CHEMISTRY COMMUNITY

Haorui Li 1A

What will the question be like if we have Amphoteric Compounds questions on final?

Haorui Li 1A

When no lone pairs of electrons are present, the electronic geometry is the same as the molecular shape. Things are different when a lone pair is presented. Different molecules with the same geometry shape can have different molecular shapes depend on the number of their lone pairs.

Haorui Li 1A

Can Pi bonds be considered just a force of attraction between electron pairs?

Haorui Li 1A

To form bonds, CH4, for example, the central Carbon needs to form 4 bonds with 4 H to form one CH4 molecule. Thus, there are 4 regions of electron density around the C, so we know that C is sp3 hybridized.

Haorui Li 1A

The electron pairs donor is considered to be Lewis base, an N with a lone pair is able to donate its lone pair and form bonds, so it is considered a Lweis base.

Haorui Li 1A

Two-way double half arrows represent a reaction that can go either forward or reverse. Whether the reaction shifts or not depends on Le Chatlier's principle. In the lecture, strong acids used double arrows but weak acids used single arrows.

Haorui Li 1A

I think the Lewis structure of (CH3)2 Be should be linear. Beryllium would be the central atom, and it forms two bonds, one to each Carbon of the CH3. Each Carbon is bonded to Beryllium and to 3 hydrogens so it has 4 bonds.

Haorui Li 1A

Can someone explain why is BeCl2 sp hybridized? Why are there only 4 electrons around Be in the Lewis structure?

Haorui Li 1A

The formal charge is just a way for you to rearrange the position of each element in the Lewis structure, meaning by applying formal charge, you can find the relative most stable structure. Partial charge is for you to see if the molecule is polar. It is represented by the Greek lowercase letter δ, ...

Haorui Li 1A

Dipoles are usually polar, but I think the VSEPR shapes determine if the dipoles can cancel out. If the dipoles can be canceled out, for example, tetrahedral, then the molecule will not be polar.

Haorui Li 1A

Intramolecular forces are the forces that hold atoms together within a molecule. There are 3 types of intramolecular bonds: covalent, ionic, and metallic. Intermolecular forces are forces that exist between molecules. Key intermolecular forces are as follows: Hydrogen bonding > Van der Waals dipole-...

Haorui Li 1A

After you get the empirical formula, you get the molar mass of the empirical formula of the compound. If you need to find the molecular formula, the question will give you the molar mass of the molecular formula. Now you divide the molar mass of the molecular formula by the molar mass of the empiric...

Haorui Li 1A

I think the formal charge is just a way to provide you a possible more stable Lewis structure.

Haorui Li 1A

Ion-dipole forces can be generated between polar water molecules and a sodium ion. The oxygen atom in the water molecule has a slight negative charge and is attracted to the positive sodium ion. These intermolecular ion-dipole forces are much weaker than covalent or ionic bonds.

Haorui Li 1A

Intramolecular forces are the forces that hold atoms together within a molecule. There are 3 types of intramolecular bonds: covalent, ionic, and metallic. Intermolecular forces are forces that exist between molecules. The four key intermolecular forces are as follows: Ionic bonds > Hydrogen bonding ...

Haorui Li 1A

I learned this in high school, but can someone explain why when we draw the Lewis structures, Aluminum and Boron have only 6 electrons around them and they satisfy the octet rule?

Haorui Li 1A

The octet rule can be ‘expanded’ by some elements by utilizing the d- orbitals found in the third principal energy level and beyond. For the elements in the second period of the periodic table (principal energy level n=2), the s2p6 electrons comprise the octet, and no d sublevel exists. As a result,...

Haorui Li 1A

The magnitude of the electric force between q1 and q2 is directly proportional to the magnitude of the charges and inversely proportional to the square of the distance between them. This equation is known as Coulomb’s Law.

Haorui Li 1A

The amplitude of a wave refers to the maximum amount of displacement of a particle on the medium from its rest position. The amplitude can be measured from the rest position to the trough position.

Haorui Li 1A

Here is how I answered it. Hope it helps.

Haorui Li 1A

In this question, it asks "What is the net number of moles of gas produced?", so we look at compounds that are in the gas phase. In the chemical equation, all compounds are in the gas phase, so to calculate the net number, we just calculate the net change from reactants to products. If the...

Haorui Li 1A

You cannot add a product to the chemical equation because a chemical equation describes a chemical reaction, it is an expression that gives the identities and quantities of the substances involved in a reaction, if the product was not there originally, you cannot add one. Balancing chemical equation...

Haorui Li 1A

I think if we don't have the correct sig. fig. the points will be deducted even if you have correct answers.

Haorui Li 1A

(aq) means aqueous solutions, which means the solvent of the solution is water. It depends on the statement in the question, but I believe for most solutions we use (aq) (e.g. NaOH(aq) and HCL(aq) ), and H2O should be (l).

Haorui Li 1A

Since the chemical equation is balanced, we can see 1 mole of C reacts with 1 mole of O2 to form 1 mole of CO2. The ratio to carbon, oxygen and carbon dioxide are 1:1:1, so if there are 1mol carbon atoms and 1mol oxygen molecules, 1 mol of CO2 will be formed so there will be no limiting reactant. Ho...

Haorui Li 1A

The unit for atomic mass is in amu, however, the unit for molar mass is g/mol.

Haorui Li 1A

In the discussion 1A, we solved a practice problem about the empirical formula and molecular formula, I just want to know how do we determine the order of the element in a compound if there are 3 or more. For example, the question that we did in class was about Os, O and C. The answer was OsC4O4, I ...

Haorui Li 1A

I believe Dr.Lavelle said since the molar mass is always in grams per mole, we tend to use grams in questions and the grams tend to cancel out each other. Can someone explain more?

Haorui Li 1A

Properties of Light: 1.Wavelength(λ) a. Distance between two consecutive peaks or troughs in a wave b. Measured in meters (SI system) 2. Frequency(ν) a. The number of waves that pass a given point per second b. Measured in hertz (sec-1) 1Hz=1 (1/s) 3. Speed(c) a. Measured in meters/sec b. Speed in V...

Haorui Li 1A

What is the unit for theoretical yield or actual yield? In the example Dr. Lavelle provided in class the unit was in grams, does it always need to be in grams or based on different questions the unit changes?

CHEMISTRY COMMUNITY

Search found 30 matches

Re: pH of Amphoteric Compounds

Re: Geometry vs molecular shape

Re: Sigma/pi bonds

Re: Hybridizing orbitals [ENDORSED]

Re: Nitrogen as a Base

Re: Back and Fourth Arrows

Re: question 4.19

Hybridization

Re: Complete Lewis Structure [ENDORSED]

Re: Dipoles

Re: Inter and Intra

Re: Formulas

Re: Which do you prioritize first

Re: Ion-Dipole

Re: Intermolecular vs. Intramolecular forces

Aluminum and Boron [ENDORSED]

Re: Expanded octet

Re: Electrostatic Potential Energy Formula

Re: wavelength

Re: 4b on Test 1

Re: Balancing Equations

Re: balancing reaction law

Re: Determining sig figs

Re: Elemental states [ENDORSED]

Re: How to distinguish limiting or excess reactant.

Re: Molar Mass vs. Atomic Weight

How to determine the order of elements? [ENDORSED]

Re: Can someone explain why we use kg for mass as the base unit?

Re: Light variables

Theoretical/Actual Yield