Search found 30 matches
- Tue Jun 05, 2018 6:10 pm
- Forum: Lewis Acids & Bases
- Topic: 12.13.A Significance of lone pairs in determining Lewis acid/base?
- Replies: 3
- Views: 473
Re: 12.13.A Significance of lone pairs in determining Lewis acid/base?
Lewis acids are lone pair acceptors while bases are donors. This means that if a molecule has a lone pair on the central atom, it will be a lewis base, just like ammonia.
- Tue Jun 05, 2018 6:06 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Trigonal Planar vs Trigonal Pyramidal
- Replies: 5
- Views: 16032
Re: Trigonal Planar vs Trigonal Pyramidal
As people have stated, it has everything to do with lone pairs on the central atom
- Tue Jun 05, 2018 6:03 pm
- Forum: Bronsted Acids & Bases
- Topic: How to identify a Bronsted acid or base
- Replies: 11
- Views: 4433
Re: How to identify a Bronsted acid or base
Bronsted acids donate protons (H+) while bronsted bases accept protons.
- Tue May 29, 2018 7:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework 4.7
- Replies: 3
- Views: 461
Re: Homework 4.7
Since it's trigonal pyramidal, I think you're right that the angles are all the same.
- Tue May 29, 2018 7:42 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Form vs. Shape
- Replies: 2
- Views: 333
Re: Form vs. Shape
I believe form refers to all the electron regions around the central atom (including lone pairs), while shape does not account for the lone pair regions. In the case of water, there are 4 electron regions which would create a tetrahedral form, but since we don't count lone pairs in shape it's just b...
- Mon May 28, 2018 2:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSPER MODEL
- Replies: 3
- Views: 1325
Re: VSPER MODEL
I'm pretty sure Lavelle mentioned resonance structures don't affect VSEPR models, but lone pairs do.
- Sun May 20, 2018 11:29 pm
- Forum: Lewis Structures
- Topic: central atom
- Replies: 7
- Views: 613
Re: central atom
It's generally the least electronegative element that's in the middle.
- Sun May 20, 2018 11:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Stable Lewis structures
- Replies: 4
- Views: 604
Re: Stable Lewis structures
You basically want the structure with the least amount of charge which is found by calculating each element's formal charge. Ideally, there should be a formal charge of 0 for each element present.
- Sun May 20, 2018 11:25 pm
- Forum: Ionic & Covalent Bonds
- Topic: Test 3
- Replies: 2
- Views: 389
Re: Test 3
The website says test 3 covers chapter 3 material so I think it'd be useful to review what we've gone over in lecture.
- Tue May 15, 2018 9:22 am
- Forum: Trends in The Periodic Table
- Topic: 2.6B
- Replies: 2
- Views: 448
Re: 2.6B
Beryllium has 4 electrons which means that if we remove 3, we will be in the 1s shell (the core). On the other hand, when we remove 3 electrons from Boron (has 5 electrons), we only remove the valence electrons (the 2s and 2p). As stated, it is way harder to remove these innermost electrons than it ...
- Tue May 15, 2018 9:18 am
- Forum: Lewis Structures
- Topic: Identifying elements in Lewis structures [ENDORSED]
- Replies: 2
- Views: 735
Re: Identifying elements in Lewis structures [ENDORSED]
It specifically says "period 3 element" which is Na through Ar, and nitrogen is a period 2 element. On top of this, the central atom does not strictly follow the octet rule which is also an indication that it would not be nitrogen.
- Tue May 15, 2018 9:14 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge terms
- Replies: 2
- Views: 462
Re: Formal Charge terms
I like to do the following formula to calculate it:
formal charge = valence electrons of the atom - (lone pairs + .5* bonded electrons).
formal charge = valence electrons of the atom - (lone pairs + .5* bonded electrons).
- Sat May 05, 2018 8:21 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configurations Exceptions
- Replies: 3
- Views: 406
Re: Electron Configurations Exceptions
I think molybdenum is part of this list as well, and you just need to remember that those elements will take an e- from the s shell to fill the d shells (singly for Mo and Cr, and doubly for Cu and Ag).
- Sat May 05, 2018 7:02 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Exceptions for electron configuration
- Replies: 3
- Views: 473
Re: Exceptions for electron configuration
In period 4, Chromium and Copper fill their shells differently than you'd expect. Instead of Chromium having the electron configuration [Ar] 3d 4 4s 2 , it's actually more stable with the following configuration [Ar] 3d 5 4s 1 . Likewise, Copper is expected to be [Ar] 3d 9 4s 2 but it fills the d sh...
