## Search found 31 matches

Sat Jun 09, 2018 2:28 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Aqueous solutions
Replies: 2
Views: 854

### Re: Aqueous solutions

Yes, I think that we will need to know how strong acids and strong bases disassociate in water. I do not believe that we will need to know how to do equations with weak acids and weak bases.

Hope this helps!
Sat Jun 09, 2018 2:26 pm
Forum: Bond Lengths & Energies
Topic: Bond length
Replies: 5
Views: 389

### Re: Bond length

You can look at the number of electrons that are present in each molecule. If there are more lone pairs, they will repel each other and cause a longer bond to be formed.
Wed Jun 06, 2018 7:30 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures on the Final Exam
Replies: 5
Views: 336

### Drawing Lewis Structures on the Final Exam

When we draw Lewis structures on the final exam, do the bond angles need to be accurate?

Thank you!
Sun Jun 03, 2018 7:56 pm
Forum: Hybridization
Topic: Sigma and Pi Bonds
Replies: 5
Views: 300

### Re: Sigma and Pi Bonds

There is always one sigma bond present in a single bond. In a double bond, there is always one sigma bond and one pi bond. A triple bond consists of one sigma bond and two pi bonds, and so on and so forth.

Hope this helps!
Sun Jun 03, 2018 7:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs
Replies: 5
Views: 266

### Re: Lone pairs

Any lone pair present on the central atom will try and repel any of the bonded electrons. This causes the bond angles to lessen slightly and you'll have bond angles that are slightly less than they would be without the presence of the lone pair.

Hope this helps!
Sun Jun 03, 2018 3:13 pm
Forum: Lewis Structures
Topic: Phosphate Lewis structure?
Replies: 4
Views: 340

### Re: Phosphate Lewis structure?

The molecular formula for phosphate is [PO4]3-, so phosphorus will be the central atom, with all of the oxygens connected to it. One of the oxygens will form a double bond with the phosphorus, adding resonance to the structure. All of the oxygens have their octets satisfied.
Sat May 26, 2018 6:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shapes with different types of bonds
Replies: 3
Views: 203

### Re: Shapes with different types of bonds

Yes, I believe that the bond angles will change, due to the repulsive force of electrons.
Sat May 26, 2018 6:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecule Shape
Replies: 1
Views: 140

### Re: Molecule Shape

The VESPR theory does apply to radicals. You can treat the unpaired electron as half of an electron pair. In CH3 there are 7 total electrons, so you will have a trigonal planar shape.
Sat May 26, 2018 6:54 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Valence Bond Theory
Replies: 2
Views: 352

### Re: Valence Bond Theory

The valence bond theory is a chemical bonding theory that explains the bonding between two atoms. This theory states that the bonding is caused by the overlap of two half filled atomic orbitals. The two atoms share each other's unpaired electron to form a filled orbital to form a hybrid orbital and ...
Sat May 19, 2018 6:46 pm
Forum: Lewis Structures
Topic: Dots vs lines to represent electrons
Replies: 8
Views: 459

### Re: Dots vs lines to represent electrons

The lines represent a bond between two atoms. The dots represent lone pairs. You can only use the lines to represent bonds and the dots to represent lone pairs. \

Hope this helps!
Sat May 19, 2018 6:44 pm
Forum: Lewis Structures
Replies: 4
Views: 529

A radical can easily be identified if it has an odd number of valence electrons, since electrons usually come in pairs
Sat May 19, 2018 6:41 pm
Forum: Lewis Structures
Topic: XeO2F2 Lewis Structure [ENDORSED]
Replies: 1
Views: 1007

### XeO2F2 Lewis Structure[ENDORSED]

Why does the central Xenon atom have 12 electrons surrounding it? I am confused as to how to construct the Lewis Dot Diagram for this molecule.

Sun May 13, 2018 5:20 pm
Forum: Ionic & Covalent Bonds
Topic: 3.29
Replies: 6
Views: 286

### Re: 3.29

Coulombic attraction is the force of attraction between positive and negative charges. The coulombic attraction can be calculated using Coulombs law F = kq1q2 / r2 where f= force in newtons k= coulombs constant q1= charge of first particle q2= charge of second particle r= distance between particles ...
Sun May 13, 2018 2:55 pm
Forum: Lewis Structures
Replies: 3
Views: 221

A radical is an atom or molecule that has an unpaired valence electron. Having the unpaired electron makes these elements way more reactive.

Hope this helps!
Sun May 13, 2018 2:54 pm
Forum: Trends in The Periodic Table
Topic: Second Ionization
Replies: 3
Views: 287

### Re: Second Ionization

It is more difficult to remove a second electron, as once you remove a first electron the atom becomes positively charged. The electrons are then pulled closer in to the nucleus, making the second electron harder to remove.
Sat May 05, 2018 2:07 pm
Forum: Molarity, Solutions, Dilutions
Topic: Test 1, Q1 [ENDORSED]
Replies: 4
Views: 448

### Test 1, Q1[ENDORSED]

If someone could walk me through this problem, it would be much appreciated! A) Lithium carbonate, Li2CO3, is a salt that is used for the treatment of bipolar disorder. A solution of lithium carbonate is prepared by dissolving 2.0 g of salt to 1.00 L water. What is the concentration of lithium ions ...
Fri May 04, 2018 8:04 pm
Forum: Properties of Light
Topic: Frequency and Wavelength
Replies: 3
Views: 266

### Re: Frequency and Wavelength

Frequency and wave length are inversely proportional. When frequency increases, wavelength decreases, and vice versa!

