Search found 31 matches

by Nina_A_Section1E
Wed Jun 13, 2018 2:51 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: French Toast #25 [ENDORSED]
Replies: 1
Views: 124

Re: French Toast #25 [ENDORSED]

Cl has a -1 charge, so 2 of them make make a -2 charge, and since NH3 is a neutral atom, you need the Pt to balance the Cl charges by giving it a +2 oxidation state
by Nina_A_Section1E
Wed Jun 13, 2018 9:35 am
Forum: Trends in The Periodic Table
Topic: Electron affinity: C vs. N
Replies: 1
Views: 86

Electron affinity: C vs. N

Which has a higher electron affinity? I'm getting different answers from different sources
According to the trend, N would be higher, but some sources said because N has half its subshell filled, it's more stable than C that only has 2/6 e- in the p orbital - which is correct?
by Nina_A_Section1E
Thu Jun 07, 2018 9:32 pm
Forum: Bond Lengths & Energies
Topic: Breaking/ Forming Bonds
Replies: 2
Views: 115

Re: Breaking/ Forming Bonds

Forming bonds releases energy because when bonds are formed, octets are filled, and it puts atoms at a lower energy state.

Because bonds are attractions between atoms, it takes energy to break them, because their tendency is to want to stay together.
by Nina_A_Section1E
Fri Jun 01, 2018 12:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: regions of e- density
Replies: 4
Views: 93

Re: regions of e- density

Yes, regions of e- density can either be bonds or lone pairs, and both affect the shape of a molecule. Lone pairs especially affect structure because they have large repulsion forces, and they can decrease bond angles by repelling atoms away more strongly than a normal atom would do.
by Nina_A_Section1E
Fri Jun 01, 2018 12:24 pm
Forum: Dipole Moments
Topic: London vs. Dipole
Replies: 3
Views: 240

Re: London vs. Dipole

https://socratic.org/questions/5a64204ab72cff7b83554c78 This site has a really good summary! London forces/Van der Waal's forces is completely random and unrelated to electronegativity. Sometimes electrons happen to be closer to one molecule at a given time, creating contemporary partial negative ch...
by Nina_A_Section1E
Thu May 31, 2018 5:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double bond
Replies: 3
Views: 59

Re: Double bond

A sigma bond is a covalent bond which is formed by the head on overlap of two atomic orbitals. A Pi bond is a covalent bond which is formed by the side-to-side overlap of two atomic orbitals. Sigma bonds are relatively stronger when compared with pi bonds. So, pi bonds are easily broken while sigma ...
by Nina_A_Section1E
Thu May 24, 2018 1:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance
Replies: 7
Views: 174

Re: Resonance

A molecule can have a resonance structure when certain bond(s), usually a double or triple bond, can be placed in multiple locations around the central atom without changing the overall formal charges. It goes into more depth here! https://socratic.org/questions/how-can-i-determine-if-and-when-a-mol...
by Nina_A_Section1E
Thu May 24, 2018 1:47 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge W/ Radicals
Replies: 2
Views: 302

Re: Formal Charge W/ Radicals

Same formula of Formal Charge = Valence - (Lone Pair e- + 1/2Bonded e-), so for the # of lone pair e-, it would just be an odd number when dealing with radicals
by Nina_A_Section1E
Wed May 23, 2018 4:07 pm
Forum: Lewis Structures
Topic: Writing Chemical Formulas- HW Question 3.25
Replies: 2
Views: 78

Re: Writing Chemical Formulas- HW Question 3.25

Mg commonly forms +2 ions since it has 2 valence e-, and Arsenic has 5 valence e-, so it needs 3 to fill its shell, according to the octet rule. So both elements' needs are met, use 3 Mg and 2AS to make As2Mg3!
by Nina_A_Section1E
Mon May 14, 2018 3:03 pm
Forum: Lewis Structures
Topic: Corbon Monoxide
Replies: 5
Views: 181

Re: Corbon Monoxide

The Lewis structure for CO has 10 valence electrons. For the CO Lewis structure you'll need a triple bond between the Carbon and Oxygen atoms in order to satisfy the octets of each atom while still using the 10 valence electrons available for the CO molecule https://terpconnect.umd.edu/~wbreslyn/che...
by Nina_A_Section1E
Mon May 14, 2018 11:54 am
Forum: Lewis Structures
Topic: Octet Rule [ENDORSED]
Replies: 3
Views: 96

