CHEMISTRY COMMUNITY

Mallory_Podosin_1H

Going off of this - can someone explain how we decide whether to use it as a base or an acid? Do you just have to look at the other reactant?

Mallory_Podosin_1H

In the equation it goes
acid +base --> conjugate base + conjugate acid

each acid creates a conjugate base which is 1 hydrogen less than the acid
each base creates a conjugate acid which is 1 hydrogen more than the base

Mallory_Podosin_1H

I think the easiest way to recognize is by the presence of a proton. A molecule cannot be a bronsted acid if it doesn't have a hydrogen.

Mallory_Podosin_1H

If you see something like AX 3 E, that means that there are three atoms/molecules surrounding a central atom as well as one lone pair, meaning trigonal pyramidal. A represents the central atom, X represents bonded atoms, and E represents lone pairs. The subscripts represent how many of each of these...

Mallory_Podosin_1H

yes - count lone pairs in hybridization!

Mallory_Podosin_1H

I am pretty sure that it is because of valence electrons, and there are multiple ways to make transition metals stable.
Also - a different oxidation state can make certain molecules neutral and transition metals are the atoms that can change sign most easily...at least that's my understanding.

Mallory_Podosin_1H

They don't occupy the axial positions because the lone pairs want to repel the atoms more than the 90 degrees that set-up would allow. By putting the lone pairs on two of the three equatorial positions, the lone pairs can repel the atoms more effectively and substantially.

Mallory_Podosin_1H

Are the angles the same or different whether it is one lone pair or two lone pairs in the bent shape?
edit - oops just saw the post above...

Mallory_Podosin_1H

Does anyone know if we are expected to be able to draw the structures with the wedges? Or is it just naming the shape?

Mallory_Podosin_1H

I'm not 100% sure but I think the reason that single and double bonds are both considered 1 area of e- density is because for double bonds as well as single bonds, the e- are still in the one same area. VSEPR counts areas of e- density, and a double bond is 1 area of e- density just as single bonds ...

Mallory_Podosin_1H

Single bonds are longer than triple bonds because they are weaker. I am pretty sure this is because there is less pull on the electrons by the nuclei of the atoms that are bonded, so the bond is easier to break when it is longer. In resonance structures, all the bonds between elements with resonance...

Mallory_Podosin_1H

An example of dipole-induced dipole would be when a molecule with a dipole (HCl for example) gets close to a molecule without a dipole. There will be attraction between the positive of the nonpolar molecule and negative part of the dipole (Cl) (or vice versa) - creating a temporary (induced) dipole ...

Mallory_Podosin_1H

hanna_maillard3B wrote:So van-der waals forces work because of induced-dipole induced dipoles ? Do induced-dipole induced-dipole moments affect any other type of bonding or exclusively van-der waals ?

I am pretty sure that induced dipole - induced dipole and Van der Waals forces are two names for the same thing.

Mallory_Podosin_1H

Covalent bonds are associated with the sharing of electrons between two nonmetals while Ionic bonds involve the transfer of electrons between a metal and nonmetal, which involves lattice energy. Ionic bonds are extremely stronger than covalent bonds because of the smaller distance between Ionic bon...

Mallory_Podosin_1H

Is there some kind of a cutoff for how to decide whether or not a dipole is permanent?

Mallory_Podosin_1H

Kind of an extension of this question - so the only way to have a nonpolar covalent bond would be if the electronegativity is the same meaning the same element?

Mallory_Podosin_1H

I am confused on what resonance hybrids are for. Generally and specifically the Benzene Resonance hybrid...so does it only apply to benzene? And also - are there other resonance hybrids?

Mallory_Podosin_1H

Usually (maybe always??) the atom with the lower ionization energy will also have the lower electronegativity so I guess the answer would be both

Mallory_Podosin_1H

For Ionization energy, electron affinity, and electronegativity it Decreases Down and increases across
For atomic radius I just remember that its the other way around

Mallory_Podosin_1H

Spectral lines show that wavelengths are emitted only at certain frequencies. Then by looking at those specific frequencies, you can figure out what the element is because every element has a unique set of spectral lines (wavelengths).

Mallory_Podosin_1H

Often it can be the mass of an electron. Just use the mass of whatever the question asks. Also another trick could be to use the mass of whatever has the velocity.

Mallory_Podosin_1H

I was wondering the same thing... maybe just an exception??

Mallory_Podosin_1H

The way that I remember the SI units for a Joule is by writing out the equations from physics

E = F*d
also F=ma
so,
J=(kg*m*(s^-2))*m
J=kg*m^2*s^-2

Mallory_Podosin_1H

Hi Samantha - Threshold energy has to do with the amount of energy required to release an electron from a metal. The threshold energy changes with whatever kind of metal you are using.

Mallory_Podosin_1H

I am also confused about the Rydberg formula and which one we are supposed to use. Also - is the Rydberg formula only for Hydrogen?

Mallory_Podosin_1H

When doing molarity questions - you have to do all the calculations in Liters because Molarity is moles/Liters. So, it wouldn't make sense to use mL when molarity uses Liters, in other words, the units would not cancel and you would get an incorrect answer. After the problem is solved, however, it c...

Mallory_Podosin_1H

I had this same question... I think that for now it doesn't matter but later on it may start to matter/we will get used to the order in which the elements are listed.

Mallory_Podosin_1H

I don't exactly think that there is a "cutoff" in the lab unless you decided to create your own cutoff for a certain situation? Percent yield is (actual yield/theoretical yield) *100% Actual yield is always going to be less than theoretical yield - so the answer will always be 100% or less...

Mallory_Podosin_1H

On an extended note for this -
What is the difference between M and m? All of the similar variables are confusing me... If someone is interested in simply laying out all the different variables related to Molarity that would be amazingly helpful!

Mallory_Podosin_1H

My only previous chem class was my sophomore year so even stoichiometry feels foreign. I had asked few friends who are good at chem about converting grams to moles using stoichiometry, and they have done it a few different ways but got the same answer. Does anyone have any good tips on how to set u...

Mallory_Podosin_1H

I am VERY rusty on the whole concept of moles...and I am finding it difficult to grasp other concepts without fully understanding moles. Does anyone have any advice on what/how to study and review moles? For example - when to use Avogadro's number, what molar mass is for etc. Any good youtube video ...

CHEMISTRY COMMUNITY

Search found 31 matches

Re: Definition

Re: Clarification of Conjugate Acids and Bases

Re: Difference between Lewis and Bronsted

Re: VSEPR Formula

Re: Lone Pairs in hybridization

Re: Transition metal oxidation states

Re: Lone Pairs on Axial vs. Equatorial Positions

Re: Bent - Lone Pairs

Re: Drawing Structures on Test

Re: VSEPR RULE 3

Re: Bond Length and Resonance

Re: Induced-dipole

Re: Induced-Dipole Induced-Dipole

Re: Ionic vs Covalent Bonds

Re: Permanent Dipole Moments

Re: Polar and Nonpolar

Purpose of Resonance Hybrids

Re: central atoms

Re: Periodic Trends

Re: Spectral Lines and Series

Re: De Broglie's

Re: Ionization Energy

Re: Units of Energy

Re: Threshold energy [ENDORSED]

Re: Rydberg formula

Re: Changing Units

Re: Chemical Formula Element Order

Re: % Yield

Re: V=n/c

Re: Moles!

Moles!