Search found 35 matches

by Thomas Gimeno
Sun Nov 22, 2020 11:39 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: Instantaneous Dipoles
Replies: 4
Views: 11

Re: Instantaneous Dipoles

If its rod shaped then either end of the rod is likely partially charged and another charged rod can line up antiparallel making the dipole moment at either end of each particle very close to the dipole moments on the other particle. This means that both dipole moments on both molicules are interact...
by Thomas Gimeno
Sun Nov 22, 2020 11:30 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: Hydrogen Bond
Replies: 5
Views: 31

Re: Hydrogen Bond

Hydrogen bonds would occur because there is a hydrogen bonded to an oxygen. It doesn't matter what other atoms the oxygen would bind to because of how large the electronegativity difference is between hydrogen and oxygen. This means that the hydrogen would be partially positive and the oxygen would ...
by Thomas Gimeno
Sun Nov 22, 2020 11:21 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: London Dispersion
Replies: 24
Views: 54

Re: London Dispersion

While london dispersion forces always occur in groups of molecules, each individual molecule is not always participating in LDFs. Also LDFs can occur in one part of a molecule and not another part, all that is necessary is a sight where a difference in electron density can create a partial positive ...
by Thomas Gimeno
Sun Nov 22, 2020 11:16 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: Polarizablity
Replies: 10
Views: 18

Re: Polarizablity

Polarizability is how easily an electron can be pulled away from the cat ion and towards the anion. If the cation has a high polarizability then the molecule likely has high ionic character and low covalent character.
by Thomas Gimeno
Sun Nov 22, 2020 11:12 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: Dipole-Induced-Dipole and Dipole-Dipole
Replies: 4
Views: 13

Re: Dipole-Induced-Dipole and Dipole-Dipole

If it is dipole-dipole then the two molecules are polar and have a dipole at all times. If it is induced dipole that means that the molecule/s is/are non polar and only have a temporary dipole due to the random movement of electrons to one side of the molecule.
by Thomas Gimeno
Sun Nov 15, 2020 9:51 pm
Forum: Dipole Moments
Topic: Dipoles vs Ions
Replies: 5
Views: 28

Re: Dipoles vs Ions

Well so ionic and covalent bonds are the opposite ends of the spectrum of electronegativity difference with ionic having a high difference and covalent having a small difference. A dipole moment occurs when a bond has a significant difference in electronegativity but the difference is not high enoug...
by Thomas Gimeno
Sun Nov 15, 2020 9:47 pm
Forum: Electronegativity
Topic: polar vs nonpolar
Replies: 13
Views: 40

Re: polar vs nonpolar

In class he said that if the difference is greater than 2 it is considered ionic and if the difference is less than 1.5 it is considered covalent.
by Thomas Gimeno
Sun Nov 15, 2020 9:45 pm
Forum: Coordinate Covalent Bonds
Topic: formation of coordinate covalent bonds
Replies: 4
Views: 41

Re: formation of coordinate covalent bonds

Hydrogen usually exists in its H+ state and therefore generally will except electrons.
by Thomas Gimeno
Sun Nov 15, 2020 9:41 pm
Forum: Coordinate Covalent Bonds
Topic: General Question on Coordinate Covalent Bonds
Replies: 7
Views: 45

Re: General Question on Coordinate Covalent Bonds

I think about it like this, I draw each atom and the number of valance electrons it "should" have (so for nitrogen there would be 5). Then I started pairing up the electrons from different atoms to form bonds. If I find that all the valance electrons have been used up and the only way to f...
by Thomas Gimeno
Sun Nov 15, 2020 9:36 pm
Forum: Coordinate Covalent Bonds
Topic: Hydrogen bonds
Replies: 9
Views: 37

Re: Hydrogen bonds

Carbon and hydrogen have very similar electronegativities so when they are bonded together it is non polar. This means that their is no partial charges and it is these partial charges that cause hydrogen bonding to occur.
by Thomas Gimeno
Sun Nov 15, 2020 8:54 pm
Forum: Coordinate Covalent Bonds
Topic: Covalent Bond Character
Replies: 7
Views: 28

Re: Covalent Bond Character

Generally we think of ionic bonds being strictly one atom giving an electron to another atom and covalent bonds as two atoms sharing two electrons equally. This is untrue because in reality the vast majority of bonds have electrons shared a little bit. The covalent character is a way of describing h...
by Thomas Gimeno
Sun Nov 15, 2020 8:42 pm
Forum: Lewis Structures
Topic: Expanded Octets
Replies: 7
Views: 21

