Intermolecuar forces--> forces between different molecules (ex: hydrogen bonding)
Intramolecular forces--> forces within the same one molecule (ex: ionic bonds)
Search found 44 matches
- Sun Dec 01, 2019 11:34 pm
- Forum: Ionic & Covalent Bonds
- Topic: Intra vs Inter molecular forces
- Replies: 7
- Views: 1451
- Sun Dec 01, 2019 11:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: strength of bonds
- Replies: 14
- Views: 1050
Re: strength of bonds
yes, strength does correlate to melting points. The stronger the bond, the more energy required to break it, thus the higher the temp/energy required
- Sun Dec 01, 2019 11:30 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test #2 handback
- Replies: 11
- Views: 730
Re: Test #2 handback
We will be getting them back in discussion. If you are worried about the time to review it before the final, I'm sure you can email your TA to meet with them during office hours to go over it sooner!
- Sun Dec 01, 2019 11:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 4378
Re: Bent vs linear
A bent molecule must have at least one lone pair on the central atom. A molecule will be linear without the lone pair because there is nothing pushing down on them. When you add the lone pair, the other two atoms want to be as far away (repulsion) causing the molecule to be bent
- Sun Dec 01, 2019 11:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Shape
- Replies: 31
- Views: 3033
Re: Bent Shape
If their is one lone pair on the central atom when connected to two adjoining atoms, you will have a bent structure. Without the lone pair, the angle would be 180 degrees, or completely linear. However, the one lone pair pushes down on the outside two atoms creating a bond of less than 180
- Mon Nov 25, 2019 12:17 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 4378
Re: Bent vs linear
The biggest difference between linear and bent is to notice whether something is pushing down on the outside two atoms (such as a lone pair on the central atom). Hope this helps :)
- Mon Nov 25, 2019 12:16 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR formula
- Replies: 5
- Views: 343
Re: VSEPR formula
From the VSEPR formula we can find approximations of bond angles by comparing to whether they will be greater or less than our ideal angles (90, 180, 109.5 etc.) The only way to find the exact values is by using the Schrodinger equation which has not been covered thus far! Hope this helps :)
- Mon Nov 25, 2019 12:06 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs on Cenrtral Atom
- Replies: 11
- Views: 667
Re: Lone Pairs on Cenrtral Atom
Lone pairs on the central atom cause repulsion! This results in the surrounding atoms to be pushed closer together in efforts of getting as far away from these lone pairs as possible. It is more stable for bonds to be closer together than to the lone pair since lone pairs have a higher repulsion. Fo...
- Mon Nov 25, 2019 12:04 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond angles
- Replies: 7
- Views: 461
Re: Bond angles
Another important concept to remember is that VSEPR cannot provide us the exact bond angle, just approximate if it will be greater or less than our key angles (90, 180, 109.5)
- Mon Nov 25, 2019 12:02 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Hydrogen Bonding
- Replies: 13
- Views: 735
Re: Hydrogen Bonding
Yes. This is because Hydrogen's partial positive charge is attracted to a partial negatively charged atom (Nitrogen, oxygen, or fluorine) to create a hydrogen bond. This is why the resulting molecule is polar! Hope this helps :)
- Fri Nov 15, 2019 12:59 am
- Forum: DeBroglie Equation
- Topic: When to Use
- Replies: 8
- Views: 521
Re: When to Use
You use de broglie to find the velocity or wavelength of something with a mass such as an electron, photon... This is why we cannot use de broglie when dealing with light because light does not have a mass.
- Fri Nov 15, 2019 12:54 am
- Forum: Lewis Structures
- Topic: Lewis Structure
- Replies: 6
- Views: 445
Re: Lewis Structure
To find the lowest energy Lewis structure, you will need to examine formal charge. Lewis Structures with the lowest energy will have formal charges that cancel out to be zero or match the charge of the molecule if provided.
- Fri Nov 15, 2019 12:51 am
- Forum: Octet Exceptions
- Topic: Reasoning for Octet Exception
- Replies: 19
- Views: 1254
Re: Reasoning for Octet Exception
Rows three and beyond can have an expanded octet (hold more than 8 electrons) because they have access to the s, p AND d orbitals. Having access the the d orbital allows ten electrons to be used in addition to the octet. Rows 2 and above cannot have an expanded octet because they only utilize s and ...
