Search found 34 matches

by IScarvie 1I
Sun Nov 17, 2019 11:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Understanding longer molecule VSPER shapes.
Replies: 3
Views: 11

Re: Understanding longer molecule VSPER shapes.

When the molecule is a long chain, you determine the shape of each portion of the chain around each central molecule separately
by IScarvie 1I
Sun Nov 17, 2019 11:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Naming the Molecular Shapes
Replies: 7
Views: 25

Re: Naming the Molecular Shapes

The names are mostly pretty intuitive, it's usually most helpful to envision the molecule in a three-dimensional space. I also use flashcards for some of the harder ones like seesaw.
by IScarvie 1I
Sun Nov 17, 2019 11:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Instantaneous Dipole versus Induced Dipole
Replies: 4
Views: 14

Re: Instantaneous Dipole versus Induced Dipole

Instantaneous dipoles are momentary moments where one side of the molecule will be more electronegative than the other as electrons move around the nuclei. When two nonpolar molecules are next to each other, these instantaneous dipoles form induced dipoles, as the temporarily negative side of one is...
by IScarvie 1I
Fri Nov 15, 2019 3:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: varying VSEPRs
Replies: 7
Views: 29

Re: varying VSEPRs

No, the shape doesn't vary
by IScarvie 1I
Fri Nov 15, 2019 3:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 6
Views: 39

Re: Bond Angles

If you can remember what the shape looks like three-dimensionally, most of the angles (except 109.5) are pretty intuitive. For example, for the trigonal bipyramidal shape in a 3d space, you can see visually where the 90 and 180-degree angles are.
by IScarvie 1I
Mon Nov 11, 2019 5:21 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: forces and boiling points
Replies: 6
Views: 15

Re: forces and boiling points

Another important thing to remember is that CH4 does not form hydrogen bonds because C is not electronegative enough. It follows the normal dispersion rules, and Cl has more electrons than H
by IScarvie 1I
Mon Nov 11, 2019 5:17 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: melting points
Replies: 6
Views: 34

Re: melting points

Another way to think about it is that O is more electronegative than S, so its dipole moments are more dramatic than H2S's. The positive and negative ends form stronger bonds because of it.
by IScarvie 1I
Mon Nov 11, 2019 5:14 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: The Strength of Hydrogen Bonding
Replies: 4
Views: 16

Re: The Strength of Hydrogen Bonding

since F, O, and N are the three most electronegative elements, and H is very positive, hydrogen bonds are very strong and hard to break apart
by IScarvie 1I
Mon Nov 11, 2019 5:11 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: types of intermolecular forces
Replies: 5
Views: 18

Re: types of intermolecular forces

You can tell if a molecule is polar if one side is more electronegative than the other. I like to think of dipole-dipole bonds like magnets; if two things with positive and negative sides are close together, the positive will bind with the negative.
by IScarvie 1I
Mon Nov 04, 2019 1:35 am
Forum: Resonance Structures
Topic: Resonance Structure
Replies: 2
Views: 26

Re: Resonance Structure

When you have a Lewis dot structure where a double bond could be placed with a different atom of the same element and the formal charges would not change, you draw the structure each way it is possible for it to form and draw arrows between the structures, showing that they are interchangeable
by IScarvie 1I
Mon Nov 04, 2019 1:31 am
Forum: Dipole Moments
Topic: Dipole Arrow
Replies: 5
Views: 24

Re: Dipole Arrow

The arrow point should point towards the negative dipole, the + should point towards the positive.
by IScarvie 1I
Mon Nov 04, 2019 1:30 am
Forum: Octet Exceptions
Topic: Biological Impacts of Radicals
Replies: 4
Views: 22

Re: Biological Impacts of Radicals

There is a biological theory of aging that revolves around free radicals. Basically, it’s thought that as the radicals bind to parts of the cell they wear it down over time, especially DNA.
by IScarvie 1I
Mon Nov 04, 2019 1:28 am
Forum: Octet Exceptions
Topic: Lewis Acids and Bases?
Replies: 11
Views: 48

Re: Lewis Acids and Bases?

A Lewis acid is a lone pair acceptor, and a Lewis pair is a lone pair donor. I believe they are similar to covalent bonds, except they typically form as separate molecules and join to fulfill their individual needs
by IScarvie 1I
Mon Nov 04, 2019 1:25 am
Forum: Dipole Moments
Topic: Polar Covalent Bonds
Replies: 2
Views: 15

Re: Polar Covalent Bonds

Some elements are more electronegative than others; for example, Fluorine has more protons in its nucleus than Carbon, so it will pull on electrons in a covalent bond more strongly.
by IScarvie 1I
Sun Oct 27, 2019 9:58 am
Forum: Ionic & Covalent Bonds
Topic: How are lewis structures filled?
Replies: 6
Views: 39

Re: How are lewis structures filled?