Re: Expanded Octets

The octet rule is just a representation of the fact that atoms in energy levels 1 and 2 want to fill their outer most s and p orbitals. When you start moving into higher energy states there are more orbitals and this results in the possibility of more than 8 valance electrons.
by Thomas Gimeno
Sun Nov 15, 2020 8:39 pm
Forum: Lewis Structures
Topic: Nitrate Ion Lewis Structure
Replies: 6
Views: 26

Re: Nitrate Ion Lewis Structure

To preface, this is just the way I think about it. The nitrogen would normally have 5 valence electrons meaning it can form three bonds and then have a lone pair. In this case though, the central nitrogen is forming a fourth bond meaning that one of the electrons from the lone pair is being used in ...
by Thomas Gimeno
Sun Nov 15, 2020 8:34 pm
Forum: Lewis Structures
Topic: VSEPR
Replies: 4
Views: 21

Re: VSEPR

I don't think vesper will be on the exam because it was taught after Wednesday. I think vesper is really helpful though especially for determining polarity. For example, it might look that h2o had an equal distribution of electrons but with vesper we know that it actually has a bent structure. This ...
by Thomas Gimeno
Sun Nov 15, 2020 8:29 pm
Forum: Lewis Structures
Topic: Sapling Weeks 5/6 HW #18
Replies: 7
Views: 21

Re: Sapling Weeks 5/6 HW #18

The way i was taught in high school was that larger ions have more electrons which can contribute to london dispersion forces. The more electrons an atom has, the larger the temporary dipole can be because there will be a greater difference in electrons between the positive and negative end.
by Thomas Gimeno
Sun Nov 08, 2020 11:45 pm
Forum: Ionic & Covalent Bonds
Topic: Sapling #2
Replies: 6
Views: 38

Re: Sapling #2

You're missing a possible partial positive charge on the nitrogen atom. This occurs because normally nitrogen only makes three bonds but if it looses one electron (making it +1) it can form a fourth bond.
by Thomas Gimeno
Sun Nov 08, 2020 11:43 pm
Forum: Ionic & Covalent Bonds
Topic: HW Question
Replies: 4
Views: 21

Re: HW Question

London dispersion forces are always present and there would also be a dipole-dipole interaction due to the partial negative charge of the O in the OH group.
by Thomas Gimeno
Sun Nov 08, 2020 11:40 pm
Forum: Ionic & Covalent Bonds
Topic: Size of Bonds
Replies: 28
Views: 90

Re: Size of Bonds

Double bonds have a greater interaction between electrons than single bonds. If you think about it in the electron cloud model, more of the electron clouds would have to overlap in odder to form a double bond when compared to a single bond. This increased overlap can be seen as the nuclei getting cl...
by Thomas Gimeno
Sun Nov 08, 2020 11:38 pm
Forum: Ionic & Covalent Bonds
Topic: formal charge
Replies: 8
Views: 35

Re: formal charge

The formal charge is important because it shows where there are more or less electrons. For example, if an oxygen atom has three lone pairs of electrons and one bond, it would have a negative formal charge. This is because oxygen would normally only have two lone pairs of electrons along with two mo...
by Thomas Gimeno
Sun Nov 08, 2020 11:34 pm
Forum: Ionic & Covalent Bonds
Topic: Atomic Radii
Replies: 5
Views: 21

Re: Atomic Radii

The 1s state is on the first energy level and the 2p state is on the second, if you remember the diagram he showed, the second energy level is father away from the nucleus making the overall radius larger.
by Thomas Gimeno
Sun Oct 25, 2020 11:37 pm
Forum: Properties of Light
Topic: Balmer or Lyman Series
Replies: 9
Views: 45

Re: Balmer or Lyman Series

The primary difference is energy of the light produced. Lynman has a large jump from the 2nd or higher to the 1st energy level which means that high energy light is release which will in turn be ultraviolet and invisible to the naked eye. Balmer has a smaller jump from the 3rd or higher to the 2nd e...
by Thomas Gimeno
Sun Oct 25, 2020 11:32 pm
Forum: Properties of Light
Topic: Speed of light
Replies: 25
Views: 119

Re: Speed of light

I wouldn't worry too much because usually the answer accounts for a slight bit of variation based on constants but i think if the text book is using 2.998*10^8 then it's probably your best bet.
by Thomas Gimeno
Sun Oct 25, 2020 11:29 pm
Forum: Properties of Light
Topic: Equation clarifications
Replies: 4
Views: 28

Re: Equation clarifications

Well solving for the energy of a photon is plank's constant times frequency and you can sub in the speed of light over the wavelength for frequancy. The equation you wrote has speed of light over frequency (Or i may have misread it cause you can't use greek symbols). But also, a question could ask a...
by Thomas Gimeno
Sun Oct 25, 2020 11:20 pm
Forum: Properties of Light
Topic: How are you guys studying for the midterm?
Replies: 19
Views: 53

Re: How are you guys studying for the midterm?