Hope this helps!
Fri May 04, 2018 8:03 pm
Forum: Properties of Light
Topic: Sig Figs [ENDORSED]
Replies: 3
Views: 277

### Sig Figs[ENDORSED]

Will we need to use Sig Figs on the midterm? Ive heard many different answers from different people.

Thanks!
Wed May 02, 2018 9:01 pm
Forum: Trends in The Periodic Table
Topic: Periodic Table Trends on the Midterm
Replies: 4
Views: 279

### Re: Periodic Table Trends on the Midterm

I'm pretty sure that the midterm only contains material from the first two chapters! So everything up until chemical bonds in todays lecture I think.

Hope this helps!
Thu Apr 26, 2018 2:09 pm
Forum: Quantum Numbers and The H-Atom
Topic: Fourth Quantum Number
Replies: 5
Views: 303

### Re: Fourth Quantum Number

The fourth quantum number is used to indicate the orientation of the two electrons in each orbital. The values for ms are +1/2 and -1/2. An atom is the most stable when its electrons have the lowest possible energy. I think that you will be able to determine what the fourth quantum number is based o...
Thu Apr 26, 2018 2:08 pm
Forum: Properties of Electrons
Topic: Spin Magnetic Quantum Number
Replies: 2
Views: 230

### Re: Spin Magnetic Quantum Number

The fourth and final quantum number is used to indicate the orientation of the two electrons in each orbital. The values for ms are +1/2 and -1/2. An atom is the most stable when its electrons have the lowest possible energy.

Hope this helps!
Thu Apr 26, 2018 2:06 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes [ENDORSED]
Replies: 6
Views: 345

### Re: Nodal Planes[ENDORSED]

A nodal plane is a plane in which the probability of finding a electron is zero. The 2s orbital has a nodal shell, whereas the 2pz orbital or 2p orbitals have a nodal plane.

Hope this helps!
Sat Apr 21, 2018 3:21 pm
Forum: Photoelectric Effect
Topic: Photoelectric Post-Module [ENDORSED]
Replies: 3
Views: 221

### Re: Photoelectric Post-Module[ENDORSED]

A) To find the kinetic energy, use KE= 1/2mv^2. the velocity is given and the mass of an electron is a constant B) divide the work function by avogadro's number, as it is currently in moles. C) use KE= hv - (work function). you know the work function, the kinetic energy, and Plank's constant, so you...
Thu Apr 19, 2018 7:40 pm
Forum: Properties of Light
Topic: units for frequency and wavelength [ENDORSED]
Replies: 9
Views: 392

### Re: units for frequency and wavelength[ENDORSED]

As others have said, frequency is measured in Hertz, or cycles per second. Wavelength is measured in meters.

Hope this helps!
Wed Apr 18, 2018 11:00 pm
Forum: Properties of Electrons
Topic: Practice Problem
Replies: 1
Views: 173

### Practice Problem

If 3.607 x 10-19 J is required to remove an electron with zero kinetic energy from a metal surface, what would be the longest wavelength light that could do this? From a previous chemistry community post, I know that you use the KE = energy of a photon + work function equation, but I am confused as ...
Thu Apr 12, 2018 10:02 am
Forum: Molarity, Solutions, Dilutions
Topic: Mass percentage
Replies: 8
Views: 533

### Re: Mass percentage

You have to find the mass of the elements that are given and convert the masses to percentages, assuming that it is out of 100%. It should always add up to 100 if you carry out the problem in this fashion.

Hope this helps!
Thu Apr 12, 2018 9:59 am
Forum: Balancing Chemical Reactions
Topic: Fractions in chemical equations [ENDORSED]
Replies: 5
Views: 675

### Re: Fractions in chemical equations[ENDORSED]

It is basically impossible to spilt an atom, which is what you are implying if you have a fraction in your chemical equation.

Hope this helps!
Thu Apr 12, 2018 9:57 am
Forum: SI Units, Unit Conversions
Topic: Moles mols mol? [ENDORSED]
Replies: 21
Views: 2321

### Re: Moles mols mol?[ENDORSED]

Hi!

I don't think it matters. All of them mean the same thing.

Hope this helps!
Fri Apr 06, 2018 12:31 pm
Forum: Limiting Reactant Calculations
Topic: General Process [ENDORSED]
Replies: 3
Views: 240

### Re: General Process[ENDORSED]

If the problem gives you the the amount of moles of each reactant, you can determine the limiting reagent easily by looking at the given amount of moles and comparing it to the number of moles in the given chemical equation (the stoichiometric coefficients). Otherwise, I normally conduct the problem...
Fri Apr 06, 2018 12:26 pm
Forum: Empirical & Molecular Formulas
Topic: Determining Molecular Formula Based on Name of Molecule [ENDORSED]
Replies: 5
Views: 276

### Re: Determining Molecular Formula Based on Name of Molecule[ENDORSED]

You need to know the charges of the elements before you can determine the empirical formula. The charge of boron is +3 and the charge of oxygen is -2. In order for the atom to have a neutral charge, you must have two molecules of boron and 3 molecules of oxygen. This will give you the empirical form...
Fri Apr 06, 2018 12:22 pm
Forum: Significant Figures
Topic: Sig Figs [ENDORSED]
Replies: 9
Views: 566

### Sig Figs[ENDORSED]

Do we need to always use significant figures on tests and homework assignments?