round numbers within the calculation, only at the end. A useful way to do this, especially when calculations contain lots of significant figures, is to store step-by-step calculations in your calculator and recall them in order to keep the true value. ...
by Raymond Ko 1H
Mon Oct 01, 2018 11:42 am
Forum: SI Units, Unit Conversions
Topic: Grams/mole
Replies: 12
Views: 345

Re: Grams/mole

Both notations essentially have the same meaning. Personally, I use the g/mol notation when I'm setting up stoichiometric calculations so that I can see the conversion factors clearly. However, when not performing those calculations such as when writing an answer or answering a question in paragraph...

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