Search found 32 matches

by Megan Wong 4E
Fri Dec 07, 2018 12:38 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH sig figs
Replies: 4
Views: 56

Re: pH sig figs

I went to a review session and the UA said sig figs for pH pertains to numbers after the decimal.

For example, a pH of 5.435 has 3 sig figs.
by Megan Wong 4E
Wed Dec 05, 2018 9:58 am
Forum: Naming
Topic: naming differences
Replies: 6
Views: 78

Re: naming differences

I don't believe your first example would be the same compound, as pentaaquathiocyano would be pentaaquathiocyanido. On Dr. Lavelle's website there is a link to a pdf ("Naming Coordination Compounds") showing a chart with the different names, one being the name (Ex: chloro) and the other be...
by Megan Wong 4E
Wed Dec 05, 2018 9:54 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Determining possible intermolecular forces
Replies: 3
Views: 60

Re: Determining possible intermolecular forces

Aside from VDW, as you mentioned, that can be found in all molecules, another one is that hydrogen bonding can occur between hydrogens attached to either F, O, or N.
by Megan Wong 4E
Tue Nov 27, 2018 8:27 pm
Forum: Hybridization
Topic: Hybridization of Central Atom
Replies: 3
Views: 51

Re: Hybridization of Central Atom

Just to reiterate what has been said previously, the 2 (coefficient in front of sp) in 2sp^2 is basically like the n quantum number that states the energy level such as in 2s or 2p.

2sp shows that the s and p orbitals from n=2 have been hybridized.
by Megan Wong 4E
Tue Nov 27, 2018 2:32 am
Forum: Electronegativity
Topic: Electronegativity
Replies: 4
Views: 96

Re: Electronegativity

I'm thinking that electronegativity on the test may be applied based on periodic trends if it regards C, N, O, F, and Cl since those are the most electronegative elements (top right of periodic table).
by Megan Wong 4E
Tue Nov 27, 2018 1:29 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw or Square Planar
Replies: 3
Views: 64

Seesaw or Square Planar

How can you differentiate whether the molecular structure of a compound is supposed to be seesaw or square planar for VSEPR models?
by Megan Wong 4E
Sat Nov 24, 2018 2:15 pm
Forum: Electronegativity
Topic: Arrows showing charge
Replies: 4
Views: 103

Re: Arrows showing charge

The arrows point towards the element that has the slightly negative charge, or where the electrons have a higher density.
For example, in HCl, H is slightly positive while Cl is slightly negative, so the arrow points towards Cl.
by Megan Wong 4E
Fri Nov 23, 2018 12:11 am
Forum: Dipole Moments
Topic: Nodal Planes
Replies: 2
Views: 65

Re: Nodal Planes

Nodal planes are areas where there is no possibility of electron density. In other words, it will be impossible to find electrons in nodal planes.
Essentially for this class, I believe that all you need to know is that the p orbital has 1 nodal plane and the d orbital has 2 nodal planes.
by Megan Wong 4E
Tue Nov 20, 2018 12:10 am
Forum: SI Units, Unit Conversions
Topic: Significant 0’s
Replies: 4
Views: 136

Re: Significant 0’s

Zeroes between 2 nonzero numbers are significant
Ex) 202 has 3 sig figs
Final zeroes or trailing zeroes in the decimal portion are also significant.
Ex) 0.0850 only has 3 significant digits.
by Megan Wong 4E
Sun Nov 18, 2018 7:58 pm
Forum: Dipole Moments
Topic: Difference between dipole and london forces?
Replies: 5
Views: 84

Re: Difference between dipole and london forces?

In addition, London forces, also known as Van der Waal's forces, cause a temporary partial charge for the atoms involved and is very weak.
by Megan Wong 4E
Wed Nov 14, 2018 8:18 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 4
Views: 60

Re: Polarizability

Yes, polarizability only pertains to anions. By definition, polarizability is how easily it is for the atom to have distorted electron clouds.

