Search found 30 matches

by Fiona Grant 1I
Fri Jun 08, 2018 3:48 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxalate Bidentate?
Replies: 1
Views: 64

Oxalate Bidentate?

Why is oxalate bidentate? Aren't there four oxygens with lone pairs, meaning there are four potential binding sites, thus making it tetradentate?
by Fiona Grant 1I
Fri Jun 08, 2018 3:38 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 5
Views: 213

Re: Polydentate

How exactly would you be able to identify where it can form a bond, in order to determine if it is polydentate? For example, how do you know that the molecule N(CH2CH2NH2)2 is tetradentate.
by Fiona Grant 1I
Fri Jun 08, 2018 3:13 pm
Forum: Bronsted Acids & Bases
Topic: J.1
Replies: 1
Views: 149

J.1

Identify each compound as either a Brønsted acid or a Brønsted base: (a) NH3; (b) HBr; (c) KOH; (d) H2SO3; (e) Ca(OH)2.

For part (a), I'm having some trouble understanding why NH3 is a Brønsted base. I thought it would be an acid because of the hydrogens present in the molecule?
by Fiona Grant 1I
Fri Jun 01, 2018 3:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair Placement [ENDORSED]
Replies: 2
Views: 82

Lone Pair Placement [ENDORSED]

I remember that we learned about how for some molecular shapes, it doesn't matter where you choose to place the lone pair, whereas for others, it does. For example, I believe that in molecules with a tetrahedral shape, the placement of the lone pair doesn't matter, but in molecules with trigonal bip...
by Fiona Grant 1I
Fri Jun 01, 2018 3:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How is this linear?
Replies: 2
Views: 92

Re: How is this linear?

You have to imagine it in a three-dimensional perspective, rather than how it looks in a Lewis structure. In a trigonal bipyramidal 3D shape, there are 3 atoms in a trigonal planar arrangement, 1 atom on top, and the other atom below. In this molecule, which has 3 lone pairs, these lone pairs are in...
by Fiona Grant 1I
Fri Jun 01, 2018 2:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis Structure for VSEPR
Replies: 2
Views: 83

Lewis Structure for VSEPR

I noticed in the solution manual that many of the Lewis structures are not the most stable structure. I know that this does not make a difference when it comes to making the VSEPR formula, but I had been drawing the most stable ones out of habit. Does this not matter as much in this unit? As in, wou...
by Fiona Grant 1I
Fri May 25, 2018 3:51 pm
Forum: Sigma & Pi Bonds
Topic: Covalent or Ionic?
Replies: 1
Views: 146

Covalent or Ionic?

I was wondering how sigma and pi bonds fit in with covalent and ionic bonding? Do they only occur in one or the other, or can they be present in any type of bond?
by Fiona Grant 1I
Fri May 25, 2018 3:46 pm
Forum: Lewis Structures
Topic: Why Resonance for SO2?
Replies: 3
Views: 320

Re: Why Resonance for SO2?

You are correct that the structure with 2 double bonds is the most stable structure. However, since the question specifically asks for three resonance structures, you should also include the two resonance structures that have 1 single bond and 1 double bond between the S and each O, even though they...
by Fiona Grant 1I
Fri May 25, 2018 3:37 pm
Forum: Bond Lengths & Energies
Topic: 3.87
Replies: 5
Views: 216

Re: 3.87

I'm confused about this. I thought that it would be Br, because Br is the largest atom? If the centers of the F and Br atoms are in the same place in both cases, since the F atom is smaller, there would be a greater distance between the C and F, and F would be the longer and weaker bond. Whereas wit...
by Fiona Grant 1I
Fri May 18, 2018 4:00 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Covalent Character
Replies: 3
Views: 123

Re: Covalent Character

Ok, that clears it up, thank you!

