Search found 87 matches

by Junwei Sun 4I
Thu Jan 23, 2020 12:20 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H20 in the ICE table
Replies: 26
Views: 76

Re: H20 in the ICE table

In an ICE table we leave about liquids and solids. If the H2O is in gas phase then it will be included in the ICE table as well.
by Junwei Sun 4I
Thu Jan 23, 2020 12:18 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic vs. Endothermic reactions
Replies: 8
Views: 21

Re: Exothermic vs. Endothermic reactions

It is possible in the context of the Le Chatelier's principle. For example how will the equilibrium shift if temperature is increased/decreased given a reaction is endothermic or exothermic.
by Junwei Sun 4I
Thu Jan 23, 2020 12:15 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 Practice Worksheet #5
Replies: 5
Views: 69

Re: Test 1 Practice Worksheet #5

I got 8.62 too maybe you forget to convert pKa to pKb since C6H7O2-(aq) is a base. And you first calculate pOH and then subtract and get the pH value.
by Junwei Sun 4I
Thu Jan 23, 2020 12:09 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acidity Constant
Replies: 4
Views: 15

Re: Acidity Constant

Ka x Kb equals a constant Kw at 25 degree Celsius. Therefore a big Ka value would imply a small Kb value.
by Junwei Sun 4I
Thu Jan 23, 2020 12:06 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% rule
Replies: 13
Views: 25

5% rule

When do we use the 5% rule? Do we only use it in acid and base equilibrium questions or any equilibrium questions?
by Junwei Sun 4I
Fri Jan 17, 2020 12:51 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic
Replies: 5
Views: 16

Re: Exothermic

Molecules tend to be in the lowest energy state to be the most stable. When a bond is formed the molecules become more stable, therefore heat is released so the molecules' energy lowered. Whereas when breaking a bond the molecules become more unstable, which means it is not in its lowest energy state.
by Junwei Sun 4I
Fri Jan 17, 2020 12:47 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Solids and Liquids in Le Chatelier
Replies: 5
Views: 17

Re: Solids and Liquids in Le Chatelier

No removing or adding a solid or liquid would not affect the equilibrium since they are not included in the equilibrium expression K.
by Junwei Sun 4I
Thu Jan 16, 2020 7:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Bar and atm
Replies: 1
Views: 9

Bar and atm

When we are writing out the equilibrium expression Kp should the partial pressures always be in bar? If given atm do we have to covert that to bar and then calculate Kp?
by Junwei Sun 4I
Mon Jan 13, 2020 12:37 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Increase pressure by half the volume
Replies: 3
Views: 13

Increase pressure by half the volume

How will the equilibrium shift if pressure is increased by halting the volume?
by Junwei Sun 4I
Mon Jan 13, 2020 12:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solid and Liquid
Replies: 5
Views: 23

Solid and Liquid

Why is it that when we write the expression for K we don't include solid and liquid? Is it because their concentration does not change or is it that the change is insignificant? Also for solid and liquid do we always write them as 1 in the equilibrium expression?
by Junwei Sun 4I
Thu Jan 09, 2020 11:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 5H.1 Part 1
Replies: 4
Views: 20

Re: Textbook 5H.1 Part 1

We get the square root of 41 because the stoichiometric coefficients of all molecules in the original equation are all multiplied by 1/2. Therefore we get the value of the new K by taking the square root of the original K value.
by Junwei Sun 4I
Thu Jan 09, 2020 11:42 pm
Forum: Ideal Gases
Topic: Solving for K (coefficients)
Replies: 11
Views: 37

Re: Solving for K (coefficients)

The coefficients become the power of the molar concentrations in the expression for K and they have to be assigned to the specific molecules as they are in the chemical equation. For example in H2 + I2 --> 2HI,

[H2] and [I2] will have a power of 1
[HI] will have a power of 2
by Junwei Sun 4I
Thu Jan 09, 2020 11:37 pm
Forum: Ideal Gases
Topic: 5G1 true/false
Replies: 8
Views: 41