Cations on the other hand have polarizing power, which is the ability to distort the electron clouds of anions.
by Megan Wong 4E
Tue Nov 13, 2018 1:54 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 3
Views: 98

Re: Formal Charge

I think that formal charge is more important than the octet rule in order to find the most stable Lewis dot structure. After creating bonds and applying the left over lone pairs to reach the appropriate number of electrons, the formal charge should override the octet rule. Elements that can have exp...
by Megan Wong 4E
Wed Nov 07, 2018 5:12 pm
Forum: Trends in The Periodic Table
Topic: Noble Gases
Replies: 1
Views: 120

Re: Noble Gases

I know that noble gases after 3p can have expanded octets in covalent bonds. In homework problem #11 in 2C (7th edition), there are instances where Xenon (a noble gas) would have more than 8 electrons in its Lewis structure. For example, with XeOF4 there are 6 bonds with 1 lone pair making Xe have a...
by Megan Wong 4E
Wed Nov 07, 2018 5:05 pm
Forum: Dipole Moments
Topic: dispersion forces vs. london forces
Replies: 2
Views: 33

Re: dispersion forces vs. london forces

Agreeing with the above response, dispersion forces, London, induced dipole-induced dipole, and Van der Waal interactions all refer to the same thing.
by Megan Wong 4E
Wed Nov 07, 2018 5:02 pm
Forum: Trends in The Periodic Table
Topic: First, second, third, etc. Ionization energy
Replies: 4
Views: 105

Re: First, second, third, etc. Ionization energy

The first ionization energy is the energy required to remove 1 electron from an atom, the second ionization energy is the energy required to removed 2 electrons, and so forth. I believe that ionization energies increase as you remove more electrons. For instance, the second ionization energy will al...
by Megan Wong 4E
Sun Nov 04, 2018 10:59 pm
Forum: Ionic & Covalent Bonds
Topic: Nitrogen or Oxygen as Central Atom
Replies: 2
Views: 45

Nitrogen or Oxygen as Central Atom

When doing Lewis structures, the rule of thumb is to use the atom with the least ionization energy as the central atom. If one exception to the general trend of ionization energy (increases from left to right) is that nitrogen is higher in IE than oxygen, which would be the central atom? For example...
by Megan Wong 4E
Fri Nov 02, 2018 10:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: question 4.b on Test2
Replies: 1
Views: 30

Re: question 4.b on Test2

The correct response would be that the energy levels are discrete/quantized. There are specific values for each energy level.
by Megan Wong 4E
Fri Nov 02, 2018 2:24 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Is electron removed from 3d or 4s first?
Replies: 5
Views: 482

Re: Is electron removed from 3d or 4s first?

Yes, electrons will be lost from the 4s orbital rather than the 3d orbital.

In this example, Mn's configuration is 1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 4s^2
and Mn +1 would be 1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 4s^1.
by Megan Wong 4E
Thu Nov 01, 2018 10:28 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formulas with Masses
Replies: 3
Views: 95

Re: Empirical Formulas with Masses

Prior to doing the steps above, you would have to also find the mass percentage of each element in the compound. Then you can assume, based on the percentages, that the compound is out of 100g.
by Megan Wong 4E
Wed Oct 24, 2018 1:02 am
Forum: Einstein Equation
Topic: Equations for Light Only
Replies: 3
Views: 201

Equations for Light Only

Which equations from this chapter can be used for light only and which (besides the kinetic energy equation) can be used for electrons only?
by Megan Wong 4E
Wed Oct 24, 2018 1:00 am
Forum: Properties of Light
Topic: Electron energy levels??
Replies: 1
Views: 86

Re: Electron energy levels??

