CHEMISTRY COMMUNITY

Keshav Bhatnagar 1H

What exactly do we have to know from the acid base chapter for the final? I'm a little confused because we didn't cover some of the outline material in class.

Keshav Bhatnagar 1H

The hybridization of NH3 would be sp3. In hybridization you count the number of electron densities and the lone pair is an electron density.

Keshav Bhatnagar 1H

Between two atoms. For ex. in Li-F, F is very electronegative thus the electrons in Li are pulled heavily towards the F resulting in a dipole (positive charge on Li and negative carge on F).

Keshav Bhatnagar 1H

I believe the UA meant to say that hybridization tells us the number of electron densities. To my knowledge, you can't find out the number of bonds based on hybridization at least for triple bonds.. I'm not sure about this but, the only way you could find a double bond based on hybridizaton could be...

Keshav Bhatnagar 1H

Oxidation numbers can be negative too. It describes the number of electrons lost or gained.

Keshav Bhatnagar 1H

In order to find the electron - pair geometry, you need to count all electron densities including lone pairs. In order to find the molecular geometry, again you need to count all electron densities but especially be aware of how many lone pairs there are on the central atom. This is because the mole...

Keshav Bhatnagar 1H

I will give an example that will hopefully help: Consider CH3Cl. It will be in a tetraderal shape and because chlorine is so electronegative it will have a slight negative charge thus creating a dipole. Consider CH2Cl with the Cl on opposite sides. This will also be in a tertrahedral shape, but the ...

Keshav Bhatnagar 1H

annabel 1F wrote:If there is a double bond will there always be 1 sigma and 1 pi bond?

Yes, the first bond is always a sigma bond, but bonds after that are pi bonds.

Keshav Bhatnagar 1H

I believe the shape would be square planar. The two N atoms would be in the center with a bond between them and the H would surround them. This would result in 6 electron densities with two being lone pairs thus a square planar arrangement.

Keshav Bhatnagar 1H

Try to think about it logically. Square planar has 6 electron densities with 2 densities being lone pairs and the other 4 being atoms with electrons. Lone pairs have the most repulsion and electrons want to be as far away as possible, so the preferred shape would be square planar with bond angles of...

Keshav Bhatnagar 1H

Molecular shapes include: Linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral. Note that in order to determine molecular shape you ignore the repulsion of lone pairs of electrons and only count the electron densities. Electron geometry includes: Bent, trigonal pyramid, seesaw,...

Keshav Bhatnagar 1H

It occurs due to the electron repulsions and the bond angle varies based on how the elements and their electrons interact with other elements and their electrons. If you can give a specific example of your question I can elaborate.

Keshav Bhatnagar 1H

When you have two electron clouds, how do you figure out if the shape is linear or angular? Same thing with trigonal; If you have 3 electron clouds how do you figure out if the shape is trigonal planar or trigonal pyramidal?

Keshav Bhatnagar 1H

cara_cavarretta_3F wrote:Is this for all discussions or just for Thursday and Friday discussions?

All

Keshav Bhatnagar 1H

Free valence electrons (based on periodic table ) - bonded valence electrons (based on the element given)

Keshav Bhatnagar 1H

You should know that elements in the first and second periods can have expanded valence shells due to the empty d-orbital. You should also know that Cu and Cr have electron configuration exceptions.

Keshav Bhatnagar 1H

You don't have a line connecting two ionic compounds otherwise it would mean they have a covalent bond. To write an ionic bond, you would just put the elements in brackets and indicate their charge outside the bracket.

Keshav Bhatnagar 1H

My question is, if the formal charge is 0 for all atoms in the bond, is are there resonance structures? Even though there may be a compound with a formal charge of 0, that doesn't necessarily mean the compound doesn't have any resonance structures. You need to play around with double bonds and delo...

Keshav Bhatnagar 1H

If resonance structures are supposed to be more stable, why don't we see more molecules in a resonance form in nature?

Keshav Bhatnagar 1H

If you check the solutions manual, [Ar]3d^8 is the correct answer.

Keshav Bhatnagar 1H

I think you meant ClO-?

If that is the case then you can only draw it with a single bond; a double bond would result in either Cl or O needing to expand their valence shell in order to take in a lone electron.

Keshav Bhatnagar 1H

If the visible light's energy is greater than or equal to the work function of the metal then yes, but I can't think of a metal off the top of my head.

Keshav Bhatnagar 1H

The E in E = hv represents the energy of a photon. The E in Ek = 1/2(mv^2) represents the excess energy after an electron is removed from a metal.

Keshav Bhatnagar 1H

It means having orbitals that are in the same energy level. So for the s-orbital it would be 1, p would be 3 and so on.

Keshav Bhatnagar 1H

Convert from Mg to moles to atoms, so 0.0050g x 1mol/22g x 6.022(10^23)/1 mol. Multiply this value by the answer you got in part A.

For part C, it is the same thing. All you have to do is multiply by avogadros number then multiply that value by the answer you got in part A.

Hope that helps!

Keshav Bhatnagar 1H

Hi, I'm not sure how to do this problem and the solutions manual doesn't really help. Here is the problem: A lamp rated at 32 W (1 W 1 Js1) emits violet light of wavelength 420 nm. How many photons of violet light can the lamp generate in 2.0 s? How many moles of photons are emitted in that time...

Keshav Bhatnagar 1H

Increasing the intensity is not a form of increasing energy. Increasing intensity only means more photons are present, which doesn't change the overall energy level. However, increasing the frequency increases the overall energy level.

Keshav Bhatnagar 1H

When an electron gains energy it goes to a higher orbital (further from the nucleus). When an electron loses energy, it releases the energy as light (photons) and depending upon how much energy is released, the electron travels to a lower orbital.

Keshav Bhatnagar 1H

Yes, the cutoff is at 10^-18

Keshav Bhatnagar 1H

Can someone please explain G13? "To prepare a fertilizer solution, a florist dilutes 1.0 L of 0.20 m NH4NO3(aq) by adding 3.0 L of water. The florist then adds 100. mL of the diluted solution to each plant. How many moles of nitrogen atoms will each plant receive? Solve this exercise without us...

Keshav Bhatnagar 1H

Yes, I believe you always assume that the compound has a total mass of 100g simply because it is much easier to solve with this assumption.

Keshav Bhatnagar 1H

Please explain problem E3 in the fundamental exercises.

CHEMISTRY COMMUNITY

Search found 32 matches

Regarding the final

Re: lone pairs of e-

Re: Differences in electronegativity

Re: How does hybridization tell us the # of bonds?

Re: Oxidation Numbers

Re: Trigonal Planar or Trigonal Pyramidal?

Re: Dipoles

Re: Sigma and Pi bonds

Re: No central atom

Re: Square Planar

Re: Molecular shape vs. Electron Geometry [ENDORSED]

Re: Bond Angles

Linear vs angular and trigonal planar vs trigonal pyramidal

Re: Homework Week 8 [ENDORSED]

Re: Formal Charge Equation

Re: Exceptions to Octet Rule

Re: Ionic compound

Re: Tricks for Resonance Structures

Resonance Structures

Re: 3.19 (6th edition)

Re: Formal Charge

Re: Frequency of light

Re: E=hv [ENDORSED]

Re: Degeneracy

Re: HW Problem 1.25 (6th Edition)

Chapter 1 Question 27

Re: Photoelectric Experiment

Re: Energy emitted by electrons

Re: Measurable Wavelengths

Homework Problem in Section G

Re: Empirical Formula

Fundamental Exercises E3 [ENDORSED]