Search found 31 matches

by Isobel Tweedt 1E
Sun Jun 10, 2018 10:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Helpful Chart
Replies: 18
Views: 462

Re: Helpful Chart

Just to be clear, they are less than because the loan electron pair pushes the other atoms farther away from it (and thus closer to other atoms). This then results in increasingly smaller angles between atoms as you move left to right along the chart.
by Isobel Tweedt 1E
Sun Jun 10, 2018 10:14 pm
Forum: Bronsted Acids & Bases
Topic: Oxoacids
Replies: 4
Views: 194

Re: Oxoacids

When using a strong acid our chemical equation can use a single arrow to show the reaction correct? This is because it is donating essentially all H+ protons?
by Isobel Tweedt 1E
Sun Jun 10, 2018 10:12 pm
Forum: Lewis Acids & Bases
Topic: Donating electrons
Replies: 3
Views: 210

Re: Donating electrons

It's also important to remember that while acids always donate protons, Lewis acids accept pairs of electrons from Lewis base. Thus remember that acids donate protons but they can also accept thing (i.e. electron pairs).
by Isobel Tweedt 1E
Sun Jun 03, 2018 10:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Hybridization and Molecular Shape
Replies: 1
Views: 36

Hybridization and Molecular Shape

When determining hybridization is it always reliable to draw the lewis structure, determine the molecular shape, and then find the hybridization formula? What is the relationship between molecular shape and hybridization?
by Isobel Tweedt 1E
Sun Jun 03, 2018 10:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs
Replies: 7
Views: 185

Re: Lone pairs

In the case of linear shapes when a trigonal bipyramidal has 3 loan pairs or an octahedral has 4 loan pairs the bond angles are determined to be 180 degrees. How do loan pairs cause this?
by Isobel Tweedt 1E
Sun Jun 03, 2018 10:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Pi bonds
Replies: 4
Views: 120

Re: Pi bonds

When determining pi bonds in double and triple bonds does it matter which bond is "selected" as the pi and sigma bonds?
by Isobel Tweedt 1E
Sun May 27, 2018 8:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Types of Bonds
Replies: 6
Views: 161

Re: Types of Bonds

I was confused by this too, so here's a helpful website with images of what the bonds look like to demonstrate the different overlapping properties: https://sites.google.com/site/ed350201003/Task
by Isobel Tweedt 1E
Sun May 27, 2018 8:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance
Replies: 7
Views: 238

Re: Resonance

Also remember to address how bond strength is affected by resonance structures. For instance a double bond in a resonance structure is shorter (and thus stronger) than a regular double bond. This is because the actual structure is a combination of the resonance structures (and thus bonds).
by Isobel Tweedt 1E
Sun May 27, 2018 8:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle
Replies: 10
Views: 234

Re: Bond Angle

As a follow up, how do lone pairs affect bond angles? I understand that the lone pair sits more on top of the central atom - but does this always have the same affect on the angles?
by Isobel Tweedt 1E
Sun May 20, 2018 10:39 pm
Forum: Ionic & Covalent Bonds
Topic: Polarization
Replies: 7
Views: 258

Re: Polarization

I'm still confused too, but it helps to see how covalently bonded atoms can become ionicly bonded cations or anions. Here's a helpful website:

https://www.diffen.com/difference/Coval ... onic_Bonds
by Isobel Tweedt 1E
Sun May 20, 2018 10:31 pm
Forum: Electronegativity
Topic: Electronegativity vs. Electron affinity
Replies: 7
Views: 264

Re: Electronegativity vs. Electron affinity

This also means that electronegativity and electron affinity follow the same periodic trends - increasing as you move up and to the right. This also means the atomic size is decreasing.
by Isobel Tweedt 1E
Sun May 20, 2018 10:28 pm
Forum: Octet Exceptions
Topic: Radicals [ENDORSED]
Replies: 6
Views: 342

Re: Radicals [ENDORSED]

Are there any elements that cannot only have one electron attached? Or are there any that are more likely to have just one in a lewis structure?
by Isobel Tweedt 1E
Sun May 13, 2018 10:22 pm
Forum: Ionic & Covalent Bonds
Topic: VALENCE ELECTRONS [ENDORSED]
Replies: 16
Views: 444

Re: VALENCE ELECTRONS [ENDORSED]

How do valence electrons influence Lewis structures? Are they represented in any particular way?
by Isobel Tweedt 1E
Sun May 13, 2018 10:17 pm
Forum: Ionic & Covalent Bonds
Topic: cation vs anion
Replies: 14
Views: 426

Re: cation vs anion

It helps to think of these in terms of a cation makes the ion "more positive" by removing electrons. Becuase an electron is negatively charged, removing it will make the element more positive. Correspondingly, an anion makes an element more negative by adding more electrons.
by Isobel Tweedt 1E
Sun May 13, 2018 10:13 pm
Forum: Ionic & Covalent Bonds
Topic: VALENCE ELECTRONS [ENDORSED]
Replies: 16
Views: 444

Re: VALENCE ELECTRONS [ENDORSED]

Look at the group of the periodic table that the element is in. For example, Carbon is in group 4 and has 4 valence electrons.
by Isobel Tweedt 1E
Sat May 05, 2018 12:46 pm
Forum: Photoelectric Effect
Topic: Frequency on Photoelectric Effect
Replies: 5
Views: 208

Re: Frequency on Photoelectric Effect

If you do have a high enough frequency (which in turn decreases the wavelength) then increasing the intensity will result in the release of more electrons. This is because more photons are hitting the metal and thus able to eject more electrons. As it says in the post above 10 photons that meet the ...
by Isobel Tweedt 1E
Sat May 05, 2018 12:41 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: energy with s,p,d,f
Replies: 3
Views: 108