Re: 5G1 true/false

This statement is false since even if you start with a higher pressure of reactants, this would only result in production of more products and in the end the equilibrium constant remains the same.The value of K is not affected by the addition of products and reactants as long as the temperature is t...
by Junwei Sun 4I
Thu Jan 09, 2020 11:34 pm
Forum: Ideal Gases
Topic: Reaction Quotient (Q)
Replies: 8
Views: 27

Re: Reaction Quotient (Q)

The reaction quotient Q is calculated in the same way with K using the same expression. However the difference is that when you look for Q the concentration/partial pressure values you plugged in are not yet at equilibrium. Reaction quotient Q is important since we can use it to determine which way ...
by Junwei Sun 4I
Thu Jan 09, 2020 11:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Q Values
Replies: 5
Views: 22

Re: K and Q Values

When Q>K, more reactants will tend to be formed so the reaction can reach equilibrium. The reverse reaction in this case is favored.
by Junwei Sun 4I
Thu Dec 05, 2019 5:23 pm
Forum: Identifying Acidic & Basic Salts
Topic: Acid protonation
Replies: 4
Views: 29

Re: Acid protonation

505106414 wrote:What exactly is protonation? What is happening to an acid undergoing protonation?


Protonation is the process in which a proton H+ is added to an atom, ion, or molecule and form a conjugate acid.An acid undergoing protonation gets a proton.
by Junwei Sun 4I
Thu Dec 05, 2019 5:21 pm
Forum: Identifying Acidic & Basic Salts
Topic: Acid protonation
Replies: 4
Views: 29

Re: Acid protonation

The acid gets protonated when pH of the solution is smaller than the acid's pKa value. If pH<pKa, it implies that the solution is more acidic than the acid. In this case the solution will act like an acid and donate a proton. This proton will be picked up by the pKa acid and it will be protonated. I...
by Junwei Sun 4I
Thu Dec 05, 2019 5:14 pm
Forum: Identifying Acidic & Basic Salts
Topic: Names of Acids and Bases
Replies: 3
Views: 52

Re: Names of Acids and Bases

I don't think we need to know them but I will do it just in case it shows up.
by Junwei Sun 4I
Thu Dec 05, 2019 5:13 pm
Forum: Identifying Acidic & Basic Salts
Topic: Salt
Replies: 5
Views: 33

Re: Salt

It depends on the salt you have. For example, NaCl will not affect the pH of water because it is a neutral salt. However, NH4Cl will lower the pH of water because NH4+ make water acidic.
by Junwei Sun 4I
Thu Dec 05, 2019 5:09 pm
Forum: Identifying Acidic & Basic Salts
Topic: Lecture
Replies: 3
Views: 25

Re: Lecture

Cl- ion does not affect pH of water because it is a stable ion. It will not tend to bind to hydrogen atoms in water because itself is already stable. Therefore it will not cause any change in pH. And typically group one and group two cations metals are neutral.
by Junwei Sun 4I
Thu Dec 05, 2019 4:34 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 6C.21 B)
Replies: 1
Views: 23

6C.21 B)

6C.21 B) asks whether CH3COOH or HCOOH is a stronger acid. How can you tell? I know the solution manual says that -CH3 group has electron donating properties but why is that? Thank you.
by Junwei Sun 4I
Thu Dec 05, 2019 4:10 pm
Forum: Bronsted Acids & Bases
Topic: 6C.19
Replies: 1
Views: 12

6C.19

Homework question 6C.19 d) asks whether HClO4 or H3PO4 is a stronger acid. How can we tell? Thanks.
by Junwei Sun 4I
Wed Nov 27, 2019 10:17 pm
Forum: Bronsted Acids & Bases
Topic: Relative Acidity
Replies: 1
Views: 15

Relative Acidity

Why does delocalized electrons imply stable anions? In other words why is the anion stabilized by electron withdrawing atoms?
by Junwei Sun 4I
Wed Nov 27, 2019 10:12 pm
Forum: Conjugate Acids & Bases
Topic: strength of an acid and its conjugate base
Replies: 3
Views: 21

