Search found 52 matches

by AndreiRekesh1I
Sat Dec 07, 2019 9:32 pm
Forum: Biological Examples
Topic: memorizing examples
Replies: 3
Views: 39

Re: memorizing examples

Heme complexes, myoglobin, and hemoglobin (and their function) may be important.
by AndreiRekesh1I
Sat Dec 07, 2019 9:29 pm
Forum: Biological Examples
Topic: chemotherapy drugs
Replies: 4
Views: 43

Re: chemotherapy drugs

Cisplatin in particular has 2 Cl on the same side, which allows it to bind to base pairs and stop DNA replication.
by AndreiRekesh1I
Sat Dec 07, 2019 9:23 pm
Forum: Administrative Questions and Class Announcements
Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
Replies: 111
Views: 5006

Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]

For #1c on mini marshmallow, how do you know to choose NH4+ and not NO3- for the net ionic equation? Since they're both weak acids and bases H + NO3 becomes HNO3, which is a strong acid and would be more inclined to dissociate completely rather than be put together (the equation would make more sen...
by AndreiRekesh1I
Sat Dec 07, 2019 5:50 pm
Forum: Hybridization
Topic: How to recognize
Replies: 1
Views: 95

Re: How to recognize

Hybridization usually comes in to explain when an atom has fewer valence electrons by nature than regions of electron density, like bonds and lone pairs.
by AndreiRekesh1I
Sat Dec 07, 2019 5:44 pm
Forum: Naming
Topic: bis-,tris-,tetrakis-
Replies: 2
Views: 31

Re: bis-,tris-,tetrakis-

When the ligand is any kind of polydentate
by AndreiRekesh1I
Sun Dec 01, 2019 7:11 pm
Forum: Lewis Acids & Bases
Topic: Lewis and Bronsted
Replies: 2
Views: 25

Re: Lewis and Bronsted

Lewis acids are electron acceptors and Lewis bases are electron donors. Bronsted acids are hydrogen ion donors and Bronsted bases are hydrogen ion acceptors.
by AndreiRekesh1I
Sun Dec 01, 2019 7:09 pm
Forum: Lewis Acids & Bases
Topic: Arrhenius
Replies: 3
Views: 42

Re: Arrhenius

So far he hasn't gone over Arrhenius bases, and the homework problems don't seem to cover them either.
by AndreiRekesh1I
Sun Dec 01, 2019 7:08 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: differences in acid/base strength
Replies: 1
Views: 45

Re: differences in acid/base strength

When there are more than 2 atoms, there's usually an Oxygen in there somewhere, like HOBr, HOCl, etc. The ones that are more likely to dissociate depend on how much the non-O component of the anion (which would be Br and Cl in these cases) pull electrons towards it, which depends on electronegativit...
by AndreiRekesh1I
Sun Dec 01, 2019 7:00 pm
Forum: Naming
Topic: Problem C.3 part (d)
Replies: 2
Views: 44

Re: Problem C.3 part (d)

Na[Fe(OH2)2(C2O4)2] - Since sodium is the cation, it is written in front, before the complex in brackets. Fe is the cation within the complex, so it's written before any ligands in the brackets. Water (referred to by diaqua) and oxalate (referred to by "bisoxalato", because the -o is added...
by AndreiRekesh1I
Sun Dec 01, 2019 6:53 pm
Forum: General Science Questions
Topic: Week 10 Classes
Replies: 7
Views: 168

Re: Week 10 Classes

I think Friday is a review day.
by AndreiRekesh1I
Sun Dec 01, 2019 6:51 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Donor electrons of Ligands
Replies: 1
Views: 25

Re: Donor electrons of Ligands

Donor atoms are atoms that can donate an electron pair (so anything with a lone pair). The nitrogens in that molecule are likely the donor atoms because they have lone pairs.
by AndreiRekesh1I
Sun Nov 24, 2019 11:50 pm
Forum: Bond Lengths & Energies
Topic: Boiling Point
Replies: 4
Views: 169

Re: Boiling Point

You can use london forces to compare boiling point if the molecules are both nonpolar, because then you know there's no dipole-dipole at play.
by AndreiRekesh1I
Sun Nov 24, 2019 11:47 pm
Forum: Resonance Structures
Topic: Resonance vs Isomers
Replies: 2
Views: 116

