Search found 30 matches

by Louis Zhao 4C
Sat Dec 08, 2018 8:33 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating pH or pOH with Molarity
Replies: 3
Views: 40

Re: Calculating pH or pOH with Molarity

Dr. Lavelle might give us a multistep question to involves both fundamentals as well as acids and bases. So he might first ask for us to calculate the molarity of a solution by only giving us the amount of substance and the total volume of the solution, and then ask us to find the pH of the solution.
by Louis Zhao 4C
Sat Dec 08, 2018 12:56 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strength of Acids vs. Number of Oxygens
Replies: 3
Views: 44

Strength of Acids vs. Number of Oxygens

Why does the strength of an acid increase with the oxidation number of the central atom and the number of oxygens bonded to the central atom?
by Louis Zhao 4C
Fri Dec 07, 2018 5:54 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Myoglobin coordination compound
Replies: 1
Views: 23

Myoglobin coordination compound

Why can myoglobin only bind to one O2 molecule when iron ions can bind up to 2 ligands after being bonded with the HEME Complex. The HEME complex in myoglobin has 4 binding locations so shouldn’t iron be able to take 2 O2 molecules instead of 1?
by Louis Zhao 4C
Sun Dec 02, 2018 1:39 pm
Forum: Naming
Topic: Ligands
Replies: 2
Views: 39

Re: Ligands

A Ligand is a polydentate if it has two or more atoms that have lone pairs and can therefore bind to a metal ion. I found this website to be extremely helpful in defining the various types of ligands :
https://www.chemicool.com/definition/ligand.html
by Louis Zhao 4C
Sun Dec 02, 2018 1:27 pm
Forum: Naming
Topic: H20 monodentate
Replies: 1
Views: 24

Re: H20 monodentate

Polydentates refers to the number of atoms capable of bonding to a central metal ion. Although H2O has two lone pairs, they are both on the Oxygen atom, thus making the molecule a monodentate.
by Louis Zhao 4C
Sun Dec 02, 2018 1:19 pm
Forum: Lewis Acids & Bases
Topic: Weak Acid/Base vs. Strong
Replies: 7
Views: 65

Weak Acid/Base vs. Strong

What is the best way to differentiate between a strong acid/base and a weak acid/base. For example how do we know ammonia is a weak base while sodium hydroxide is a strong base and acetic acid is a weak acid while HCl is a strong acid.
by Louis Zhao 4C
Sun Nov 25, 2018 5:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Hw: Ch.4 #73 (6th Edition)
Replies: 2
Views: 40

Re: Hw: Ch.4 #73 (6th Edition)

CH2^2- has a Lewis structure similar to H2O, where the central atom (C) is bonded to two hydrogen atoms and has two unpaired electron pairs. This corresponds to a VESPR Formula of AX2E2 which has a bond angle of 104.5. The lone pairs are not directly opposite of each other but are at an angle of 104...
by Louis Zhao 4C
Sat Nov 24, 2018 11:03 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3
Replies: 9
Views: 117

Re: Test 3

I think test 3 will cover all the information in the Molecular Shape and Structure Outline along with the rest of chapter 3 from 3.12 onward, so Ionic bonds vs. Covalent bonds, and Bond shape and bond strength.
by Louis Zhao 4C
Sat Nov 24, 2018 10:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR model formula
Replies: 3
Views: 37

Re: VSEPR model formula

The VSEPR model formula is a representation of the 3D structure of the molecule. The A in the formula represents the central atom, the X represents the number of bonding pairs, and the E represents the number of unpaired electron pairs. For example SF4 would have a VSEPR formula of AX4E because the ...
by Louis Zhao 4C
Sun Nov 18, 2018 5:37 pm
Forum: Hybridization
Topic: Sigma and Pi Bonds [ENDORSED]
Replies: 12
Views: 118

Re: Sigma and Pi Bonds [ENDORSED]