Since the electron emits and does not absorb the photon, that means delta E must equal a negative value. So, deltaE = -(-hR/n(final)^2 - -(hR/n(initial)^2). Since E=h(nu), then you can set h(nu) = -(-hR/n(final)^2 - -(hR/n(initial)^2). Once you isolate for n(initial) and complete the math, n will eq...
by Megan Wong 4E
Wed Oct 24, 2018 12:42 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Relationship Between Equations
Replies: 1
Views: 88

Re: Relationship Between Equations

The Rydberg equation finds the change in energy of electrons at a specific energy level. It essentially finds delta E, and the equation utilizes En = -hR/n^2 by finding the change, thus making it deltaE = -hR/n(final)^2) - (-hR/n(initial)^2). Once you simplify the equation, it results to deltaE = hR...
by Megan Wong 4E
Wed Oct 24, 2018 12:35 am
Forum: Photoelectric Effect
Topic: ejecting electrons in quantized energy levels
Replies: 2
Views: 75

Re: ejecting electrons in quantized energy levels

In the photoelectric effect, electrons are excited by incoming light (photons), not by kinetic energy. The energy of the incoming photons must be greater than or equal to the work function. If the incoming energy is greater than the threshold energy, then kinetic energy will be given off as excess e...
by Megan Wong 4E
Sat Oct 20, 2018 8:51 pm
Forum: DeBroglie Equation
Topic: 1B 15 7th edition
Replies: 6
Views: 134

1B 15 7th edition

15. Velocity of electron emitted from a metallic surface by a photon is 3.6 km/s. What is the wavelength of the ejected electron? For this question, I tried to use the kinetic energy formula 1/2mv^2 but it doesn't work out. Why can't I use the KE formula and how do you know it's supposed to be De Br...
by Megan Wong 4E
Wed Oct 17, 2018 6:23 pm
Forum: Properties of Light
Topic: Series
Replies: 4
Views: 75

Re: Series

When reviewing for Test 2, my TA advised that we know the series names for n=1, n=2, n=3, and n=4 for the test (Lyman, Balmer, Paschen, and Brackett respectively).
by Megan Wong 4E
Tue Oct 16, 2018 10:54 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 1.11 Problem
Replies: 3
Views: 41

Re: 1.11 Problem

Would the answer still be correct if I said that they pertain to different parts of the spectrum like how the Balmer series pertains to visible light while the Lyman series regards UV radiation? Or does the answer have to mention the lower energy levels to be right?
by Megan Wong 4E
Fri Oct 12, 2018 8:43 pm
Forum: SI Units, Unit Conversions
Topic: What Unit of Mass to Use?
Replies: 5
Views: 214

Re: What Unit of Mass to Use?

The SI unit for mass, as explained by Lavelle, is kilograms due to the units of Joules which is (kg x m^2 x s^-2). However, usually when doing problems we convert to the base unit which is grams unless an equation states otherwise.
by Megan Wong 4E
Fri Oct 12, 2018 3:24 pm
Forum: Photoelectric Effect
Topic: Variable for frequency
Replies: 6
Views: 62

Re: Variable for frequency

Just to clarify further, v is for velocity while nu is for frequency.
by Megan Wong 4E
Tue Oct 09, 2018 1:58 pm
Forum: Balancing Chemical Reactions
Topic: 7th edition L.35
Replies: 5
Views: 191

Re: 7th edition L.35

I'm also having the same issue with the third equation. In the original problem, the reactants contain FeBr2 but in the solution manual it states that the FeBr2 is actually Fe3Br8, which is then balanced accordingly. How does FeBr2 turn into Fe3Br8?
by Megan Wong 4E
Fri Oct 05, 2018 5:10 pm
Forum: Molarity, Solutions, Dilutions
Topic: Rounding molar mass
Replies: 4
Views: 81

Re: Rounding molar mass

I too would stick to the molar mass given on the periodic table the way it is. The only number I would round is the final answer, and nothing else before.
by Megan Wong 4E
Wed Oct 03, 2018 5:38 pm
Forum: Significant Figures
Topic: Significant Figures
Replies: 3
Views: 52

Re: Significant Figures

We would apply the correct significant figures for the answer only. If every answer from each step taken to reach the solution was rounded, the answer you generate could potentially be too far off from the actual answer. Hope this helps!
by Megan Wong 4E
Wed Oct 03, 2018 1:06 pm
Forum: General Science Questions
Topic: Periodic Table
Replies: 16
Views: 393

Re: Periodic Table

I just had my discussion today, and my TA said to use the exact number on the periodic table that is given. For instance, if the periodic table provided says 12.011 for carbon, use that number rather than just 12.

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