Re: strength of an acid and its conjugate base

Yes this is true. Conjugate base of a strong acid will be a weak base. Conjugate base of a weak acid will be a strong base. The stronger the acid/base, the weaker its conjugate base/acid, and vice versa.
by Junwei Sun 4I
Wed Nov 27, 2019 10:10 pm
Forum: Lewis Acids & Bases
Topic: Lewis acid vs regular acid?
Replies: 4
Views: 22

Re: Lewis acid vs regular acid?

They are talking about the same thing. Lewis acid is just one of the definitions of acids. All acids can be said in two different definitions, which are bronsted definition and lewis definition.In bronsted definition the acts is the proton(H+) donor, and in lewis definition the acid is the electron ...
by Junwei Sun 4I
Wed Nov 27, 2019 10:07 pm
Forum: Lewis Acids & Bases
Topic: Proton acceptor and proton donor?
Replies: 33
Views: 133

Re: Proton acceptor and proton donor?

Acids are the proton donor and bases are the proton acceptor (Bronsted definition).
by Junwei Sun 4I
Mon Nov 25, 2019 8:26 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Prefixes
Replies: 1
Views: 32

Prefixes

In homework problem 9C.3 there's a complex name containing "bisoxalato." What's the difference between using bi-, tri-, tetra- and using bis-, tris-, and tetrakis- and when do we use each set of prefixes? Thanks!
by Junwei Sun 4I
Mon Nov 25, 2019 8:20 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Question on naming coordinate compound
Replies: 2
Views: 27

Question on naming coordinate compound

In the textbook it writes iron as "ferrate" in the complex with an overall negative charge. For example hexacyanidoferrate(II) ion. I'm just curious if there is such thing as "ironate" or it is a rule to write iron as "ferrate" when we are naming a complex with overall ...
by Junwei Sun 4I
Fri Nov 22, 2019 10:38 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: transition metals
Replies: 3
Views: 23

Re: transition metals

Transition metals having many oxidation states make them good for electron transfer.
by Junwei Sun 4I
Fri Nov 22, 2019 10:36 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating Ligands
Replies: 2
Views: 32

Re: Chelating Ligands

According to my notes, a chelate complex is a complex containing ligands that form a ring of atoms that include the central metal atom. Chelating ligands can bind cations really tightly, therefore such complexes such as EDTA, is good at removing metals from solution because the metal ion is bounded ...
by Junwei Sun 4I
Fri Nov 22, 2019 10:29 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Sphere
Replies: 6
Views: 33

Re: Coordination Sphere

Ligands directly attacked to central ion make up the coordinate sphere.
by Junwei Sun 4I
Thu Nov 21, 2019 10:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: NH3 replaces H20 ligands
Replies: 2
Views: 16

NH3 replaces H20 ligands

In class Dr. Lavelle talked about transition metal cations in solution form complex with H20, and when NH3 or K+CN- are added those species will replace the H20 ligands. Why does that happen and how? Thanks!
by Junwei Sun 4I
Thu Nov 21, 2019 10:33 pm
Forum: Biological Examples
Topic: Cisplatin
Replies: 4
Views: 47

Re: Cisplatin

Basically cisplatin forms a coordinate compound with the DNA strands by binding its two Chlorine atoms to DNA. Since there are two places that are bounded cisplatin bounds to DNA really tightly. When cell division happens cisplatin blocked the enzyme from going through, therefore stopping DNA replic...
by Junwei Sun 4I
Thu Nov 21, 2019 10:29 pm
Forum: Hybridization
Topic: lone pairs in hybridization
Replies: 8
Views: 36

Re: lone pairs in hybridization

Yes lone pairs are counted as areas of electron density just like the bounding electrons.
by Junwei Sun 4I
Fri Nov 15, 2019 4:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: varying VSEPRs
Replies: 7
Views: 43

Re: varying VSEPRs

No the shape does not vary. Just like resonance structures does not matter in VSEPR model.
by Junwei Sun 4I
Fri Nov 15, 2019 4:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: vsepr formula
Replies: 3
Views: 30

Re: vsepr formula

A represent the central atom.
X represents the bonded atoms.
E represents the lone pairs.

