Search found 54 matches
- Sun Dec 05, 2021 1:37 pm
- Forum: Bronsted Acids & Bases
- Topic: Why is H-F a weak acid
- Replies: 19
- Views: 1292
Re: Why is H-F a weak acid
Bond length is the most important factor when determining the strength of acids. Since the H-F bond is shorter and stronger than the H-Cl bond (because Cl is a larger atom than F), it will be more difficult to remove the hydrogen atom from HF, making it a weaker acid than HCl.
- Sun Dec 05, 2021 1:32 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: How to Calculate OH- Concentration
- Replies: 18
- Views: 22117
Re: How to Calculate OH- Concentration
To find the OH- concentration given the H+ concentration, you can use the equation 1.0x10^-14/[H+].
- Sun Dec 05, 2021 1:29 pm
- Forum: Lewis Acids & Bases
- Topic: NH3 as a lewis base
- Replies: 23
- Views: 2094
Re: NH3 as a lewis base
Lewis bases are defined as atoms or molecules that can donate an electron lone pair. Since there is a lone pair on the nitrogen atom in NH3 that can be donated, it is a Lewis base.
- Sun Dec 05, 2021 1:27 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH to [H+]
- Replies: 40
- Views: 11706
Re: pH to [H+]
To get the pH from [H+], you take 10^-pH.
- Sun Dec 05, 2021 1:26 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Ka values
- Replies: 7
- Views: 334
Re: Ka values
Since pKa is the negative log of Ka, a smaller Ka would result in a larger pKa and a larger Ka would result in a smaller pKa.
- Sun Nov 28, 2021 12:19 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 12
- Views: 860
Re: Formal Charge
Formal charge doesn't really affect intermolecular forces, but it shows the stability in the structure of a molecule. A molecule with a structure with the least formal charges will be more stable than a molecule with a structure with more formal charges, and is therefore preferable.
- Sun Nov 28, 2021 12:12 pm
- Forum: Naming
- Topic: Aceive HW #2 Coordination Number
- Replies: 14
- Views: 581
Re: Aceive HW #2 Coordination Number
Yes, 6 would be the coordination number because the Co atom has 6 fluorines bonded to it. Only look at the atoms within the bracket when determining coordination number.
- Sun Nov 28, 2021 12:08 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Achieve Q5
- Replies: 7
- Views: 343
Re: Achieve Q5
The coordination number is 6 because the 3 NH3's and the 3 F's are all attached to the M, meaning the M has 6 ligands attached to it.
- Sun Nov 28, 2021 12:06 pm
- Forum: Naming
- Topic: Coordination Compounds
- Replies: 5
- Views: 291
Re: Coordination Compounds
I'm assuming that for the final, we'll only have the periodic table and list of formulas and constants that we had for previous midterms.
- Sun Nov 28, 2021 12:05 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Brackets and Coordination Number
- Replies: 13
- Views: 687
Re: Brackets and Coordination Number
Yes, when determining coordination number you only look at the atoms inside the brackets.
- Sun Nov 21, 2021 9:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Pi bonds
- Replies: 46
- Views: 1789
Re: Pi bonds
Any bond that is not a single bond will have a pi bond. The second and third bonds formed between atoms are pi bonds.
- Sun Nov 21, 2021 9:18 pm
- Forum: Bond Lengths & Energies
- Topic: Bond length in double vs single [ENDORSED]
- Replies: 57
- Views: 3732
Re: Bond length in double vs single [ENDORSED]
Since more electrons are shared in double bonds, double bonds have a stronger attraction and therefore the atoms are pulled closer together. Therefore, double bonds are shorter than single bonds.
- Sun Nov 21, 2021 9:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs Angular
- Replies: 61
- Views: 2663
Re: Bent vs Angular
Yes, they're the same! Bent and angular are just different names for the same shape.
- Sun Nov 21, 2021 9:12 pm
- Forum: Significant Figures
- Topic: Atomic Mass for Hydrogen
- Replies: 44
- Views: 3123
Re: Atomic Mass for Hydrogen
I would generally use 1.008 amu for the atomic mass of hydrogen because it is better to be more specific and accurate, but either one should work.
- Sun Nov 21, 2021 9:07 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polar bonds vs. Polar molecules
- Replies: 13
- Views: 815
Re: Polar bonds vs. Polar molecules
BeCl2 is a nonpolar molecule because it is symmetrical, and therefore the dipole moments are equal and opposite and cancel each other out.
