Search found 32 matches

by LilianKhosravi_1H
Mon Jun 11, 2018 10:00 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strength of Acid and Bases
Replies: 3
Views: 142

Re: Strength of Acid and Bases

when something is referred to as "less acidic" it's usually talking about the pH of something rather than the actual strength of the acid but a weak acid would cause little change in pH of a solution or make something acidic. An acid is strong when the pKA is lower and is weaker when the p...
by LilianKhosravi_1H
Sun Jun 10, 2018 7:09 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Sigma vs Pi Bonds
Replies: 4
Views: 171

Re: Sigma vs Pi Bonds

I think it has to do more with the number of bonds. So a single bond is a sigma bond, a double is a sigma and pi bond, and a triple is one sigma and two pi bonds.
by LilianKhosravi_1H
Sun Jun 10, 2018 7:07 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework Problem 17.33.)
Replies: 4
Views: 169

Re: Homework Problem 17.33.)

H2O is a monodentate because even though it has two lone pairs, only one of those will bind and the other one won't because it has no way of biding to the central atom since it's on the oxygen with the other lone pair that is already bound. Basically, the positions of the lone pairs won't allow it t...
by LilianKhosravi_1H
Sun Jun 10, 2018 7:03 pm
Forum: Hybridization
Topic: pi bond and sigma bond
Replies: 3
Views: 107

Re: pi bond and sigma bond

Vivian Gonzalez 1A wrote:What do we need to know about pi and sigma bonds for the final?

I would say know what they each represent and also how many of each make up a single, double, and triple bond.
by LilianKhosravi_1H
Thu Jun 07, 2018 10:23 pm
Forum: Amphoteric Compounds
Topic: Identifying an amphoteric compound
Replies: 3
Views: 260

Re: Identifying an amphoteric compound

what we did in discussion was create an equilibria where we used the amphoteric compound with water and tried to see if we could use it as both an acid and a base. The example we did was H2PO3- : using it as an acid = H2PO3- + H2O ⇌ (HPO3)2- + H3O+ using it as a base = H2PO3- + H2O ⇌ H3PO3 + OH- so,...
by LilianKhosravi_1H
Wed Jun 06, 2018 12:43 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Bonds vs Covalent Bonds
Replies: 7
Views: 109

Re: Ionic Bonds vs Covalent Bonds

I think that's because in Bio we talked about how covalent bonds can't be broken in water but ionic bonds can.
by LilianKhosravi_1H
Sun Jun 03, 2018 5:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Naming Structures
Replies: 8
Views: 140

Re: Naming Structures

you could either memorize the VSEPR formulas and their shapes or you could draw the lewis structure and figure out the shape based on its number of bonds and lone pairs.
by LilianKhosravi_1H
Sun Jun 03, 2018 5:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How To Know When A Molecule Will Be Bent?
Replies: 4
Views: 108

Re: How To Know When A Molecule Will Be Bent?

You would know the molecule is bent if it has any lone pairs. In the case of water, although it has two bonds that are connected to the H, it also has two lone pairs which push down on the two bonds and make a "bent" shape rather than it being linear.
by LilianKhosravi_1H
Thu May 31, 2018 12:38 pm
Forum: Sigma & Pi Bonds
Topic: Double bond with 2 pi bonds?
Replies: 2
Views: 135

Re: Double bond with 2 pi bonds?

I don't think so, I think a double bond is always 1 sigma and 1 pi bond
by LilianKhosravi_1H
Mon May 28, 2018 1:32 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Meaning
Replies: 5
Views: 172

Re: Formal Charge Meaning

Formal charge is the charge assigned to an atom in a molecule which is why when the molecule has no charge, the formal charges of the individual atoms must equal zero when added up.
by LilianKhosravi_1H
Tue May 22, 2018 9:53 pm
Forum: Lewis Structures
Topic: Radical HW 3.59
Replies: 6
Views: 178