For example if you have NH3 you got central atom N with three atoms bonded to it and one lone pair, therefore the notation should be AX3E.
by Junwei Sun 4I
Fri Nov 15, 2019 4:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How to tell polar or non polar from lewis structure?
Replies: 9
Views: 59

How to tell polar or non polar from lewis structure?

Could someone please clarify how we can tell if a molecule is polar or non-polar from looking at its lewis structure? What are some factors in a lewis structure that will make a molecule polar?
by Junwei Sun 4I
Fri Nov 15, 2019 4:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: why are double bonds equally weighted as single ones when drawing models?
Replies: 10
Views: 58

Re: why are double bonds equally weighted as single ones when drawing models?

VSEPR model only takes in consideration of region of electron density. Therefore having a double bond or a single bond indicate the same, one region of electron density.
by Junwei Sun 4I
Fri Nov 15, 2019 4:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 6
Views: 53

Re: Bond Angles

I agree with the above posts of doing more practice problems.Also if you remember the repulsion strength order in which lone pair - lone pair repulsion is bigger than lone pair - bonding pair repulsion is bigger than bonding pair - bonding pair repulsion it also helps. Since when you draw out the le...
by Junwei Sun 4I
Fri Nov 15, 2019 4:03 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: nonpolar molecules
Replies: 5
Views: 31

Re: nonpolar molecules

All non-polar molecules have London Dispersion forces but be careful sometimes in the presence of a polar molecule they can also have dipole-induced dipole forces.
by Junwei Sun 4I
Fri Nov 15, 2019 4:00 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Why does SO2 molecules have dipole-dipole interations?
Replies: 4
Views: 19

Re: Why does SO2 molecules have dipole-dipole interations?

SO2 molecules have dipole-dipole interactions because they are polar. When drawing out the lewis structure for SO2 the central atom S has one lone pair, which means it's polar.
by Junwei Sun 4I
Thu Nov 07, 2019 11:06 pm
Forum: Dipole Moments
Topic: Ionic bonds
Replies: 5
Views: 28

Re: Ionic bonds

Yes dipole moments can happen in ionic bonds. For example when there's an obvious difference in electronegativity between ions there can be dipole moments.
by Junwei Sun 4I
Thu Nov 07, 2019 11:05 pm
Forum: Dipole Moments
Topic: Explain concept
Replies: 4
Views: 31

Re: Explain concept

A dipole moment basically occurs whenever there is a distinction between negative and positive charge. When in a chemical bond atom on one side of the bond has more negative charge than atom on the other side, we can say there's a dipole moment, since there is a separation of the positive and negati...
by Junwei Sun 4I
Thu Nov 07, 2019 10:49 pm
Forum: Octet Exceptions
Topic: Why can't Aluminum have an expanded octet?
Replies: 5
Views: 63

Re: Why can't Aluminum have an expanded octet?

Aluminum does not have an expanded octet. Aluminum is an exception just like boron where it can be octet deficient. Just like in BF3 boron is stable with only six electrons, in AlCl3 aluminum also does not fill an octet.
by Junwei Sun 4I
Thu Nov 07, 2019 10:44 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: 2D.5 - Electronegativity
Replies: 4
Views: 56

Re: 2D.5 - Electronegativity

It will be more clear to look at the actual electronegativity value but in this case you can also look at their position on the periodic table and predict the electronegativity difference with periodic trend. C and S are located really close to each other, so it is reasonable to assume they have sim...
by Junwei Sun 4I
Thu Nov 07, 2019 10:40 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarisability vs Polarizing Power
Replies: 15
Views: 110