Re: Resonance vs Isomers

Isomers are made up of the same atoms but completely different structures, but resonance doesn't mean there are multiple ways to structure the molecule (since the actual bond length and structure is just the average of the resonance structures).
by AndreiRekesh1I
Sun Nov 24, 2019 11:44 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond Order
Replies: 2
Views: 89

Re: Bond Order

Then the atoms being compared are not bonded.
by AndreiRekesh1I
Sun Nov 24, 2019 11:42 pm
Forum: Electronegativity
Topic: Hydrogen
Replies: 6
Views: 156

Re: Hydrogen

There are fewer protons in its nucleus. Flourine also forms much stronger bonds with other atoms (which is one part of how electronegativity can be defined).
by AndreiRekesh1I
Sun Nov 24, 2019 11:38 pm
Forum: Trends in The Periodic Table
Topic: Octet Expansion
Replies: 5
Views: 146

Re: Octet Expansion

Period 3, because that's when D-orbitals become available to accommodate extra electrons.
by AndreiRekesh1I
Sun Nov 17, 2019 10:50 pm
Forum: Student Social/Study Group
Topic: Bond Angles
Replies: 6
Views: 106

Re: Bond Angles

If necessary we could probably reason that H2O has a smaller bond angle than NH3 because the O has two lone pairs, and the interactions between them are stronger than those between bonded atoms so they push the bonds further and squeeze the angle smaller.
by AndreiRekesh1I
Sun Nov 17, 2019 10:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Naming the Molecular Shapes
Replies: 7
Views: 111

Re: Naming the Molecular Shapes

The names are kind of based on what the shapes look like (i.e. trigonal planar is a flat triangle "plane", and trigonal bipyramidal is two three-sided pyramids stacked base to base).
by AndreiRekesh1I
Sun Nov 17, 2019 10:43 pm
Forum: Trends in The Periodic Table
Topic: Trend for Polarizability
Replies: 6
Views: 160

Re: Trend for Polarizability

It increases as you go left to right and up to down, because it increases depending on how many valence electrons there are and how far away they are from the nucleus.
by AndreiRekesh1I
Sun Nov 17, 2019 10:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Instantaneous Dipole versus Induced Dipole
Replies: 4
Views: 67

Re: Instantaneous Dipole versus Induced Dipole

Induced dipole implies that it's being caused by another atom but instantaneous dipoles can happen just from the arrangement and movement of electrons around the nucleus (more on one side than the other at a certain point in time).
by AndreiRekesh1I
Sun Nov 17, 2019 10:28 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: size and intermolecular forces
Replies: 1
Views: 16

Re: size and intermolecular forces

They usually have more electrons so IMFs like dispersion are stronger. Also since electrons are further from the nucleus they can polarize more easily.
by AndreiRekesh1I
Sun Nov 17, 2019 10:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE Formula
Replies: 4
Views: 60

Re: AXE Formula

It's the best way, but you could draw it specifically to focus on the arrangements of bonds and lone pairs on the center atom because that's what AXE tracks anyway.
by AndreiRekesh1I
Sun Nov 10, 2019 10:07 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 5
Views: 50

Re: Electronegativity

Typically the fewer electrons an atom needs to complete a full valence shell, the more electronegative it is.
by AndreiRekesh1I
Sun Nov 10, 2019 10:04 pm
Forum: Student Social/Study Group
Topic: Chem 14B
Replies: 10
Views: 214

Re: Chem 14B

I am, I'm in the 3pm lecture if I can get the class
by AndreiRekesh1I
Sun Nov 10, 2019 9:59 pm
Forum: Electronegativity
Topic: Atom size
Replies: 16
Views: 648

Re: Atom size

They're not directly correlated but as electronegativity increases across the periodic table so do the number of protons in the nucleus so atom size goes down, as the protons attract the electrons more tightly. As we go down the periodic table, electronegativity decreases because electrons are furth...
by AndreiRekesh1I
Sun Nov 10, 2019 9:55 pm
Forum: Dipole Moments
Topic: Dipole moments
Replies: 3
Views: 40