Re: Radical HW 3.59

that's a good question, I also thought we always use formal charge in a scenario like this
by LilianKhosravi_1H
Tue May 22, 2018 8:54 pm
Forum: Lewis Structures
Topic: hwk problem 3.37
Replies: 1
Views: 53

Re: hwk problem 3.37

yeah that's right!
by LilianKhosravi_1H
Sun May 20, 2018 5:03 pm
Forum: Lewis Structures
Topic: Where to put double bonds? [ENDORSED]
Replies: 3
Views: 84

Re: Where to put double bonds? [ENDORSED]

you would probably have to check the formal charges and see which position for the double bonds creates fewer formal charges
by LilianKhosravi_1H
Wed May 16, 2018 9:48 pm
Forum: Ionic & Covalent Bonds
Topic: Question 3.11
Replies: 1
Views: 65

Question 3.11

The question asks which M3+ ions (where M is a metal) are predicted to have the following ground-state electron configurations:
a.) [Ar]3d6
b.) [Ar]3d5
The solutions manual says a is Co3+ and b is Fe3+ but could someone explain how they got this answer?
Thanks!
by LilianKhosravi_1H
Sun May 13, 2018 10:39 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions [ENDORSED]
Replies: 3
Views: 106

Re: Exceptions [ENDORSED]

I think it's because a half full and full orbital are more stable than partially filled d orbital so the electron from 4s goes to 3d.
by LilianKhosravi_1H
Tue May 08, 2018 12:01 pm
Forum: Trends in The Periodic Table
Topic: Octets and ionization energy
Replies: 2
Views: 132

Re: Octets and ionization energy

Ionization energy is the energy needed to remove an electron from an atom. The trend for ionization energy is that it decreases down a group and increases across a period. So it's harder to remove an electron of an atom that has octet e- (8 valence electrons) because it's fully occupied (stable) and...
by LilianKhosravi_1H
Mon May 07, 2018 7:31 pm
Forum: Lewis Structures
Topic: Ammonium Sulfate Example in Notes
Replies: 2
Views: 53

Re: Ammonium Sulfate Example in Notes

To figure out the valence electrons of an elements just count across the periodic tables from the left to the right starting with one and ending with eight. So all the elements in group 1 have one valence electron like H, Li, and Na. N has 5 valence electrons because when you start counting from Li,...
by LilianKhosravi_1H
Sun May 06, 2018 7:37 pm
Forum: SI Units, Unit Conversions
Topic: formula units [ENDORSED]
Replies: 68
Views: 20003

Re: formula units [ENDORSED]

Yeah I had the same question but I think it just means number of atoms.
by LilianKhosravi_1H
Sun May 06, 2018 1:30 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Switching 3d and 4s
Replies: 6
Views: 200

Re: Switching 3d and 4s

When d is occupied by electrons then it becomes lower in energy than s which is when you would put it before s. So elements with 21 electrons or more would have the d come before the s because this is when we first see d become occupied by electrons.
by LilianKhosravi_1H
Tue May 01, 2018 5:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Review Sessions [ENDORSED]
Replies: 3
Views: 133

Re: Review Sessions [ENDORSED]

I was wondering the same thing cause on some of the days my classes conflict with the review sessions planned
by LilianKhosravi_1H
Fri Apr 27, 2018 11:58 am
Forum: DeBroglie Equation
Topic: 1.33 using De Broglie
Replies: 3
Views: 119

Re: 1.33 using De Broglie

for part A you're supposed to find the wavelength of the ejected electron so you would use the De Broglie formula which is wavelength = h/m * V and sub in the numbers (6.626 x 10^-34 J*s)/(9.11x10^-31 kg)(3.6 x 10^6 m/s) which gets you 2.02 x 10^-10 m or 202 pm. h is a constant and so is the mass of...
by LilianKhosravi_1H
Wed Apr 25, 2018 7:38 pm
Forum: Photoelectric Effect
Topic: Calculating kinetic energy of an emitted electron [ENDORSED]
Replies: 3
Views: 130