Re: Polarisability vs Polarizing Power

Polarizing power normally indicates the ability of the cation to attract the valence electrons of an anion, which is the ability of an atom to cause electron cloud distortion. Whereas polarizability means the atom's ability/tendency to be polarized, in order words the atom's ability to form dipoles....
by Junwei Sun 4I
Thu Nov 07, 2019 10:33 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Strength of Cations
Replies: 8
Views: 46

Re: Polarizing Strength of Cations

Because if the size of the cation is smaller, the closer the distance between the cation's nucleus with the electrons, which means the electrons will experience a higher attraction force from the cation's nuclear charge. As a result, electrons are more likely to be pulled towards this small size cat...
by Junwei Sun 4I
Thu Nov 07, 2019 10:28 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Distorted e- as highly polarizable
Replies: 5
Views: 49

Re: Distorted e- as highly polarizable

Highly distorted electrons are described as highly polarizable because they are more likely to cause dipoles. As electrons are pulled toward one side of the ions they are really likely to create dipole since the charge now is uneven. The more the number of distorted electrons being pulled into the b...
by Junwei Sun 4I
Thu Nov 07, 2019 10:18 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: HW 2D.3
Replies: 5
Views: 66

Re: HW 2D.3

BaBr2 is more ionic compare to BeBr2 and BBr3 because the electronegativity difference between Ba-Br is the greatest compares to electronegativity difference between Be-Br and B-Br. Electronegativity increases across the period and decreases down the group. Therefore the electronegativity difference...
by Junwei Sun 4I
Fri Nov 01, 2019 10:04 pm
Forum: Electronegativity
Topic: Electronegativity in Lewis Structure
Replies: 2
Views: 23

Electronegativity in Lewis Structure

Do atoms that are more electronegative always the central atom in a lewis structure? In order words does the central atom of a lewis structure always has the highest electronegativity compare to the other atoms in the structure?
by Junwei Sun 4I
Fri Nov 01, 2019 10:01 pm
Forum: Electronegativity
Topic: Electron Negativity vs affinity?
Replies: 5
Views: 29

Re: Electron Negativity vs affinity?

Electronegativity indicates HOW WELL/TENDENCY an atom attracts electrons to itself. Whereas electron affinity measures the exact amount of energy released when an electron is added to an atom in the gas phase.
by Junwei Sun 4I
Fri Nov 01, 2019 9:59 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 11
Views: 54

Re: Electronegativity

Electronegativity indicates how well an atom attracts electrons to itself. It increases across the period since atomic radius decreases across the period. With valence electrons being closer to the nucleus they experience more attraction forces. Therefore the atom attracts electrons better. Electron...
by Junwei Sun 4I
Fri Nov 01, 2019 9:56 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Central atom
Replies: 8
Views: 82

Re: Central atom

Formal charge of the central atom is not always zero. It is better to look at formal charges of all atoms inside a structure. With more atoms having a formal charge of zero the structure is the most stable. And in the case when the formal charges are not zero, the more electronegative atom should ha...
by Junwei Sun 4I
Fri Nov 01, 2019 9:53 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charges
Replies: 4
Views: 29

Re: Formal Charges

Formal charge for the same atom in resonance structures should be the same. For example in SO4 2-, when you draw out the lewis structure you get S as the central atom with two Os attached to it by double bonds and two Os attached to it by single bonds. No matter how you orientate the double bonds in...
by Junwei Sun 4I
Fri Nov 01, 2019 9:27 pm
Forum: Octet Exceptions
Topic: radical
Replies: 5
Views: 59

Re: radical

Radicals are simply compounds with unpaired electrons. Radicals are exception of the octet rule because a radical might not have a filled octet with 8 electrons. For example Dr. Lavelle talked about CH3 in class. When we draw out the lewis structure for CH3, the central atom C have 7 valence electro...
by Junwei Sun 4I
Fri Nov 01, 2019 9:23 pm
Forum: Resonance Structures
Topic: Resonance Hybrid
Replies: 2
Views: 23