Just a follow-up question: what is the general trend for increasing covalent character of an ionic bond? (In other words, what in the bond changes in order for covalent character to increase?)
by Fiona Grant 1I
Fri May 18, 2018 3:59 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Covalent Character
Replies: 3
Views: 123

Covalent Character

In class, we talked a bunch about how ionic bonds have covalent character. What exactly does it mean for a bond to have "covalent character"? There was something about "highly distorted electrons" and "highly polarizable" but I'm having some trouble understanding this.
by Fiona Grant 1I
Fri May 18, 2018 3:28 pm
Forum: Resonance Structures
Topic: 3.45
Replies: 1
Views: 116

3.45

Draw the Lewis structures that contribute to the resonance hybrid of nitryl chloride, ClNO2 (N is the central atom). I know that for the Lewis structure, there are two single bonds and one double bond. The answer key shows that the 2 possible resonance structures have the double bond between N and e...
by Fiona Grant 1I
Sun May 13, 2018 1:48 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy vs. Electron Affinity
Replies: 4
Views: 168

Ionization Energy vs. Electron Affinity

I was wondering what the difference is between ionization energy and electron affinity? It seemed somewhat like we were using the two terms interchangeably in class, but I wasn't sure if this is actually correct. Do they have the same periodic trends?
by Fiona Grant 1I
Sun May 13, 2018 1:39 pm
Forum: Trends in The Periodic Table
Topic: Second Ionization
Replies: 3
Views: 175

Re: Second Ionization

The 2nd ionization energy is higher because it is more difficult to remove the second electron from the atom. When you remove the first electron, the atom becomes more positively charged, so the remaining electrons are pulled into the nucleus more strongly. As a result, more energy is required to re...
by Fiona Grant 1I
Sun May 13, 2018 1:38 pm
Forum: Lewis Structures
Topic: KCl Lewis formula
Replies: 6
Views: 481

KCl Lewis formula

In one of the first lectures of this unit, we did an example of the Lewis formula of KCl. In this example, Cl ended up with all of the electrons in the final Lewis structure. I was just wondering why this was the case? How often would we have to do this type of Lewis structure rather than what we ha...
by Fiona Grant 1I
Sat May 05, 2018 3:06 pm
Forum: Trends in The Periodic Table
Topic: Practice midterm 6d
Replies: 2
Views: 74

Practice midterm 6d

The question asks us to rank C,N,O, and F in order of increasing ionization energies. I know that the solution is C < O < N < F, however I expected the answer to be C < N < O < F because the ionization energy increases across a period. We talked about how this is an exception during the review sessi...
by Fiona Grant 1I
Sat May 05, 2018 2:48 pm
Forum: Trends in The Periodic Table
Topic: Ionic radius trend
Replies: 2
Views: 85

Ionic radius trend

I understand the basic idea that ionic radii shows the same trends as atomic radii (radius increases down a group and decreases across a period), but I am confused as to how cations are smaller than the parent atom, and anions are larger. Wouldn't this contradict the atomic radii trend?
by Fiona Grant 1I
Sat May 05, 2018 2:35 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Anion electron configuration
Replies: 2
Views: 129

Anion electron configuration

In lecture, we were told that the rule for electron configurations of anions is to add electrons until the next noble gas configuration. I'm kind of confused about how this was explained, because it seemed it seemed like it was different from the cation electron configuration rule. Are we always goi...
by Fiona Grant 1I
Thu Apr 26, 2018 11:56 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: HW #1.43
Replies: 8
Views: 421

HW #1.43

What is the minimum uncertainty in the speed of an electron confined to within a lead atom of diameter 350. pm?

When I calculated the answer to this problem, I got an answer of 1.51 x 10^-25 m/s. However, apparently the solution should be 1.65 x 10^5 m/s. How am I getting a value that is so off?
by Fiona Grant 1I
Thu Apr 26, 2018 11:32 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes [ENDORSED]
Replies: 6
Views: 186

Nodal Planes [ENDORSED]

What exactly is the formal definition of a nodal plane? I understand what they are in the context of looking at an image of an orbital, but I would just like to know what their significance is.
by Fiona Grant 1I
Thu Apr 26, 2018 11:18 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Indeterminacy of Momentum
Replies: 2
Views: 86