Re: energy with s,p,d,f

I'm not sure I understand your whole question but here's some help on how to read the periodic table. If you look at the s-block there are only two columns, thus you can have 2s^1 2s^2 to get to Beryllium. So the 2 comes from row 2 and the ^1 and ^2 are the electrons (see columns). Similarly, in the...
by Isobel Tweedt 1E
Sat May 05, 2018 12:33 pm
Forum: Molarity, Solutions, Dilutions
Topic: dilution
Replies: 4
Views: 228

Re: dilution

Another note on this topic - I asked my TA what happens when you remove a solute and if that changes the volume. She said that typically the change in volume would be so small we're not expected to calculate the density and correspodning change in volume. However, this calculation density = (mass)/(...
by Isobel Tweedt 1E
Sat Apr 28, 2018 3:04 pm
Forum: DeBroglie Equation
Topic: Wavelength= (h/p) [ENDORSED]
Replies: 7
Views: 336

Re: Wavelength= (h/p) [ENDORSED]

Just to clarify the De Broglie equation does not work for objects without a rest mass (such as light). If you think about how light always has a constant speed it will never stop and thus never have a resting mass.
by Isobel Tweedt 1E
Sat Apr 28, 2018 3:03 pm
Forum: Properties of Electrons
Topic: Mass of an Electron [ENDORSED]
Replies: 4
Views: 228

Re: Mass of an Electron [ENDORSED]

Specifically, we know that the mass of an electron is 9.1095 x 10^-31 kg and the charge is 1.602 X 10^-19 coulombs. You can also find this on your formula sheet.
by Isobel Tweedt 1E
Sat Apr 28, 2018 3:00 pm
Forum: Properties of Light
Topic: Equations for light [ENDORSED]
Replies: 4
Views: 131

Re: Equations for light [ENDORSED]

Another important thing to note is that light always has the same constant speed (2.99792 x 10^8 m/s). This means any question about what speed light is traveling is actually really easy! Plus we should remember that light has no rest mass and thus cannot be used with the De Broglie equation. It's e...
by Isobel Tweedt 1E
Mon Apr 16, 2018 9:26 pm
Forum: Properties of Light
Topic: Calculating wavelength [ENDORSED]
Replies: 4
Views: 89

Re: Calculating wavelength [ENDORSED]

Is there ever a time we would look for a speed other than that of light? Or does this equation only ever use c?
by Isobel Tweedt 1E
Mon Apr 16, 2018 9:23 pm
Forum: Properties of Light
Topic: Calculating wavelength [ENDORSED]
Replies: 4
Views: 89

Re: Calculating wavelength [ENDORSED]

The basic equation c = fλ can be arranged as you would rearrange an equation in math. By moving around the variables you are keeping the equation the same, but making it easier to select for the unknown value you are trying to find. For instance, if I want to find the frequency of a wave I would use...
by Isobel Tweedt 1E
Mon Apr 16, 2018 9:17 pm
Forum: Properties of Light
Topic: Wavelength [ENDORSED]
Replies: 9
Views: 296

Re: Wavelength [ENDORSED]

Here's a helpful example of measuring a wavelength without using the peak to peak method. If you scroll down there's a great diagram in which the wavelength is measured from a different position on the wave!

https://tests.capnhq.gov/ops/archer_tra ... iation.cfm
by Isobel Tweedt 1E
Mon Apr 16, 2018 2:08 pm
Forum: Photoelectric Effect
Topic: Threshold Energy [ENDORSED]
Replies: 12
Views: 340

Re: Threshold Energy [ENDORSED]

How does this relate to the concept of darkness versus lightness? Does the release of electrons result in our viewing of light and the color spectrum?
by Isobel Tweedt 1E
Mon Apr 16, 2018 2:06 pm
Forum: Einstein Equation
Topic: Combining E=hv and c=ƛv [ENDORSED]
Replies: 7
Views: 262

Re: Combining E=hv and c=ƛv [ENDORSED]

v = c/ƛ so E = hc/ƛ
by Isobel Tweedt 1E
Mon Apr 16, 2018 2:04 pm
Forum: Properties of Light
Topic: Amplitude
Replies: 3
Views: 69

Re: Amplitude

To clarify, you square the amplitude to get the intensity of that wave.
by Isobel Tweedt 1E
Mon Apr 09, 2018 4:55 pm
Forum: Significant Figures
Topic: 300 vs 300. [ENDORSED]
Replies: 8
Views: 519

Re: 300 vs 300. [ENDORSED]

1. non zero = significant digit 1.234 has 4 2. zeros between two significant digits = significant digit 1.002 has 4 3. leading zeros = not significant digits 0.003 has 1 4. zeros following significant digits and a decimal = significant digits 300.0 has 4 0.0030 has 2 5. trailing zeros to the right o...
by Isobel Tweedt 1E
Mon Apr 09, 2018 4:49 pm
Forum: Molarity, Solutions, Dilutions
Topic: Module Assessment Question
Replies: 3
Views: 120

Re: Module Assessment Question

Also just a note on working with molarity and liquids: when working with liquids the total solution volume changes (make sure to pay attention to the units your liquid is measured in). In this problem we are dealing with a 250ml flask and a solid solute (as seen with units grams) so the total volume...
by Isobel Tweedt 1E
Mon Apr 09, 2018 4:46 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar Mass
Replies: 9
Views: 401

Re: Molar Mass

Can someone please clarify when we use molar mass versus atomic mass?
by Isobel Tweedt 1E
Mon Apr 09, 2018 4:36 pm
Forum: Limiting Reactant Calculations
Topic: Avogadro's Number
Replies: 1
Views: 84

Avogadro's Number

When do I need to use Avogadro's Number?

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