Re: Dipole moments

Dipole moment is how polar a bond between two atoms is. It's calculated by the magnitude of the charges of the two atoms multiplied by the distance between them.
by AndreiRekesh1I
Sun Nov 10, 2019 9:53 pm
Forum: Coordinate Covalent Bonds
Topic: Coordinate covalent bonds
Replies: 7
Views: 209

Re: Coordinate covalent bonds

Coordinate covalent bonds are where both electrons in the bond are supplied by the same atom, sometimes represented by an arrow drawn from the donator to the receiver instead of a line for regular covalent bonds.
by AndreiRekesh1I
Sun Nov 03, 2019 11:13 pm
Forum: General Science Questions
Topic: Study Tactics
Replies: 5
Views: 101

Re: Study Tactics

I think doing all the problems he gives instead of a few probably gives a more complete picture of how the test will be, also reading over and understanding the bullet pointed concepts Lavelle outlined on his learning outcome sheets should help.
by AndreiRekesh1I
Sun Nov 03, 2019 10:59 pm
Forum: Ionic & Covalent Bonds
Topic: covalent character
Replies: 4
Views: 57

Re: covalent character

I guess the other definition would be, if you don't know what the bond type is, it's determined by electronegativity difference between atoms (whether the bond has ionic or covalent character).
by AndreiRekesh1I
Sun Nov 03, 2019 10:58 pm
Forum: Ionic & Covalent Bonds
Topic: covalent character
Replies: 4
Views: 57

Re: covalent character

It's the quality of ionic bonds to sometimes share electrons (usually because the anion is strong enough to pull electrons towards it), the way covalent bonds would.
by AndreiRekesh1I
Sun Nov 03, 2019 10:53 pm
Forum: Lewis Structures
Topic: 2C.7
Replies: 1
Views: 21

Re: 2C.7

Since iodine is one of the elements that can break the Octet Rule, it's five chlorines around the iodine.
by AndreiRekesh1I
Sun Nov 03, 2019 10:51 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers
Replies: 4
Views: 172

Re: Quantum Numbers

IIRC l must be at most one fewer than n in all cases, and the absolute value of ml must be at most equal to l.
by AndreiRekesh1I
Sun Oct 27, 2019 9:21 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Finding Most Stable Structure
Replies: 9
Views: 92

Re: Finding Most Stable Structure

When formal charge on atoms (usually the center atom is most important) is zero, then that configuration is the most stable.
by AndreiRekesh1I
Sun Oct 27, 2019 9:15 pm
Forum: Formal Charge and Oxidation Numbers
Topic: 0 Formal Charge
Replies: 2
Views: 38

Re: 0 Formal Charge

A formal charge of 0 generally means the atom is more stable because it compares the number of lone pairs and half the bonded electrons to the number of electrons the atom would have in its natural free state. Having that number be as close to zero as possible would mean that the atom in its bonded ...
by AndreiRekesh1I
Sun Oct 27, 2019 9:10 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 6
Views: 71

Re: Electronegativity

You can think of electronegativity as how "hungry" an atom is for electrons, usually because it wants to complete its outer valence shell. Since the furthest right elements of the periodic table are the noble gases, which are stable and already have completed valence shells, they aren't ve...
by AndreiRekesh1I
Sun Oct 27, 2019 9:04 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 4
Views: 56

Re: Resonance Structures

This isn't true for all cases but usually resonance structures can be drawn whenever the diagram of a molecule has different types of bonds to a center atom whose locations are interchangeable. All the possible combinations of how these bonds can be arranged would be the number of resonance structur...
by AndreiRekesh1I
Sun Oct 27, 2019 8:54 pm
Forum: Electronegativity
Topic: Polarity
Replies: 5
Views: 63

Re: Polarity

The difference in electronegativity (or at least the absolute value) between atoms in a compound provides a rough measure of its polarity. This helps differentiate between nonpolar covalent, polar covalent, and ionic bonds.
by AndreiRekesh1I
Thu Oct 17, 2019 11:50 pm
Forum: Photoelectric Effect
Topic: Quick Question
Replies: 3
Views: 71

Re: Quick Question

Ionization energy is the energy required to remove an electron from a single atom, but threshold energy refers to the amount of energy required to remove an electron from a metal surface via light (like in the photoelectric effect).
by AndreiRekesh1I
Thu Oct 17, 2019 11:37 pm
Forum: Quantum Numbers and The H-Atom
Topic: Orbitals in an H-Atom
Replies: 3
Views: 58

