Search found 33 matches

by Alan Chang
Sat Dec 08, 2018 6:15 pm
Forum: Dipole Moments
Topic: Forces Present in molecules
Replies: 3
Views: 219

Forces Present in molecules

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?
by Alan Chang
Sat Dec 08, 2018 12:25 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Relative acidity questions
Replies: 1
Views: 49

Relative acidity questions

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.
by Alan Chang
Fri Dec 07, 2018 11:53 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelate geometry
Replies: 2
Views: 64

Chelate geometry

Does anyone know what the geometry of a chelate compound would be?
by Alan Chang
Fri Dec 07, 2018 11:50 pm
Forum: Lewis Acids & Bases
Topic: Simple Question: What are they?
Replies: 1
Views: 50

Re: Simple Question: What are they?

Lewis acids are electron pair acceptors in a reaction and Lewis bases are electron pair donors in a reaction.
by Alan Chang
Fri Dec 07, 2018 11:46 pm
Forum: Biological Examples
Topic: Hemoglobin Myoglobin details for test
Replies: 1
Views: 193

Hemoglobin Myoglobin details for test

How much should we know about these compounds for the test?
by Alan Chang
Sun Dec 02, 2018 8:55 pm
Forum: Amphoteric Compounds
Topic: Amphoteric Compounds
Replies: 5
Views: 151

Re: Amphoteric Compounds

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.
by Alan Chang
Sun Dec 02, 2018 8:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate ligand geometry
Replies: 1
Views: 64

Polydentate ligand geometry

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?
by Alan Chang
Sun Dec 02, 2018 8:46 pm
Forum: Naming
Topic: Knowing oxidation states
Replies: 11
Views: 147

Knowing oxidation states

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...
by Alan Chang
Sun Nov 25, 2018 1:03 am
Forum: Hybridization
Topic: Single, Double, and Triple Bonds
Replies: 1
Views: 38

Single, Double, and Triple Bonds

I was wondering if knowing whether the central atom has single, double, or triple bonds would help in determining its hybridization.
by Alan Chang
Sun Nov 25, 2018 12:56 am
Forum: Hybridization
Topic: Hybridization of large molecules
Replies: 2
Views: 56

Re: Hybridization of large molecules

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.
by Alan Chang
Sun Nov 25, 2018 12:41 am
Forum: Hybridization
Topic: double bonds
Replies: 14
Views: 228

Re: double bonds

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.
by Alan Chang
Sun Nov 25, 2018 12:38 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear structure with lone pairs
Replies: 6
Views: 142

Linear structure with lone pairs

The only linear structure I can think of is AB2E3 are there any more?
by Alan Chang
Sun Nov 25, 2018 12:34 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs determining shape?
Replies: 5
Views: 122

Re: Lone pairs determining shape?

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.
by Alan Chang
Sun Nov 25, 2018 12:30 am
Forum: Determining Molecular Shape (VSEPR)
Topic: double and triple bonds
Replies: 10
Views: 186

Re: double and triple bonds

They are still referred to one region of electron density, therefore they act the same as single bonds
by Alan Chang
Mon Nov 12, 2018 6:46 pm
Forum: Bond Lengths & Energies
Topic: bond length such as the midterm question
Replies: 5
Views: 132

Re: bond length such as the midterm question

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.
by Alan Chang
Mon Nov 12, 2018 6:42 pm
Forum: Dipole Moments
Topic: Solubility in Water
Replies: 5
Views: 143

Re: Solubility in Water

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.
by Alan Chang
Mon Nov 12, 2018 6:39 pm
Forum: Dipole Moments
Topic: Hydrogen Bonds
Replies: 20
Views: 310

Re: Hydrogen Bonds

Hydrogen bonds are the strongest intermolecular forces.
by Alan Chang
Sun Nov 04, 2018 1:54 pm
Forum: Octet Exceptions
Topic: What are the octet exceptions?
Replies: 9
Views: 227

What are the octet exceptions?

Can some one help me with all the octet exceptions we need to know for the test? Thanks~
by Alan Chang
Sun Nov 04, 2018 1:52 pm
Forum: Formal Charge and Oxidation Numbers
Topic: shortcut for FC
Replies: 6
Views: 163

Re: shortcut for FC

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.
by Alan Chang
Sun Nov 04, 2018 1:49 pm
Forum: Resonance Structures
Topic: Purpose of Resonance Hybrids
Replies: 4
Views: 110

Re: Purpose of Resonance Hybrids

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.
by Alan Chang
Sun Oct 28, 2018 9:27 pm
Forum: Ionic & Covalent Bonds
Topic: the Octet rule
Replies: 21
Views: 431

Re: the Octet rule

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).
by Alan Chang
Sun Oct 28, 2018 9:22 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: D and P orbital energies
Replies: 3
Views: 96

D and P orbital energies

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?
by Alan Chang
Sun Oct 28, 2018 9:15 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Units
Replies: 8
Views: 201

Re: Units

Is it better to always change the units into the standard units used in the equation before calculations are done?
by Alan Chang
Fri Oct 19, 2018 5:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: orientation of the lobes
Replies: 2
Views: 35

Re: orientation of the lobes

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.
by Alan Chang
Fri Oct 19, 2018 4:48 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Delta x
Replies: 2
Views: 38

Delta x

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?
by Alan Chang
Fri Oct 19, 2018 4:41 pm
Forum: DeBroglie Equation
Topic: 6th HW 1.23 What is KeV?
Replies: 5
Views: 152

Re: 6th HW 1.23 What is KeV?

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! :)
by Alan Chang
Sat Oct 13, 2018 3:54 pm
Forum: Molarity, Solutions, Dilutions
Topic: Units?
Replies: 8
Views: 353

Re: Units?

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.
by Alan Chang
Sat Oct 13, 2018 3:51 pm
Forum: Balancing Chemical Reactions
Topic: question on "combustion" and "cooking"
Replies: 3
Views: 289

Re: question on "combustion" and "cooking"

Yes, a combustion reaction always has oxygen as the reactants and carbon dioxide and water and products.
by Alan Chang
Sat Oct 13, 2018 3:50 pm
Forum: Significant Figures
Topic: knowing how many sig figs to use
Replies: 17
Views: 694

Re: knowing how many sig figs to use

Its also important that during addition or subtraction, the value with the least amount of decimal spaces should be used instead of sig figs.
by Alan Chang
Sat Oct 13, 2018 3:47 pm
Forum: Properties of Electrons
Topic: energy transitions
Replies: 6
Views: 116

Re: energy transitions

When an electron transfers from a lower energy level to a higher energy level, energy is absorbed and the atom becomes less stable.
by Alan Chang
Sat Oct 13, 2018 3:43 pm
Forum: Properties of Light
Topic: Measurable wavelengths
Replies: 5
Views: 77

Measurable wavelengths

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?
by Alan Chang
Sat Oct 13, 2018 3:39 pm
Forum: Properties of Light
Topic: Car Example in Class with De Brogile Equation
Replies: 8
Views: 112

Re: Car Example in Class with De Brogile Equation

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.

Go to advanced search