- Fri Nov 15, 2019 12:49 am
- Forum: Octet Exceptions
- Topic: expanded octet
- Replies: 7
- Views: 667
Re: expanded octet
The elements that are in row three and below can have expanded octets. This is due to the fact that the elements row three and below can utilize the d orbital, allowing an additional ten electrons after the initial octet. Row 2 and above however, is limited to an octet, eight electrons, because they...
- Mon Nov 11, 2019 12:47 am
- Forum: Properties of Light
- Topic: Hz vs. frequency
- Replies: 7
- Views: 655
Re: Hz vs. frequency
Hz is also known as s^-1 and is simply the unit for frequency. So, if they ask you to find the frequency, your answer should be in Hz.
- Mon Nov 11, 2019 12:45 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: L quantum number
- Replies: 5
- Views: 430
Re: L quantum number
The quantum number (l) can be any whole number, positive value from 0 to n-1. So if n=12, as it does in this case, l can equal any number from 0-11.
l= 0,1,2,3,4,5,6,7,8,9,10,11
l= 0,1,2,3,4,5,6,7,8,9,10,11
- Mon Nov 11, 2019 12:43 am
- Forum: DeBroglie Equation
- Topic: unit of wavelength
- Replies: 5
- Views: 551
Re: unit of wavelength
according to SI units, you measure wavelength in meters (m) since it is technically a distance! However, a lot of the wavelengths we find are much smaller than this so sometimes it is easier to keep track of using other units such as nm. (# x 10^-9 m)
- Mon Nov 11, 2019 12:41 am
- Forum: Lewis Structures
- Topic: Formal Charges
- Replies: 15
- Views: 1012
Re: Formal Charges
First, you want to avoid charges at all costs unless the molecule has a charge. If the molecule has a charge and you need to put charge somewhere, do not put it on the central atoms since this is the least electronegative. It also makes sense to have a charge on the outside atoms because these will ...
- Mon Nov 11, 2019 12:38 am
- Forum: Ionic & Covalent Bonds
- Topic: Bond Strength
- Replies: 8
- Views: 515
Re: Bond Strength
Another important thing to note from the midterm is bond strength and length between single, double, and triple bonds. These are the trends:
Bond Length: single bond > double bond > triple bond
Bond Strength: triple bond > double bond > single bond
Bond Length: single bond > double bond > triple bond
Bond Strength: triple bond > double bond > single bond
- Sun Nov 03, 2019 6:31 pm
- Forum: Photoelectric Effect
- Topic: Threshold Energy
- Replies: 5
- Views: 359
Re: Threshold Energy
threshold energy and work function are referring to the same concept. It is important to find whether the energy of the incoming photon matches or is greater than the work function because this determines whether or not an electron will be emitted from the metal surface.
- Sun Nov 03, 2019 6:09 pm
- Forum: DeBroglie Equation
- Topic: Confused about equations
- Replies: 7
- Views: 436
Re: Confused about equations
only use c= λv when there is light involved!!!!
Whenever there is a mass mentioned or involved in the problem DO NOT USE THE LIGHT EQUATIONS!!! Instead use λ=h/(mv)
Whether or not mass is involved will determine which equation you will use
Whenever there is a mass mentioned or involved in the problem DO NOT USE THE LIGHT EQUATIONS!!! Instead use λ=h/(mv)
Whether or not mass is involved will determine which equation you will use
- Sun Nov 03, 2019 6:06 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty in Speed [ENDORSED]
- Replies: 31
- Views: 17834
Re: Uncertainty in Speed [ENDORSED]
Another way to calc uncertainty in v:
10 ms^-1 +/- .5
You can take the +/- value and multiply it by 2. This is another way to find uncertainty in v
10 ms^-1 +/- .5
You can take the +/- value and multiply it by 2. This is another way to find uncertainty in v
- Sun Nov 03, 2019 6:04 pm
- Forum: Lewis Structures
- Topic: Steps to Drawing a Lewis Structure
- Replies: 6
- Views: 501
Re: Steps to Drawing a Lewis Structure
When drawing Lewis Structures, I begin by totaling the number of valence electrons (remember to include extra or remove according to ion charges: cations and anions). Next, draw a beginning structure with the least electronegative atom in the middle, single bonds to each element, and fill the octet ...