- Sat May 05, 2018 6:55 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: D and S oribitals
- Replies: 3
- Views: 405
Re: D and S oribitals
If you're asking about writing them out, it's a personal preference I believe. For example, some people would write scandium as [Ar] 4s2 3d1 but others write it as [Ar] 3d1 4s2
- Tue May 01, 2018 7:02 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: question on a problem
- Replies: 1
- Views: 307
Re: question on a problem
Yup! Since only one electron can have that positive spin number, the answer is 1.
- Mon Apr 30, 2018 7:51 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: cation or anion?
- Replies: 4
- Views: 590
Re: cation or anion?
If it gains electrons, it will be negatively charged which is an anion. If it loses electrons, it will be positively charged which is a cation.
- Mon Apr 30, 2018 7:45 pm
- Forum: *Shrodinger Equation
- Topic: How are orbitals corresponding to m sub l numbers
- Replies: 2
- Views: 482
Re: How are orbitals corresponding to m sub l numbers
If you're referring to m, it corresponds to the magnetic quantum number which tells us the number of orbitals and their orientation, if i'm not mistaken.
- Sat Apr 28, 2018 11:53 pm
- Forum: Properties of Electrons
- Topic: Hydrogen Levels and Energy [ENDORSED]
- Replies: 3
- Views: 543
Re: Hydrogen Levels and Energy [ENDORSED]
As others have said, higher values of n mean higher energies. If you go from n=1 to n=5, you need more energy to do so than if you went from n=1 to n=2. This also means that more energy is released when the electron returns to the ground state from a higher energy level.
- Sat Apr 28, 2018 11:39 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Coefficients in electron configurations [ENDORSED]
- Replies: 4
- Views: 3886
Re: Coefficients in electron configurations [ENDORSED]
As stated, the coefficient represents the corresponding period of the specific element.
- Sat Apr 28, 2018 11:32 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Hund's Rule [ENDORSED]
- Replies: 6
- Views: 1164
Re: Hund's Rule [ENDORSED]
Hund's rule is just stating that electrons cannot have paired spins until the other orbitals are all filled first.
- Wed Apr 25, 2018 7:30 am
- Forum: Photoelectric Effect
- Topic: Frequency on Photoelectric Effect
- Replies: 5
- Views: 656
Re: Frequency on Photoelectric Effect
The number of electrons ejected has to do with the intensity. The photoelectric effect only takes one electron into account without the intensity in mind, I believe.
- Wed Apr 25, 2018 7:28 am
- Forum: Einstein Equation
- Topic: Energy Absorbed in a Mole? - HW Problem #55
- Replies: 1
- Views: 302
Re: Energy Absorbed in a Mole? - HW Problem #55
Since you found the energy per photon, to find the energy of a mol of photons all you'd have to do is multiply by avogadro's number which is 6.022 x10^23
- Wed Apr 25, 2018 7:26 am
- Forum: Photoelectric Effect
- Topic: calculating the number of photons
- Replies: 2
- Views: 413
Re: calculating the number of photons
Divide the total number of Joules emitted by the amount of energy per photon!
- Mon Apr 16, 2018 11:11 pm
- Forum: Limiting Reactant Calculations
- Topic: moles + limiting reactant
- Replies: 2
- Views: 458
Re: moles + limiting reactant
You can always plug the values of the reactants, one at a time, into the equation and whichever yields less product will be the limiting reactant.
- Mon Apr 16, 2018 11:09 pm
- Forum: Properties of Light
- Topic: HW 1.15
- Replies: 4
- Views: 403
Re: HW 1.15
Because the wavelength 102.6 nm corresponds to the lyman series, we know that the energy level, n1, will be at the ground state (n=1).
- Mon Apr 16, 2018 11:02 pm
- Forum: Properties of Light
- Topic: 1.13 (b)
- Replies: 6
- Views: 714
Re: 1.13 (b)
As others have said, your answer should be written in terms of nanometers. I got .486 x 10^-6 which translates to 486 x 10^-9 (486 nanometers). This wavelength corresponds to the balmer series, but more specifically, blue visible light.
- Mon Apr 16, 2018 10:56 pm
- Forum: Properties of Light
- Topic: The speed of light
- Replies: 4
- Views: 455
Re: The speed of light
In a vacuum, yes. The only thing that's different is their frequencies & wavelengths I believe.
- Wed Apr 11, 2018 10:43 am
- Forum: Limiting Reactant Calculations
- Topic: Mass of Products VS. Mass of Reactants- Class Assessment
- Replies: 5
- Views: 3167
Re: Mass of Products VS. Mass of Reactants- Class Assessment
Like everyone else is saying, chemistry strictly follows the law of conservation of mass. What we would ideally observe is the same masses, but sometimes mass is lost when we transfer the products elsewhere.
- Wed Apr 11, 2018 10:37 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Ionic Concentrations
- Replies: 1
- Views: 284
Ionic Concentrations
How exactly do you find ionic concentrations when salts are dissolved in water?