Re: Octet Rule [ENDORSED]

It's ok to break the octet rule when: 1. there are an odd number of valence electrons 2. there are too few valence electrons 3. there are too many valence electrons It lays it out nicely here! https://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Chemical_Bonding/Lewis_Theory_of_Bondin...
by Nina_A_Section1E
Mon May 14, 2018 11:52 am
Forum: Lewis Structures
Topic: Formal Energies [ENDORSED]
Replies: 2
Views: 79

Re: Formal Energies [ENDORSED]

Formal energies/charges help you find the most stable Lewis structure, as well as confirm that it is a correct structure, because the addition of all of the formal charges of the atoms in a molecule should equal the overall charge of the molecule
by Nina_A_Section1E
Thu May 10, 2018 2:31 pm
Forum: Resonance Structures
Topic: Resonance Structures and Formal charges
Replies: 7
Views: 203

Re: Resonance Structures and Formal charges

Resonance structures are just different, equally stable, Lewis structures for an atom, so they all have the same charge!
by Nina_A_Section1E
Thu May 10, 2018 1:32 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: energy emitted
Replies: 2
Views: 119

Re: energy emitted

Right, the first equation solving for frequency is just a manipulation of the second equation that finds levels at different energy shells!
by Nina_A_Section1E
Tue May 08, 2018 9:29 pm
Forum: Photoelectric Effect
Topic: Midterm Practice Test #4b
Replies: 3
Views: 465

Re: Midterm Practice Test #4b

How did you get this answer?
by Nina_A_Section1E
Sun May 06, 2018 4:07 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radii
Replies: 2
Views: 100

Atomic Radii

1. Can an e- get excited from 2s to 2p? Or when it gets excited, will it only jump n shells, not subshells?

2. If an e- goes from 2s to 2p, does its radius increase, or no because it's still in shell 2?
by Nina_A_Section1E
Thu May 03, 2018 11:14 am
Forum: Quantum Numbers and The H-Atom
Topic: Energy of electron vs. Energy Level
Replies: 2
Views: 108

Re: Energy of electron vs. Energy Level

I believe the energy of the electron increases, because when the e- is so far from the nucleus that it's unattached, energy level is 0, and as the e- comes closer and closer to the nucleus, its energy becomes more and more negative, losing energy. Therefore, the farther away it moves from the nucleu...
by Nina_A_Section1E
Thu May 03, 2018 9:21 am
Forum: Lewis Structures
Topic: Help on 3.35
Replies: 2
Views: 67

Re: Help on 3.35

https://youtu.be/-gCVrBPkk4A This video goes through how to write the structure for the BrO- ion
https://youtu.be/skbI-Wu1XME This video goes through the structure for the NH2- ion
They're both less than a minute!
by Nina_A_Section1E
Thu May 03, 2018 9:19 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Clarification on magnetic quantum number
Replies: 6
Views: 174

Re: Clarification on magnetic quantum number

Yes, l refers to the subshells: s, p, d, f, and ml refers to the orbitals within the subshells, so for p when l = 1, ml = -1, 0, or 1 representing px, py, and pz orbitals
by Nina_A_Section1E
Thu Apr 26, 2018 2:45 pm
Forum: Properties of Electrons
Topic: Spin Magnetic Quantum Number
Replies: 2
Views: 119

Re: Spin Magnetic Quantum Number

Since e- spins on its axis it has an angular momentum and orbital angular momentum, the spin magnetic quantum number describes the angular momentum of the e-. This is a vector, which is why it has magnitude (1/2) and a direction (+/-) Since each orbital holds 2 e-, 1 will have a spin +1/2, and the o...
by Nina_A_Section1E
Thu Apr 26, 2018 2:31 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Constant [ENDORSED]
Replies: 6
Views: 190

Re: Rydberg Constant [ENDORSED]

3.29 x 10^15 is most helpful to us in the equations we're doing currently because it cancels out with the other units we're using. The other variation of the constant will probably be relevant in other contexts
by Nina_A_Section1E
Thu Apr 26, 2018 2:29 pm
Forum: Properties of Light
Topic: Equations for light [ENDORSED]
Replies: 4
Views: 114

Re: Equations for light [ENDORSED]