- Sun Nov 03, 2019 6:01 pm
- Forum: Lewis Structures
- Topic: Lewis Structures
- Replies: 9
- Views: 539
Re: Lewis Structures
In one of the review sessions, they mentioned that you should always aim to draw the Lewis Structure with the lowest energy. You only need to draw the resonance structures if the questions asks for them.
- Mon Oct 28, 2019 12:11 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Best Way To Study?
- Replies: 56
- Views: 3660
Re: Best Way To Study?
I think that doing the modules before lecture, going to lecture, doing ALL homework problems, going to discussion, and then going to workshop for any remaining questions if a really good way to study. Also there are great youtube and khan academy videos on more challenging topics! Best of luck :)
- Mon Oct 28, 2019 12:07 pm
- Forum: Photoelectric Effect
- Topic: One photon one atom interaction
- Replies: 14
- Views: 614
Re: One photon one atom interaction
Each photon must have enough energy (at least the same energy as the work function) for an electron to be emitted. This energy relates to the wavelength. So, the shorter the wavelength, the higher the energy. Once threshold energy is reached in each short wavelength photon, increasing the frequency ...
- Mon Oct 28, 2019 12:05 pm
- Forum: Photoelectric Effect
- Topic: kinetic energy
- Replies: 6
- Views: 337
Re: kinetic energy
The kinetic formula will be provided on the equation sheet. However, just know that we can use the kinetic equation to find the velocity of the electron. Hope this helps :)
- Mon Oct 28, 2019 12:04 pm
- Forum: Photoelectric Effect
- Topic: Increasing Light Intensity Photoelectric Effect
- Replies: 7
- Views: 913
Re: Increasing Light Intensity Photoelectric Effect
Because light acts as both a wave and a particle, increasing intensity alone will not effect the number of e- that are emitted unless each photon has enough energy (threshold energy) to emit an electron. You increase the energy of each individual photon by decreasing wavelength. Once the photons pas...
- Mon Oct 28, 2019 12:04 pm
- Forum: Photoelectric Effect
- Topic: Increasing Light Intensity Photoelectric Effect
- Replies: 7
- Views: 913
Re: Increasing Light Intensity Photoelectric Effect
Because light acts as both a wave and a particle, increasing intensity alone will not effect the number of e- that are emitted unless each photon has enough energy (threshold energy) to emit an electron. You increase the energy of each individual photon by decreasing wavelength. Once the photons pas...
- Sun Oct 20, 2019 11:30 pm
- Forum: Properties of Light
- Topic: Next test
- Replies: 23
- Views: 1117
Re: Next test
We will be given an equation sheet. However, some of the equations we have been using can be derived from equations provided on the sheet so watch out for those!
- Sun Oct 20, 2019 11:29 pm
- Forum: Properties of Light
- Topic: Midterm Exam
- Replies: 21
- Views: 730
Re: Midterm Exam
For Fall 2019, the midterm is November 6 from 6-8 and should cover week one through week five. I'm sure there will be review sessions to clear up any trouble areas!
- Sun Oct 20, 2019 11:26 pm
- Forum: Properties of Light
- Topic: speed of light and velocity
- Replies: 6
- Views: 266
Re: speed of light and velocity
It is important to remember that speed of light is a constant and velocity is not a constant!
c=3.00x10^8 m/s
Equally important to remember, that speed of light equals wavelength times frequency
c= (lamda)v= 3.00x10^8 m/s
c=3.00x10^8 m/s
Equally important to remember, that speed of light equals wavelength times frequency
c= (lamda)v= 3.00x10^8 m/s
- Sun Oct 20, 2019 11:22 pm
- Forum: Properties of Light
- Topic: Unit for Wavelength
- Replies: 34
- Views: 2538
Re: Unit for Wavelength
Wavelength measures the peak to peak distance, and therefore is measured in meters. It is also important to note that wavelength is not limited to peak to peak specifically, it can also refer to trough to trough.
Also remember that wavelength and frequency have an inverse relationship!
Also remember that wavelength and frequency have an inverse relationship!
- Sun Oct 20, 2019 11:19 pm
- Forum: Properties of Light
- Topic: What are the units of hertz
- Replies: 41
- Views: 2210
Re: What are the units of hertz
1 Hertz (Hz) = 1 cycle per second (s^-1) Frequency (v) is measured in Hertz example: an electric field that oscillates at 6.4x10^14 Hz (blue light) completes 6.4x10^14 cycles per second an electric field that oscillates at 4.3x10^14 Hz (red light) completes 4.3x10^14 cycles per second red light has ...