Re: Resonance Hybrid

Yes it is necessary. It's always good to draw all the resonance structures since the actual structure of the molecule is the average of all the resonance structures.
by Junwei Sun 4I
Fri Nov 01, 2019 9:22 pm
Forum: Lewis Structures
Topic: Exceptions to the Octet
Replies: 5
Views: 37

Re: Exceptions to the Octet

Phosphorous violates the octet rule since it can have an expanded octet. P is in the third period on the periodic table, which means it has d-orbital that can accommodate extra electrons.For example when P bonds with Cl forming PCl5, the central atom P would have a total of 10 electrons, which viola...
by Junwei Sun 4I
Thu Oct 24, 2019 8:58 pm
Forum: Lewis Structures
Topic: Where to start putting dots for electrons
Replies: 10
Views: 73

Re: Where to start putting dots for electrons

There are no specific rules on where to start putting dots but when dots are put around an atom it has to reflect whether the electrons are paired or not. Therefore when you put dots around an atom you always put four separate dots on four sides first.
by Junwei Sun 4I
Thu Oct 24, 2019 8:55 pm
Forum: Ionic & Covalent Bonds
Topic: octet rule
Replies: 6
Views: 89

Re: octet rule

Yes besides H, He, Li and Be there are other exceptions to the octet rule. For example boron. When boron bounds with three fluorine atoms boron only gets six electrons instead of eight. And there's also something called expanded octet, which is when a central atom in a lewis structure can have more ...
by Junwei Sun 4I
Thu Oct 24, 2019 8:46 pm
Forum: Ionic & Covalent Bonds
Topic: strength of bonds
Replies: 11
Views: 106

Re: strength of bonds

PranaviKolla3G wrote:In terms of electrons, what is the difference between a triple bond, a double bond, and a single bond?


Triple bonds represent three pairs of electrons. Double bonds represent two pairs of electrons. Single bonds represent one pair of electrons.
by Junwei Sun 4I
Thu Oct 24, 2019 8:44 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic v.covalent bonds
Replies: 7
Views: 40

Re: Ionic v.covalent bonds

Your understanding is correct. Basically ionic bonds are formed between metals are nonmetals, and covalent bonds are formed between nonmetals and nonmetals. In an ionic bond electrons are transferred and ions are formed. In a covalent bond electrons are shared.
by Junwei Sun 4I
Thu Oct 24, 2019 8:26 pm
Forum: Lewis Structures
Topic: chemical formulas
Replies: 3
Views: 47

Re: chemical formulas

It's always good to know the commonly known compounds but I think when you are asked to draw the lewis structures the formulas will be given.
by Junwei Sun 4I
Thu Oct 24, 2019 8:24 pm
Forum: Ionic & Covalent Bonds
Topic: strength of bonds
Replies: 11
Views: 106

Re: strength of bonds

Triple bonds are shorter than double bonds because there are more attraction forces and they tend to be stronger. Double bonds are shorter and stronger than single bonds because of the same reason.
by Junwei Sun 4I
Thu Oct 24, 2019 8:15 pm
Forum: Ionic & Covalent Bonds
Topic: electron configuration for ions
Replies: 3
Views: 70

Re: electron configuration for ions

Because electrons are removed from the highest energy level first. When electrons are filled in 3d orbitals, 4s orbital has higher energy than 3d. Therefore when electrons are removed electrons from higher energy level are removed first. That's why Ni2+ has ground-state electron configuration of [Ar...
by Junwei Sun 4I
Thu Oct 17, 2019 11:14 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 7
Views: 60

Re: Nodal Planes

Nodal planes are the regions where there is zero probability density (zero probability of finding an e-). And for s-orbital there is no nodal plane. For p-orbital there are 1. D-orbital has 2 and f-orbital has 3. And I think you can relate this to the angular momentum quantum number. S has an angula...
by Junwei Sun 4I
Thu Oct 17, 2019 11:09 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: electron position
Replies: 3
Views: 22