Re: Orbitals in an H-Atom

Hydrogen only has one electron, I think it's the interactions between electrons that cause these differences in energy levels.
by AndreiRekesh1I
Thu Oct 17, 2019 11:24 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Heisenberg's Indeterminancy Equations
Replies: 2
Views: 37

Re: Heisenberg's Indeterminancy Equations

I think the second equation you're referring to is the definition of momentum, the first one is related to indeterminacy
by AndreiRekesh1I
Thu Oct 17, 2019 4:40 pm
Forum: Properties of Light
Topic: 1A7b textbook solution typo?
Replies: 5
Views: 85

Re: 1A7b textbook solution typo?

I got the same answer; I assume it's a typo because it's not even the unit the problem is asking for.
by AndreiRekesh1I
Thu Oct 17, 2019 4:36 pm
Forum: DeBroglie Equation
Topic: Frequency and wavelength
Replies: 2
Views: 60

Re: Frequency and wavelength

If the object isn't some sort of electromagnetic radiation you can't really assume it travels at the speed of light and find the frequency that way.
by AndreiRekesh1I
Thu Oct 10, 2019 11:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Where do we check our grades?
Replies: 3
Views: 91

Re: Where do we check our grades?

Will we not be able to know our "participation" grade for posting on this website until the end of the quarter or are there updates?
by AndreiRekesh1I
Thu Oct 10, 2019 11:04 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 Grading
Replies: 12
Views: 447

Re: Test 1 Grading

I'm curious to see how lenient the graders are with partial credit
by AndreiRekesh1I
Thu Oct 10, 2019 10:42 pm
Forum: Properties of Light
Topic: Quantum mechanics description of light
Replies: 2
Views: 45

Re: Quantum mechanics description of light

Wavelength is inversely proportional to energy, so shorter wavelength (represented by lambda) would have enough energy to eject e- from a metal while a higher wavelength might not.
by AndreiRekesh1I
Thu Oct 10, 2019 10:40 pm
Forum: Properties of Light
Topic: Wavelength help
Replies: 3
Views: 46

Re: Wavelength help

Wavelength is inversely proportional to energy, as wavelength decreases energy increases.
by AndreiRekesh1I
Wed Oct 09, 2019 8:21 pm
Forum: Properties of Light
Topic: Constants in the Quantum World
Replies: 6
Views: 76

Re: Constants in the Quantum World

In my experience, remembering not only the values of constants but also the molar masses of common elements saves a lot of time.
by AndreiRekesh1I
Thu Oct 03, 2019 5:16 pm
Forum: Significant Figures
Topic: sig figs in calculations
Replies: 4
Views: 64

Re: sig figs in calculations

It's best to use them only in your final answer, otherwise rounding at each step may cause your final answer to be less accurate. The final answer will also be the only one where graders actually care about the correct number of sigfigs.
by AndreiRekesh1I
Thu Oct 03, 2019 5:12 pm
Forum: Limiting Reactant Calculations
Topic: Homework Week 1
Replies: 18
Views: 310

Re: Homework Week 1

serenabirkhoff_1K wrote:I understand it is 5 problems each week but how is it graded? Is it completely by accuracy?


I don't think they're graded by accuracy, at least that's what my TA said
by AndreiRekesh1I
Thu Oct 03, 2019 5:04 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Lab experiments- accuracy vs precision
Replies: 7
Views: 147

Re: Lab experiments- accuracy vs precision

Often in labs you can know how accurate your results are by comparing the experimental values to theoretical ones, and how precise they are by repeating the same experiment multiple times and comparing the results to one another.
by AndreiRekesh1I
Wed Oct 02, 2019 9:54 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Reaction
Replies: 6
Views: 112

Re: Balancing Chemical Reaction

For combustion reactions in particular, I find that balancing oxygen last is easiest.
by AndreiRekesh1I
Wed Oct 02, 2019 8:22 pm
Forum: SI Units, Unit Conversions
Topic: Sig figs
Replies: 18
Views: 323

Re: Sig figs

It's probably best to use the number of sig figs in the givens.

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