- Sun Nov 14, 2021 9:35 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: polarizing power vs polarizability
- Replies: 11
- Views: 1241
Re: polarizing power vs polarizability
Polarizing power is the ability of a cation to distort an anion's electron. It is higher for smaller, more electronegative cations. Polarizability is how easily an anion's electron cloud is distorted. It is higher for larger, less electronegative anions.
- Sun Nov 14, 2021 9:30 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: Midterm 2 Question
- Replies: 22
- Views: 1387
Re: Midterm 2 Question
Stronger intermolecular forces between molecules will result in a higher melting/boiling point. For example, molecules with hydrogen bonding or dipole-dipole bonding will have a higher melting/boiling point than molecules with just London dispersion forces.
- Sun Nov 14, 2021 9:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Axial vs. Equatorial
- Replies: 23
- Views: 988
Re: Axial vs. Equatorial
Axial atoms lie on the vertical plane (y-axis) of the molecular structure. Equatorial atoms lie on the horizontal plane (x-axis) of the molecular structure.
- Sun Nov 14, 2021 9:22 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Electronegativity & Formal Charge
- Replies: 7
- Views: 458
Re: Electronegativity & Formal Charge
Ideally, atoms in a Lewis structure will all have a formal charge of 0. However, if there has to be a negative formal charge, it should be on the most electronegative atom. Lewis structures that have the fewest atoms with formal charges represent the most likely structure to occur.
- Sun Nov 14, 2021 9:18 pm
- Forum: Electronegativity
- Topic: Be vs Cl
- Replies: 49
- Views: 3306
Re: Be vs Cl
Chlorine is more electronegative because it is much further to the right than beryllium, whereas beryllium is only one row higher than chlorine.
- Sun Nov 07, 2021 10:58 pm
- Forum: Dipole Moments
- Topic: London dispersion and dipole dipole forces
- Replies: 5
- Views: 499
Re: London dispersion and dipole dipole forces
London dispersion forces are weak temporary forces resulting from two nearby atoms forming temporary dipoles. They occur between all molecules. Dipole-dipole interactions occur between the positively charged end of one polar molecule and the negatively charged end of another polar other molecule. Th...
- Sun Nov 07, 2021 10:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR [ENDORSED]
- Replies: 73
- Views: 6379
Re: VSEPR [ENDORSED]
VSEPR stands for valence-shell electron pair repulsion model. It explains the 3D shape of molecules due to the repulsion between electron-dense regions.
- Sun Nov 07, 2021 10:43 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: Achieve Question 18
- Replies: 9
- Views: 1748
Re: Achieve Question 18
London dispersion forces are the strongest in molecules with larger molar masses and larger surface areas.
- Sun Nov 07, 2021 10:38 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Calculating Formal Charge
- Replies: 8
- Views: 319
Re: Calculating Formal Charge
If you had to divide 2 by 0, that would mean that the atom shares no bonds with other atoms, meaning it is not part of a molecule. Therefore, this situation would not happen when calculating formal charge.
- Sun Nov 07, 2021 10:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: Inter vs. Intra
- Replies: 85
- Views: 7555
Re: Inter vs. Intra
Intermolecular forces are forces between two molecules, whereas intramolecular forces are forces within a molecule.
- Sun Oct 31, 2021 3:01 pm
- Forum: Ionic & Covalent Bonds
- Topic: Charges in Ionic Bonds
- Replies: 11
- Views: 382
Re: Charges in Ionic Bonds
The numerals are referring to iron. When numerals are in a molecule's name, they will refer to the atom directly before them.
- Sun Oct 31, 2021 2:58 pm
- Forum: Octet Exceptions
- Topic: Valence electrons
- Replies: 19
- Views: 2364
Re: Valence electrons
To find the number of valence electrons for atoms that are not transition metals, you look at what group of the periodic table an atom is in.
- Sun Oct 31, 2021 2:55 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ground and Exited State
- Replies: 11
- Views: 705
Re: Ground and Exited State
These concepts are unrelated. Ground/excited state are terms referring to the energy level of electrons in an atom. Ionic/covalent bonds are types of interactions between atoms in which they share electrons in different ways.
- Sun Oct 31, 2021 2:50 pm
- Forum: Ionic & Covalent Bonds
- Topic: Covalent bonds
- Replies: 21
- Views: 565
Re: Covalent bonds
Sometimes in covalent bonds, one atom in the bond is more electronegative than the other, so it attracts electrons more. Because of this, the electrons are shared unequally. This is similar to ionic bonds, in which one atom donates electrons and the other atom receives them.