- Sun Oct 13, 2019 11:21 pm
- Forum: Empirical & Molecular Formulas
- Topic: empirical = molecular?
- Replies: 15
- Views: 979
Re: empirical = molecular?
The empirical formula shows the relative number of atoms that a molecule has The molecule formula shows the actual number of atoms If the molar mass of the molecular formula = the molar mass of the empirical formula, this simply means that the actual number of atoms is the relative/lowest possible n...
- Sun Oct 13, 2019 11:07 pm
- Forum: Empirical & Molecular Formulas
- Topic: Converting from grams to percentage
- Replies: 11
- Views: 7690
Re: Converting from grams to percentage
Empirical formulas show the ratio of each element in relation to the other elements. To find this, you need to compare their molar amounts. To find molar amounts, you need the grams. If the mass in grams is not provided, we can use the percentages and assume that the mass is 100 g. I find that when ...
- Sun Oct 13, 2019 11:03 pm
- Forum: Empirical & Molecular Formulas
- Topic: post test problem
- Replies: 3
- Views: 468
Re: post test problem
You are correct. For these types of problems, conservation of mass is essential!. The mass of Cobalt needs to be the same between reactants and products. You can then find mass Flourine by having total mass - cobalt mass (339.20 g - 996.08). This will give you the mass (in grams) of cobalt! Hope thi...
- Sun Oct 13, 2019 10:55 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Tutoring? [ENDORSED]
- Replies: 121
- Views: 289530
Re: Tutoring? [ENDORSED]
I have been attending the step it up, workshop, and office hour style review sessions and honestly I believe those are better review than a tutor. The instructors are very good and explain things in an easy to understand fashion. Plus, you get practice problems and tips that are directly from the cl...
- Sun Oct 13, 2019 10:51 pm
- Forum: Balancing Chemical Reactions
- Topic: Writing Out Reactions
- Replies: 6
- Views: 398
Re: Writing Out Reactions
I'm sure we will have to remember the polyatomic ions later on. It will be helpful to become familiar with the terminology and start looking for patterns which will better prepare you for later in this course. For now though, I believe they will specify which equations and molecules we should focus ...
- Fri Oct 04, 2019 12:11 pm
- Forum: Balancing Chemical Reactions
- Topic: adding a product
- Replies: 6
- Views: 198
Re: adding a product
According to the conservation of mass, no atom can be created nor destroyed in a reaction. This means that we cannot insert or remove any atom into a reaction as we please. What we can do however, is manipulate the whole numbers of moles (stoichiometric coefficients) to balance the equation out.
- Fri Oct 04, 2019 12:09 pm
- Forum: Balancing Chemical Reactions
- Topic: Understanding how to get whole #s [ENDORSED]
- Replies: 18
- Views: 1331
Re: Understanding how to get whole #s [ENDORSED]
2.44 is not close enough to round. If it was 2.98 I will usually round to 3 moles. When you divide by the smallest number and end up with a decimal answer, you will have to multiple every mole by whatever amount that will make that decimal a whole number. This is because we need whole moles as stoch...
- Fri Oct 04, 2019 12:06 pm
- Forum: Balancing Chemical Reactions
- Topic: When are atoms lost or created?
- Replies: 14
- Views: 1829
Re: When are atoms lost or created?
According to the conservation of mass, no atoms can be created nor destroyed in a closed reaction. This is in fact why we need to always balance equations before solving a problem. We need to ensure that the same number of moles of any atom are conserved between the reactant and product sides of the...
- Fri Oct 04, 2019 12:01 pm
- Forum: Balancing Chemical Reactions
- Topic: Fractions in front of compounds
- Replies: 12
- Views: 654
Re: Fractions in front of compounds
You want to multiply because we want whole moles in the stoichiometric coefficients.The only time you need to worry about multiplying is when the coefficients don't come out to be whole numbers when you divide by the lowest number. The only other time you need to worry about multiplication is if the...
- Fri Oct 04, 2019 11:57 am
- Forum: Balancing Chemical Reactions
- Topic: How to Balance A Chemical Reaction
- Replies: 7
- Views: 429
Re: How to Balance A Chemical Reaction
Also remember it's helpful to not start with oxygen! You start with the larger molecule because the single atoms (such as oxygen) are easier to balance out