I typically give each atom around the center an octet first and adjust from there with double bonds and single pairs in the center, but I think both ways work
by IScarvie 1I
Sun Oct 27, 2019 9:54 am
Forum: Ionic & Covalent Bonds
Topic: Double bond placement
Replies: 15
Views: 68

Re: Double bond placement

In general, hydrogen likes to have one bond, oxygen likes two, nitrogen likes three, and carbon likes four. When you decide where to put double bonds or triple bonds, arrange them so that the most atoms have 0 formal charge and all the electrons are used, which usually follows the rules above.
by IScarvie 1I
Sun Oct 27, 2019 9:51 am
Forum: Ionic & Covalent Bonds
Topic: Explaining periodic trends
Replies: 3
Views: 24

Re: Explaining periodic trends

I think it depends on the element but in general, I think I remember size and shielding being more influential on atomic radius than electrostatic interactions between the protons and the nucleus. However, both are important to consider, and I don't think there were any questions in the homework whe...
by IScarvie 1I
Sun Oct 27, 2019 9:45 am
Forum: Resonance Structures
Topic: Bond lengths
Replies: 5
Views: 22

Re: Bond lengths

I believe he said in our lecture on Friday that we don't need to know how to find the bond lengths in this class, just that double bonds are shorter than single bonds between the same two elements, and bonds in resonant structures are between those two lengths.
by IScarvie 1I
Sun Oct 27, 2019 9:43 am
Forum: Lewis Structures
Topic: Drawing Lewis Structure
Replies: 6
Views: 25

Re: Drawing Lewis Structure

I believe in this class you have to draw them in order to ensure that each atom gets the right number of electrons in the structure
by IScarvie 1I
Sun Oct 20, 2019 2:08 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Overlapping
Replies: 4
Views: 31

Re: Overlapping

Yes, they do overlap, especially in electrons with more shells further from the nucleus. Like the last responder said, the probability isn't necessarily doubled, but it is influenced by the extra shell
by IScarvie 1I
Sun Oct 20, 2019 2:06 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Inner e- and Outer e-
Replies: 14
Views: 69

Re: Inner e- and Outer e-

Inner electrons feel more electrostatic attraction from the positively charged nucleus. This charge is stronger the further down the periodic table you go, so the inner electrons in those atoms are closer to the nucleus. Outer electrons are shielded from this pull by the inner electrons, so they are...
by IScarvie 1I
Sun Oct 20, 2019 2:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 6
Views: 25

Re: Nodal Planes

Nodal planes are planes in the p, d, and f orbitals with zero electron density probability. In other words, there is no likelihood of finding an electron in that spot.
by IScarvie 1I
Sun Oct 20, 2019 2:00 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Hund's rule and Pauli Exclusion Principle
Replies: 14
Views: 72

Re: Hund's rule and Pauli Exclusion Principle

You use Hund's rule and the Pauli Exclusion Principle together to write the ground-state electron configuration of an atom. Hund's rule tells you to fill in orbitals with one electron each with parallel spin before doubling up, and the Pauli Exclusion Principle tells you to give the paired electrons...
by IScarvie 1I
Sun Oct 20, 2019 1:56 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Structure of electrons
Replies: 5
Views: 22

Re: Structure of electrons

An orbital has three quantum numbers, while a shell is only defined by n
by IScarvie 1I
Thu Oct 10, 2019 2:14 pm
Forum: Einstein Equation
Topic: Numbers to memorize [ENDORSED]
Replies: 37
Views: 996

Re: Numbers to memorize [ENDORSED]

It's nice to have them memorized because they are used often, but they will be given to us on tests
by IScarvie 1I
Thu Oct 10, 2019 2:12 pm
Forum: *Black Body Radiation
Topic: Black Body
Replies: 4
Views: 2005

Re: Black Body

Black bodies are an idealization; an actual black body that emits and absorbs all frequencies does not exist. Stars are approximately like black bodies, but not exactly
by IScarvie 1I
Thu Oct 10, 2019 2:08 pm
Forum: Properties of Light
Topic: Minimum Frequency
Replies: 2
Views: 32

Re: Minimum Frequency

If an electron is removed with zero kinetic energy or the energy of the light is the same as the energy required to remove an electron, you can use the energy of that light to calculate the minimum frequency
by IScarvie 1I
Thu Oct 10, 2019 2:05 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 4
Views: 34

Re: Speed of Light

Yes, it only applies in a vacuum, but unless the question specifies otherwise, I think you can assume it applies
by IScarvie 1I
Thu Oct 10, 2019 2:03 pm
Forum: Photoelectric Effect
Topic: Kinetic Energy from the Photoelectric Effect
Replies: 5
Views: 45

Re: Kinetic Energy from the Photoelectric Effect

In a photoelectric experiment, the kinetic energy is also measured by a detector
by IScarvie 1I
Thu Oct 03, 2019 12:41 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding for Formulas
Replies: 8
Views: 73

Re: Rounding for Formulas

This came up in our discussion today, and generally if it's within .1 of the whole integer you want to round to it's ok. You could round 2.9 to 3, for example.
by IScarvie 1I
Thu Oct 03, 2019 12:32 pm
Forum: Molarity, Solutions, Dilutions
Topic: Periodic Table & Formulas
Replies: 2
Views: 48

Re: Periodic Table & Formulas

My TA said in discussion today that we will be provided with a periodic table and an equation sheet. Hope that helps!
by IScarvie 1I
Thu Oct 03, 2019 12:28 pm
Forum: Balancing Chemical Reactions
Topic: State Symbols in Equations
Replies: 8
Views: 70

Re: State Symbols in Equations

It's a good idea to start writing the state symbols now so it becomes a habit. They are very useful for understanding what is physically happening in the reaction, and they may be required later on.
by IScarvie 1I
Thu Oct 03, 2019 12:25 pm
Forum: Balancing Chemical Reactions
Topic: Products of combustion reactions
Replies: 7
Views: 45

Re: Products of combustion reactions

I believe when you are told to write an equation for a combustion reaction, you assume the products will be CO2 and H2O. However, sometimes you will be given other products, like in homework problem M19.
by IScarvie 1I
Thu Oct 03, 2019 10:03 am
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula Purpose
Replies: 13
Views: 103

Re: Empirical Formula Purpose

The empirical formula is not used in chemical equations because it only shows the simplest ratio of the atoms in the molecule, not the actual number of atoms present. It can be used, along with the molar mass of the molecule, to find the molecular formula, which does tell you the number of atoms pre...

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