- Sun Oct 31, 2021 2:48 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent
- Replies: 21
- Views: 2786
Re: Ionic vs Covalent
Ionic bonds are bonds where electrons are transferred from a metal to a nonmetal. This gives one atom a positive charge (the cation) and one a negative charge (the anion). Covalent bonds are bonds in which electrons are shared between atoms.
- Sun Oct 24, 2021 3:00 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: finding delta x
- Replies: 12
- Views: 2072
Re: finding delta x
The question must give uncertainty in velocity to find the uncertainty in position. The equation for Heisenberg's indeterminacy equation is ΔpΔx≥h/4π, where Δp=mΔv. If the question gives the uncertainty in velocity, you can find the uncertainty of position using Δx≥h/(4πmΔv)). However, if the questi...
- Sun Oct 24, 2021 2:52 pm
- Forum: Photoelectric Effect
- Topic: Equation that does NOT apply to light
- Replies: 10
- Views: 431
Re: Equation that does NOT apply to light
The De Broglie wavelength equation (λ = h/p, where p = mass x velocity) does not apply to light because it requires mass, which light does not have.
- Sun Oct 24, 2021 2:50 pm
- Forum: Photoelectric Effect
- Topic: Equation that does NOT apply to light
- Replies: 10
- Views: 431
Re: Equation that does NOT apply to light
The De Broglie wavelength equation (λ = h/p, where p = mass x velocity) does not apply to light because it requires mass, which light does not have.
- Sun Oct 24, 2021 2:38 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Homework question on 25
- Replies: 18
- Views: 895
Re: Homework question on 25
The configuration with [Ne] in the beginning is the noble gas configuration for the element. Instead of writing out the entire ground-state electron configuration, you can write the most recent noble gas for the element and then write the ground-state electron configuration for the element following...
- Sun Oct 24, 2021 2:34 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: How many orbitals are in a subshell
- Replies: 33
- Views: 6962
Re: How many orbitals are in a subshell
The number of orbitals depends on the subshell the orbitals are in. The s subshell has 1 orbital, the p subshell has 3 orbitals, the d subshell has 5 orbitals, and the f subshell has 7 orbitals.
- Sun Oct 24, 2021 2:29 pm
- Forum: Properties of Electrons
- Topic: Electron and Speed of Light
- Replies: 26
- Views: 1186
Re: Electron and Speed of Light
Electrons have mass so they will not travel at the speed of light. If you need to know the velocity of an electron to solve an equation, it will be given to you or can find it using De Broglie's equation (λ=h/(mass x velocity)).
- Sun Oct 17, 2021 2:49 pm
- Forum: Photoelectric Effect
- Topic: Nodal Plane
- Replies: 7
- Views: 939
Re: Nodal Plane
Nodal planes are regions in an electron cloud where the electron density is 0. S orbitals are shaped like a sphere, so they do not have a nodal plane. P and D orbitals have nodal planes because they have multiple lobes, and the region between these lobes has an electron density of 0.
- Sun Oct 17, 2021 12:47 pm
- Forum: Properties of Electrons
- Topic: Compatible/not compatible waves
- Replies: 5
- Views: 264
Re: Compatible/not compatible waves
Compatible (or constructive) waves are in phase, so they line up and their amplitudes are added to each other, making a larger wave. Incompatible (or destructive) waves are out of phase, so they do not line up and their amplitudes are subtracted from each other, making a smaller wave.
- Sun Oct 17, 2021 12:43 pm
- Forum: Empirical & Molecular Formulas
- Topic: Midterm
- Replies: 66
- Views: 2748
Re: Midterm
Definitely do the textbook problems, because some of them will be on the midterm. Also, go over the audio-visual modules and go to office hours/workshops if you have questions or want help understanding something.
- Sun Oct 17, 2021 12:33 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Constants
- Replies: 13
- Views: 449
Re: Constants
Professor Lavelle allows us to have an equations sheet and a periodic table during the exam, so you will be able to see the constants on this sheet.
- Sun Oct 17, 2021 12:30 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Quantum Numbers
- Replies: 5
- Views: 356
Re: Quantum Numbers
Since I'm assuming the question wants you to identify the unique location of an electron, you need to provide: n-principle quantum number; determines energy and size l- angular momentum quantum number ml- magnetic quantum number; labels different orbitals of a subshell ms- spin magnetic quantum numb...
- Sun Oct 10, 2021 9:05 pm
- Forum: DeBroglie Equation
- Topic: Wave Properties of Electrons
- Replies: 5
- Views: 243
Re: Wave Properties of Electrons
Constructive interference happens when waves are in phase, so they magnify each other. Destructive interference occurs when waves are out of phase and decrease each other, creating a smaller wave. If waves are the same size during destructive interference, they can entirely cancel each other out.