Does anyone know the reason why pi bonds cannot rotate while sigma bonds can, so like how does the structure of each bond result in their ability to rotate?
by Louis Zhao 4C
Sun Nov 18, 2018 5:29 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge of Central Atom
Replies: 4
Views: 57

Re: Formal Charge of Central Atom

The formal charge of the Cl atom in ClO2+ can be +1 because the net charge of the all of the atoms should equal the net charge of the polyatomic ion which is +1 in this case. If both of the Cl-O bonds are double bonds then the two oxygen atoms have a formal charge of zero, and the formal charge of t...
by Louis Zhao 4C
Sat Nov 17, 2018 11:19 pm
Forum: Ionic & Covalent Bonds
Topic: Determining the Difference between Ionic and Covalent Bonds
Replies: 6
Views: 80

Re: Determining the Difference between Ionic and Covalent Bonds

When determining the difference between an ionic bond and a covalent bond, you first should look at the various elements in the molecule/compound in question. A molecule (covalent bonds) usually is between two nonmetals while a compound(ionic bonds) is usually between a metal and a nonmetal. However...
by Louis Zhao 4C
Sun Nov 11, 2018 9:19 pm
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonds
Replies: 1
Views: 24

Hydrogen Bonds

Why do different types of Hydrogen bonds have different bond energies. For example, why does a hydrogen bond between hydrogen and fluorine have a higher bond energy than a hydrogen bond between hydrogen and nitrogen. (F-----H—F) vs. (N-----H—N)
by Louis Zhao 4C
Sun Nov 11, 2018 9:11 pm
Forum: Lewis Structures
Topic: VSEPR Model
Replies: 1
Views: 25

Re: VSEPR Model

The geometry of molecules is formatted so that the electrons within the molecule have the least amount of repulsion possible. Repulsion strength is determined by looking at state of the electrons. Electrons that are lone pairs have the most repulsion so two lone pairs should be drawn on opposite sid...
by Louis Zhao 4C
Sun Nov 11, 2018 9:00 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 1
Views: 56

Re: Bond lengths

It depends on the possible resonance structures and the proportions of single bonds to double bonds. For example if there is one single bond and one double bond in a molecule, such as NO2-, the bond length would be around the average of the two. ((130nm(double bond) +150nm(single bond))/2) = 140nm. ...
by Louis Zhao 4C
Sat Nov 03, 2018 9:42 pm
Forum: Quantum Numbers and The H-Atom
Topic: Determining Amount of Electrons From Quantum Numbers
Replies: 4
Views: 50

Re: Determining Amount of Electrons From Quantum Numbers

The principal quantum number n determines the shell where the electrons are located, and the angular momentum quantum number l describes the shape (s, p, d, f). l can be any value from 0 to n-1. Therefore if we are asked how many electrons are in n=3 and l=2, we first try and determine which subshel...
by Louis Zhao 4C
Sat Nov 03, 2018 9:33 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 6
Views: 88

Re: Atomic Radius

Atomic radius increases across a period because the additional electrons being added are all in the same shell while at the same time we are adding protons to the nucleus. As we add more protons to the nucleus, the effective nuclear charge pulls the electron closer towards the nucleus. However, each...
by Louis Zhao 4C
Sat Nov 03, 2018 9:25 pm
Forum: Properties of Light
Topic: Practice Midterm 8b
Replies: 3
Views: 84

Re: Practice Midterm 8b

In the midterm review today, Lyndon used the work function equation : E(photon) - Threshold energy = E(kinetic energy) E(photon) = Plank constant(h)*frequency(v), threshold energy/work function is given, and E(kinetic energy) = 1/2(MV^2) where M is the mass of the electron and V is the velocity of t...
by Louis Zhao 4C
Sun Oct 28, 2018 5:38 pm
Forum: Student Social/Study Group
Topic: Studying for tests/midterm
Replies: 18
Views: 764