Re: Calculating kinetic energy of an emitted electron [ENDORSED]

yes the mass is a constant and is on the cover page of the tests so you don't have to worry about memorizing it.
by LilianKhosravi_1H
Tue Apr 24, 2018 2:19 pm
Forum: Properties of Light
Topic: Rydberg Formula for Atomic Hydrogen [ENDORSED]
Replies: 4
Views: 168

Re: Rydberg Formula for Atomic Hydrogen [ENDORSED]

The one on my cover of test 1 is -(hR/n^2), which is the same as the one given in lecture.
by LilianKhosravi_1H
Tue Apr 17, 2018 10:26 pm
Forum: Properties of Light
Topic: units for frequency and wavelength [ENDORSED]
Replies: 9
Views: 181

Re: units for frequency and wavelength [ENDORSED]

proper unit for frequency is Hertz (Hz) which is cycles per second (s^-1) and for wavelength it's usually m (or nm) but it depends on the question because it can ask for the wavelength in a particular unit.
by LilianKhosravi_1H
Tue Apr 17, 2018 1:38 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: HW Question 1.25
Replies: 1
Views: 49

Re: HW Question 1.25

3.37 x 10^-19 J is the answer to part (a) of the problem, it's the energy of an excited sodium atom when it generates a photon. It's then used to figure out the energy of the 5.00 mg of sodium atoms and 1 mole of sodium emitting light at the given wavelength for part (b) and (c).
by LilianKhosravi_1H
Mon Apr 16, 2018 3:02 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Frequency if energy goes from n=2 to n=4
Replies: 6
Views: 176

Frequency if energy goes from n=2 to n=4

So today in lecture we talked about how when the electron goes from n=4 to n=2 the change in energy would be negative and so in return the energy of the photon emitted is positive so in return the frequency is positive. But, if the electron goes from n=2 to n=4 then the change in energy will be posi...
by LilianKhosravi_1H
Sat Apr 14, 2018 9:18 pm
Forum: Properties of Light
Topic: wavelength description [ENDORSED]
Replies: 11
Views: 236

Re: wavelength description [ENDORSED]

The amplitude of a wave is its height, but I also remember Dr. Lavelle saying how as the amplitude increases then the energy or intensity of the wave also increases. He compared it to a wave at the beach saying that a taller wave will be more powerful than a shorter wave.
by LilianKhosravi_1H
Fri Apr 13, 2018 11:57 am
Forum: Limiting Reactant Calculations
Topic: M.2 Example in Textbook
Replies: 1
Views: 74

Re: M.2 Example in Textbook

I was wondering the same thing, I thought they might be typos?
by LilianKhosravi_1H
Tue Apr 10, 2018 4:05 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.11 / Volumes for Solutions
Replies: 2
Views: 78

Re: G.11 / Volumes for Solutions

For this question you don't need to know the final volume since you are given the final mole which is 0.0045 mol C6H12O6 so you can set up your equation as 0.728 M (M=mol x L^-1) x V = 0.0045 mol and to get the initial volume you would divide both sides by 0.728 mol x L^-1 which equals 6.18 x 10^-3 L.
by LilianKhosravi_1H
Mon Apr 09, 2018 9:32 pm
Forum: Properties of Light
Topic: Homework? [ENDORSED]
Replies: 10
Views: 283

Re: Homework? [ENDORSED]

I think it's personal preference, as long as we've gone over the material then you should be fine.
by LilianKhosravi_1H
Mon Apr 09, 2018 9:29 pm
Forum: Properties of Light
Topic: Frequency vs Cycle
Replies: 5
Views: 227

Re: Frequency vs Cycle

I can't remember exactly what Dr. Lavelle said in class, but one cycle per second is a 1 Hertz which equals the frequency. So if there are 2 cycles in one second then the frequency is 2 hertz.
by LilianKhosravi_1H
Sun Apr 08, 2018 4:12 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity formula
Replies: 6
Views: 156

Re: Molarity formula

I think as long as you are given three of those things from the formula then you can use it. You might even be given the mole rather than M or V which you can substitute in place of MiVi since n(moles)=MV

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