- Sun Oct 10, 2021 8:57 pm
- Forum: Photoelectric Effect
- Topic: Planck's Constant
- Replies: 65
- Views: 3129
Re: Planck's Constant
Since Professor Lavelle uses 6.626x10^-34 for Planck's constant, I think that that's definitely the number you should use when working on problems. By not rounding the earlier on, you get a more accurate final calculation. Also, 6.626 is pretty far off from 6.3, so I imagine that that rounding makes...
- Sun Oct 10, 2021 8:53 pm
- Forum: Empirical & Molecular Formulas
- Topic: Midterm
- Replies: 66
- Views: 2748
Re: Midterm
I've heard that some of the questions on the midterm are taken directly or almost directly from the textbook practice problems, so you should definitely work through those problems. I also personally like making flashcards or Quizlets and rereading through old notes so that they're fresh in my mind.
- Sun Oct 10, 2021 8:50 pm
- Forum: Properties of Electrons
- Topic: Energy Levels [ENDORSED]
- Replies: 11
- Views: 447
Re: Energy Levels [ENDORSED]
The levels would not be the same for each atom, because atoms of different elements do not have the same number of protons in their nucleus.
- Fri Oct 08, 2021 2:09 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Audio Visual Focus Topics
- Replies: 3
- Views: 176
Re: Audio Visual Focus Topics
I was also wondering whether the audio visual focus topics covered the whole quantum realm section, or whether they only covered the topics we learned this week.
- Tue Sep 28, 2021 10:54 pm
- Forum: Significant Figures
- Topic: Sig fig - round or truncate
- Replies: 4
- Views: 234
Re: Sig fig - round or truncate
Generally, I believe rounding is the way to go, since that is what's typically done in math.
- Tue Sep 28, 2021 10:51 pm
- Forum: Balancing Chemical Reactions
- Topic: Labeling Atoms and Molecules
- Replies: 7
- Views: 278
Re: Labeling Atoms and Molecules
I don't think it's important at the moment, though it is important for net ionic equations. Personally, I have not found it necessary to label the state of matter of atoms and molecules to solve the questions we've been given so far.
- Tue Sep 28, 2021 8:44 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Units and Molarity
- Replies: 10
- Views: 385
Re: Units and Molarity
I believe Professor Lavelle only changed the units back to mL so that it would make sense in a lab setting, since generally you would not tell someone to measure out a tiny fraction of a liter, but rather that amount in milliliters. He stated in the lecture that it was not necessary to convert the f...
- Tue Sep 28, 2021 8:40 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lecture 3 Recorded Classes
- Replies: 2
- Views: 170
Re: Lecture 3 Recorded Classes
Hi! I'm pretty sure if you go to the UCLA CCLE website and you scroll to "Media Resources" the recordings of the Friday and Monday lectures should be there. Hope this helps! That's where I've been finding the lectures! If you're taking this class online and not in-person, the lectures are...
- Tue Sep 28, 2021 8:35 pm
- Forum: Student Social/Study Group
- Topic: Culinary Chemistry
- Replies: 239
- Views: 47993
Re: Culinary Chemistry
Oh wow! Very interesting to see you put Chem to action and apply it to real world stuff! I suck at cooking but maybe once I get a little further in Chem, I'll be the next Gordon Ramsey??? If you're just getting started I would recommend YouTube for some great instruction in kitchen techniques. Chan...
- Tue Sep 28, 2021 8:32 pm
- Forum: Student Social/Study Group
- Topic: Fave food
- Replies: 266
- Views: 55950
Re: Fave food
I really like green chile enchiladas, especially because they remind me of home.
- Tue Sep 28, 2021 8:31 pm
- Forum: Significant Figures
- Topic: How far through the decimals of an element's molar mass do you have to go?
- Replies: 9
- Views: 1080
Re: How far through the decimals of an element's molar mass do you have to go?
If the smallest number of significant figures provided in the information given was 3, then that is how many significant figures you should use for all of your calculations, as well as your answer. You should always use the same number of significant figures as that of the value provided with the le...
- Tue Sep 28, 2021 8:27 pm
- Forum: Significant Figures
- Topic: Why does 100 have only one significant figure?
- Replies: 12
- Views: 3050
Re: Why does 100 have only one significant figure?
It only has 1 significant figure because there is no decimal point at the end. 100. would have three significant figures, as would 101.