Re: Studying for tests/midterm

Do you guys know when/where these peer learning sessions usually are? Is there a schedule for them?
by Louis Zhao 4C
Sun Oct 28, 2018 5:34 pm
Forum: Ionic & Covalent Bonds
Topic: Polyatomic Ions [ENDORSED]
Replies: 4
Views: 73

Polyatomic Ions [ENDORSED]

Do we need to memorize the chemical formulas for common polyatomic ions such as Ammonium, Carbonate, Nitrate etc. or will their chemical formulas be given to us whenever they come up on a quiz or test.
by Louis Zhao 4C
Sun Oct 28, 2018 5:28 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7047
Views: 772980

Re: Post All Chemistry Jokes Here

A covalent bond yells at an ionic bond, "Didn't anybody ever teach you how to share?"
by Louis Zhao 4C
Sun Oct 21, 2018 8:17 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Hw Question 2.25
Replies: 1
Views: 24

Re: Hw Question 2.25

a. Since its in the p orbital, there are 6 electrons
b. since its in the d orbital, there are 10 electrons
c. Since its in the s orbital, there are 2 electrons
d. Since its in the f orbitals, there are 14 electrons
by Louis Zhao 4C
Sun Oct 21, 2018 6:59 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Px. Py, Pz
Replies: 6
Views: 94

Re: Px. Py, Pz

The Px, Py, Pz variables represent the 3 different electron cloud configurations in the p orbital of an atom. In relation Schrodinger's Wave Function, they are determined by the Ml value which range from -1 to 1. A -1 Ml value equals Px, 0 equals to Py, and 1 equals to Pz. i.e. the example Dr. Lavel...
by Louis Zhao 4C
Sun Oct 21, 2018 6:40 pm
Forum: Quantum Numbers and The H-Atom
Topic: Electron Shielding
Replies: 2
Views: 23

Electron Shielding

Can someone explain to me what electron shielding is and why electrons further away from the nucleus is less attractive.
by Louis Zhao 4C
Sun Oct 14, 2018 11:52 am
Forum: Einstein Equation
Topic: Test #2
Replies: 4
Views: 80

Re: Test #2

The Test Schedule on the website says Test #2 will be given starting October 23, which are the discussions of week 4.
by Louis Zhao 4C
Sun Oct 14, 2018 11:47 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Friday Lecture Example Question
Replies: 1
Views: 24

Friday Lecture Example Question

For the first example we did in class on Friday, why did we plug in a positive value into v= (E/h) when the calculated change in energy was a negative value.
by Louis Zhao 4C
Sun Oct 14, 2018 11:42 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: n Quantum Number
Replies: 1
Views: 45

Re: n Quantum Number

Because the n in the empirical equation for energy in hydrogen atoms (E =-hR/n^2) is in the denominator and is squared, the change in energy between each subsequent energy level decreases at an exponential rate.. Although the actual difference between each energy level gets closer and closer to zero...
by Louis Zhao 4C
Sun Oct 07, 2018 8:32 pm
Forum: Administrative Questions and Class Announcements
Topic: Number of questions on test one [ENDORSED]
Replies: 39
Views: 16740

Re: Number of questions on test one [ENDORSED]

Is the test format multiple choice, free response or a mixture of both?
by Louis Zhao 4C
Sun Oct 07, 2018 8:18 pm
Forum: Empirical & Molecular Formulas
Topic: Chemical Formula Element Order
Replies: 5
Views: 120

Re: Chemical Formula Element Order

I think the general consensus is that the atoms with lower electronegativity values are written first. So Osmium has the lowest electronegativity of 2.0, compared to Carbon (2.6) and Oxygen(3.4) so it would make sense to write it first. However, I don't think the order of elements in a chemical form...
by Louis Zhao 4C
Sun Oct 07, 2018 8:03 pm
Forum: Significant Figures
Topic: Sig Figs in the Middle of a Problem
Replies: 8
Views: 189

Sig Figs in the Middle of a Problem

Does anyone know if we should follow sig fig rules in the middle of a problem or only round to the nearest significant digit once you get the final answer.

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