CHEMISTRY COMMUNITY

Alan Chang

Which HW question is question 17 similar to?

Alan Chang

How can we know what type of forces are present in different molecules? For example, how can we know if a molecule undergoes dipole dipole, dipole induced dipole, or other types of forces?

Alan Chang

In lectured we learned that weaker A-H bonds will be more acidic because they lose H+ more easily, but isn't HCl a strong base despite its relatively strong H-Cl bond? Can someone help me? I'm pretty confused.

Alan Chang

Does anyone know what the geometry of a chelate compound would be?

Alan Chang

Lewis acids are electron pair acceptors in a reaction and Lewis bases are electron pair donors in a reaction.

Alan Chang

How much should we know about these compounds for the test?

Alan Chang

Some amphoteric compounds you can also deduce. For example, seeing water, you can deduce that it can lose its H+ ion (proton) to form OH- (acting as Bronsted acid) and you can deduce that it can accept a H+ ion (proton) to form H3O+ (acting as Bronsted base) therefore deducing that it is amphoteric.

Alan Chang

Can someone explain to me how the lone pairs on a compound have to be geometrically arranged in order to be a polydentate ligand? Like does the compound have to be a certain shape? or do the lone pairs have to be far part from each other on the compound?

Alan Chang

I was wondering if we have to know the oxidation states of elements in a compound for naming coordinate compounds on the exam. Because in the textbook, there were questions that wanted us to write the oxidation states of the metal when naming the compound, but to get that we will have to know the ox...

Alan Chang

I was wondering if knowing whether the central atom has single, double, or triple bonds would help in determining its hybridization.

Alan Chang

I believe you will only have to look at the regions of electron density for the atom asked for. For example, they might ask for the hybridization of a certain carbon in caffeine.

Alan Chang

the pi bond wraps around the sigma bond in a double bond, and can only form when a sigma bond is present, but no, a pi bond is only a pi bond.

Alan Chang

The only linear structure I can think of is AB2E3 are there any more?

Alan Chang

Lone pairs affect the molecular shape, but only atoms are used when naming the shape. For example, a trigonal pyramidal structure is actually a tetrahedral formation of electron densities, but only the atoms are counted towards the shape, thus the shape is trigonal pyramidal.

Alan Chang

They are still referred to one region of electron density, therefore they act the same as single bonds

Alan Chang

In the midterm it was asking for the resonance bond length, so in this case we can take the average of the single and double bond to make an estimate of the bond length.

Alan Chang

Polar molecules are more soluble in polar solvents and non polar molecules are more soluble in non polar solvents. In this case, water is polar, so polar compounds are more soluble in water.

Alan Chang

Hydrogen bonds are the strongest intermolecular forces.

Alan Chang

Can some one help me with all the octet exceptions we need to know for the test? Thanks~

Alan Chang

What I do is I draw a circle around each atom, so you count one electron for each bond and two electrons for each lone pair. Then you just take the valence electrons of the atom and minus it by how much you count.

Alan Chang

The resonance hybrid is whats actually going on in a resonance structure I think. Like the two resonance structures of benzene is just to show what the actual resonance hybrid is an average of.

Alan Chang

Most follow the octet rule, but there are exceptions. For example there are the ones Dr. Lavelle mentioned in the lecture, and the expanded octet (I don't know if we will learn about this though).

Alan Chang

In the lecture it is said that the 3d orbital will be lower in energy than the 4s orbital in all cases where the 4s orbital is filled. But does this mean that there are cases where the 3d orbital has higher energy than the 4s orbital?

Alan Chang

Is it better to always change the units into the standard units used in the equation before calculations are done?

Alan Chang

I attached an image below that should explain this pretty well. As you can see the px orbital is two lobes that run along the x orbital, and the same goes for the py and pz orbitals.

Alan Chang

Can anyone explain why the diameter of an atom is typically used for Delta x in the equation? Also, are there any other values that can be used?

Alan Chang

It is an unit of energy called an kilo-electronvolt.
One KeV is 1000 eV, and 1 eV = 1.602 × 10-19 J
Its on the Constants and Equations page that can be found on the class website! :)

Alan Chang

Just remember that molarity (M) is always 1 mole/Liter or 1 mole/1000 ml. If you keep this in mind you should be good to go no matter what units you are dealing with or end up with.

Alan Chang

Yes, a combustion reaction always has oxygen as the reactants and carbon dioxide and water and products.

Alan Chang

Its also important that during addition or subtraction, the value with the least amount of decimal spaces should be used instead of sig figs.

Alan Chang

When an electron transfers from a lower energy level to a higher energy level, energy is absorbed and the atom becomes less stable.

Alan Chang

In class, we discussed wavelengths that were so small that they were considered unmeasurable. However, I didn't quite catch the minimum value for which a wavelength is considered "measurable." Does anyone know this?

Alan Chang

I think the car has no wavelength properties because something with a mass so large would produce a very small wavelength according to the equation. In the car's case, the wavelength would be so small that would be unmeasurable.

CHEMISTRY COMMUNITY

Search found 33 matches

Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

Forces Present in molecules

Relative acidity questions

Chelate geometry

Re: Simple Question: What are they?

Hemoglobin Myoglobin details for test

Re: Amphoteric Compounds

Polydentate ligand geometry

Knowing oxidation states

Single, Double, and Triple Bonds

Re: Hybridization of large molecules

Re: double bonds

Linear structure with lone pairs

Re: Lone pairs determining shape?

Re: double and triple bonds

Re: bond length such as the midterm question

Re: Solubility in Water

Re: Hydrogen Bonds

What are the octet exceptions?

Re: shortcut for FC

Re: Purpose of Resonance Hybrids

Re: the Octet rule

D and P orbital energies

Re: Units

Re: orientation of the lobes

Delta x

Re: 6th HW 1.23 What is KeV?

Re: Units?

Re: question on "combustion" and "cooking"

Re: knowing how many sig figs to use

Re: energy transitions

Measurable wavelengths

Re: Car Example in Class with De Brogile Equation