Re: Indeterminacy of Momentum

I think that you will always have to calculate the indeterminacy in velocity using delta p = (mass) x (delta v). Momentum includes both mass and velocity in the value, so it is difficult to infer anything useful from just the indeterminacy in momentum. This is why we took the extra step and found th...
by Fiona Grant 1I
Sat Apr 21, 2018 8:10 pm
Forum: DeBroglie Equation
Topic: equations that apply to light only/everything else but light
Replies: 8
Views: 274

Re: equations that apply to light only/everything else but light

I don't think that light has momentum (p), because p = mv, and while light has velocity, it does not have mass. So the equation would not apply in this case. I am not sure though.
by Fiona Grant 1I
Sat Apr 21, 2018 7:50 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation [ENDORSED]
Replies: 3
Views: 167

Rydberg Equation [ENDORSED]

I remember that in class, we did example where we found the frequency of light being emitted when an electron changes energy levels. In this example, we used the equation E = -hR/n^2 at each energy level and then subtracted them to find the frequency using E = hv. I understand how the Rydberg equati...
by Fiona Grant 1I
Sat Apr 21, 2018 7:16 pm
Forum: Einstein Equation
Topic: Planck's Constant Value [ENDORSED]
Replies: 7
Views: 2756

Planck's Constant Value [ENDORSED]

When we are doing calculations involving Planck's constant, h, I was just wondering if it is better to use 6.626 x 10^-34 J.s or 6.63 x 10^-34 J.s? I've seen it both ways and I was just curious. Thanks!
by Fiona Grant 1I
Sun Apr 15, 2018 3:51 pm
Forum: Photoelectric Effect
Topic: Practice Problem [ENDORSED]
Replies: 1
Views: 49

Practice Problem [ENDORSED]

Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 10^5 m/s. The work function for sodium is 150.6 kJ/mol. A. What is the kinetic energy of the ejected electron? For this problem, I want to use the equation E(k)=(1/2)(m(e-))(v(e-)^2) to find kinetic energy. The velo...
by Fiona Grant 1I
Sun Apr 15, 2018 3:41 pm
Forum: Photoelectric Effect
Topic: Threshold Energy Definition
Replies: 3
Views: 323

Re: Threshold Energy Definition

Threshold energy is the amount of energy per photon that is required to eject electrons from a metal surface.

This is the same thing as the work function, and is represented by the symbol Φ.
by Fiona Grant 1I
Sun Apr 15, 2018 2:55 pm
Forum: Limiting Reactant Calculations
Topic: Finding Excess Reactant [ENDORSED]
Replies: 2
Views: 486

Finding Excess Reactant [ENDORSED]

I understand how to find the amount of product formed from a limiting reactant. But how exactly do you calculate the mass of the excess reactant that is leftover once this reaction takes place?
by Fiona Grant 1I
Sun Apr 08, 2018 2:15 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding molar ratios
Replies: 3
Views: 741

Rounding molar ratios

When finding the ratio of moles in order to determine an empirical formula, what are the rules for rounding? For example, if i were to divide by the smallest number while calculating the ratios and one of my results is 15.80, how do I know if I can round this up to the nearest whole number, or if I ...
by Fiona Grant 1I
Sun Apr 08, 2018 1:56 pm
Forum: Empirical & Molecular Formulas
Topic: Order of Elements in Empirical Formula [ENDORSED]
Replies: 4
Views: 742

Re: Order of Elements in Empirical Formula [ENDORSED]

I believe that the general rule is that, if there is carbon present in the compound, the order of elements is carbon first, then hydrogen, the the rest of the elements in alphabetical order. If there is no carbon in the compound, then the elements just go in alphabetical order in the formula. Howeve...
by Fiona Grant 1I
Sun Apr 08, 2018 1:33 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.5 [ENDORSED]
Replies: 1
Views: 140

G.5 [ENDORSED]

I am still a bit confused as to the setup of this problem. How do you find the molarity of the Na2CO3 solution using the mass and volume given? I know that n=m/M and c=n/V, but I don't understand how to find the concentration using these equations.

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