Yes! Depending on what information is given, and on what you're trying to solve, you use different variations of the equations to get the answer. Sometimes you need to solve one equation to get a value so you can use a different equation - the equations serve as different pathways to the answer!
by Nina_A_Section1E
Fri Apr 20, 2018 1:26 pm
Forum: Properties of Light
Topic: Memorizing Wavelengths [ENDORSED]
Replies: 4
Views: 150

Re: Memorizing Wavelengths [ENDORSED]

I asked my TA, and they said we should know that visible light comes from 400 nm (red) to 700 nm (violet), and know what comes right before and right after (infrared is around 10^-4 to 10^-6 and X-rays are around 10^-8 to 10^-10)
by Nina_A_Section1E
Fri Apr 20, 2018 1:23 pm
Forum: Photoelectric Effect
Topic: Energy levels
Replies: 7
Views: 180

Re: Energy levels

As the energy levels increase, the distance between them decreases, so dropping from energy level 2 to 1 is falling the biggest distance, and therefore emitting the most energy. If an e- drops from energy level 3 to 2, and then 2 to 1, at separate points in time, it will emit 2 photos, but the sum o...
by Nina_A_Section1E
Fri Apr 20, 2018 1:19 pm
Forum: Photoelectric Effect
Topic: Wave properties of electrons
Replies: 2
Views: 62

Re: Wave properties of electrons

This site has super helpful pictures! https://study.com/academy/lesson/constructive-and-destructive-interference.html Basically, if the peaks and troughs of 2 waves happen at the same time, it'll create larger peaks and larger troughs because the energies combine. However, if the peak of one wave ha...
by Nina_A_Section1E
Thu Apr 12, 2018 6:50 pm
Forum: SI Units, Unit Conversions
Topic: Clarification on unit conversions
Replies: 4
Views: 128

Re: Clarification on unit conversions

Yes! That's also the same thing is dividing by 10^-9 for nm or 10^-12 for picometers, if that is easier to visualize for dimensional analysis
by Nina_A_Section1E
Thu Apr 12, 2018 6:49 pm
Forum: Molarity, Solutions, Dilutions
Topic: Finding the molarity concentration of one type of atom from a molecule
Replies: 3
Views: 101

Re: Finding the molarity concentration of one type of atom from a molecule

If you're asked to find the concentration of Na ions when there's a solution of a molecule ex. NaCl, you just use the molar ratios to find the concentration! In this example, the ratio of Na+ ions to NaCl is 1:1, so if the NaCl solutions is 0.2 M, then the concentration of Na+ ions is 0.2 once the s...
by Nina_A_Section1E
Thu Apr 12, 2018 1:49 pm
Forum: Photoelectric Effect
Topic: Original Photoelectric Experiment
Replies: 3
Views: 87

Original Photoelectric Experiment

What was the photoelectric experiment originally designed to do? I didn't catch this from the lecture or module video, and I'm not really sure A. Measure how much energy is required to remove an electron from a metal surface. B. Measure how much energy is required to add an electron to a metal surfa...
by Nina_A_Section1E
Fri Apr 06, 2018 1:34 pm
Forum: SI Units, Unit Conversions
Topic: Using units in calculations [ENDORSED]
Replies: 4
Views: 128

Re: Using units in calculations [ENDORSED]

To make it clear where you're getting your numbers from, it could be helpful to include units, but as long as it's clear without them what you're doing, and you get the right answer and give it with the correct units, I bet it'll be okay!
by Nina_A_Section1E
Fri Apr 06, 2018 1:33 pm
Forum: Empirical & Molecular Formulas
Topic: Which mass of Hydrogen should I use?
Replies: 3
Views: 127

Re: Which mass of Hydrogen should I use?

To be safe, you can use the more specific mass - I always just use 1.008 which is the value most periodic tables have, and uses the same number of sig figs that are other atomic masses are given in (ex. 12.011 for C, 15.999 for O) In the modules, the atomic mass has been given a lot of the time, so ...
by Nina_A_Section1E
Fri Apr 06, 2018 1:30 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Dimensional Analysis Help [ENDORSED]
Replies: 6
Views: 244

Re: Dimensional Analysis Help [ENDORSED]

Use dimensional analysis when you have a quantity in terms of one type of units, but you need to convert it to another type of units. Some people like to do this 1. step by step, ex. converting g to mol, then a separate equation for mols to atoms, etc. 2. Others like to do this all in 1 step, like b...

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