I really like to just go through my notes and collect all the equations we learned. Then I write out an equation sheet where I identify each part of the equation, explain its significance and when it is used, and then try and do one example problem with it. I find it really helpful because it prepar...
by Thomas Gimeno
Sun Oct 25, 2020 11:15 pm
Forum: Properties of Light
Topic: Units for wavelength/frequency
Replies: 18
Views: 84

Re: Units for wavelength/frequency

Wave length will usually be given in nm which is m*10^-9 however there was a problem that gave wavelength in um which is only m*10^-6. Frequency is in Hz which is just 1/seconds. You can think of it a per second if that helps. It makes sense because when wave length and frequency are multiplied you ...
by Thomas Gimeno
Sun Oct 18, 2020 10:25 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's #
Replies: 31
Views: 291

Re: Avogadro's #

The main purpose of Avogadro's number is to covert between # of particles and mols. The number itself, 6.022x10^23, represents the # of particles in one mole. It super helpful when you either have or need the # of particles but it also comes up in some equations (usually for the purpose of convertin...
by Thomas Gimeno
Sun Oct 18, 2020 10:19 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Calculating number of moles of an element
Replies: 10
Views: 55

Re: Calculating number of moles of an element

It 100% for simplicity. When you have 45% of something, its a lot easier to just write it as 45g then as an obscure number representing a different total
by Thomas Gimeno
Sun Oct 18, 2020 10:15 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Exercise E.9
Replies: 6
Views: 103

Re: Exercise E.9

The key is the last part of the name: heptahydrate. When hydrate is at the end of the name of a chemical it means water molecules are incorporated into the structure of that chemical. In this case there are seven molecules of water because the prefix hepta means seven. When it comes to writing this,...
by Thomas Gimeno
Sun Oct 18, 2020 10:10 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook Problem E.15 [ENDORSED]
Replies: 3
Views: 71

Re: Textbook Problem E.15 [ENDORSED]

Well the first step is to identify what the sulfide would look like. Because Ca would give up its two valence electrons it has a charge of +2. Sulfur wants to gain two electrons to fill its outer shell which makes it -2. This means the Calcium Sulfide is just CaS. To then find the molar mass you can...
by Thomas Gimeno
Sun Oct 18, 2020 10:05 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E23 Confused
Replies: 4
Views: 63

Re: E23 Confused

Because there is one atom of Cu in CuBr2, for every mole of CuBr2 you have one mole of Cu. I think you might be looking at the Br2 and thinkcing that's why you divide by however the fact that there are 2 Br atoms does not change the ratio between Cu and CuBr2.
by Thomas Gimeno
Sun Oct 11, 2020 11:07 am
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 200
Views: 140743

Re: Rusty on High School Chem [ENDORSED]

I took AP Chem in my junior year and I am a first year now. I'm finding that a good amount of the content is coming back but whenever I'm unsure about a basic, I really like to go n youtube and find someone explaining the topic. A lot of teachers will post lectures and practice problems online which...
by Thomas Gimeno
Sun Oct 11, 2020 11:04 am
Forum: Molarity, Solutions, Dilutions
Topic: sapling hw #7
Replies: 17
Views: 133

Re: sapling hw #7

Well logically, if you add the mass of the CaCl2 and the water, you should get the mass of the total solution. And, CaCl2 represents 32.5% then the water must represent 67.5% because water+CaCl2=100%. So if you multiply the total mass by the .325 and .675 to find the masses of the CaCl2 and water re...
by Thomas Gimeno
Sun Oct 11, 2020 10:48 am
Forum: SI Units, Unit Conversions
Topic: SI Units
Replies: 13
Views: 101

Re: SI Units

I really like to write my units in my calculations for every problem. This allows me to make sure that all my units cancel and it's a nice little check to make sure I did the problem correctly because your units should match up with what the question is asking for.
by Thomas Gimeno
Sun Oct 11, 2020 10:43 am
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 173
Views: 34043

Re: Final Jitters

It helps to take practice tests. Either ones you find online or one you make yourself, they give you confidence and help you to know what to expect out of the test. Its a lot less scary to do something for the 5th time than to do it for the first time.
by Thomas Gimeno
Sun Oct 11, 2020 10:37 am
Forum: Student Social/Study Group
Topic: Chemistry News
Replies: 76
Views: 49749

Re: Chemistry News

For anyone who's interested in batteries, this article discusses the new development in charging lengths and long-term power storage. It's in the context of electric cars but the research could have really cool implications for clean energy. https://phys.org/news/2020-10-electrode-material-battery-c...

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