Re: electron position

You can not determine the precise location of an electron because it acts like a wave and you can't localize a wave. At one point the electron might be at one location and the next instant it will be somewhere else, and there's pattern in this movement. Kind of imagine playing a guitar and the elect...
by Junwei Sun 4I
Thu Oct 17, 2019 11:03 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Incorrect Atom Model
Replies: 3
Views: 29

Re: Incorrect Atom Model

When you apply the Heisenberg's equation to the incorrect atomic model, we get the result that the uncertainty in electrons' velocity is greater than the speed of light, which is unrealistic. Therefore this atomic model must be wrong and electrons do not located in the nucleus and are not confined t...
by Junwei Sun 4I
Thu Oct 17, 2019 10:59 pm
Forum: *Shrodinger Equation
Topic: Nodal Planes
Replies: 6
Views: 30

Re: Nodal Planes

f orbitals have 3 nodal planes and I think the number of nodal planes an orbital has is equal to its angular momentum quantum number, such that s orbital has no nodal plane; p orbitals have 1; d orbitals have 2 and f orbitals have 3.
by Junwei Sun 4I
Thu Oct 17, 2019 10:57 pm
Forum: Quantum Numbers and The H-Atom
Topic: spin up and spin down
Replies: 7
Views: 39

Re: spin up and spin down

The numbers are only arbitrary and we only need to focus on whether the electron is spinning upward or downward. The value +- 1/2 don't really mean any specific values in electron spinning.
by Junwei Sun 4I
Thu Oct 17, 2019 10:54 pm
Forum: Quantum Numbers and The H-Atom
Topic: quantum number topic
Replies: 4
Views: 37

Re: quantum number topic

Quantum numbers in general characterize/specify an orbital. Quantum numbers can be looked at as a wave function which has a solution with n, l, ml. "n" determines energy, which means which shell the electrons are in. "l" describes shape of the orbital and can be [0,n-1]. l=0 corr...
by Junwei Sun 4I
Sat Oct 12, 2019 12:38 pm
Forum: Properties of Electrons
Topic: Wave properties
Replies: 5
Views: 34

Re: Wave properties

All matter has wave-like properties according to De Broglie's equation. Just like Dr. Lavelle said in class this equation defines that any moving object with momentum p has wavelike properties with a specific wavelength. However this wavelength can only be detected in moving objects with extremely s...
by Junwei Sun 4I
Sat Oct 12, 2019 12:33 pm
Forum: DeBroglie Equation
Topic: Definitions?
Replies: 2
Views: 29

Re: Definitions?

Momentum is measured as mass times velocity and in physics it can be looked at as the quantity of motion of a moving object. If an object has a mass and it is moving (in motion), then it will have momentum. According to p=mv, we can know that momentum is directly proportional to the object's mass an...
by Junwei Sun 4I
Sat Oct 12, 2019 12:28 pm
Forum: Einstein Equation
Topic: Diffraction Pattern
Replies: 3
Views: 35

Re: Diffraction Pattern

More specifically what does "in phase" and "out of phase" mean?
by Junwei Sun 4I
Sat Oct 12, 2019 12:25 pm
Forum: Properties of Electrons
Topic: Mass of Electron in De Broglie Equation
Replies: 4
Views: 31

Re: Mass of Electron in De Broglie Equation

I think Dr. Lavelle said numbers such as mass of an electron will be given to us on a formula sheet so no need to worry about that.
by Junwei Sun 4I
Sat Oct 12, 2019 12:20 pm
Forum: Einstein Equation
Topic: Diffraction Pattern
Replies: 3
Views: 35

Diffraction Pattern

Could someone please explain what are constructive interference and destructive interference? Thanks.
by Junwei Sun 4I
Wed Oct 09, 2019 10:35 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 4
Views: 50

Re: Speed of Light

Yes the constant ice used in class is only for the speed of light in vacuum. I assume we probably won't encounter any problem with light not in a vacuum and even if we do we'll probably be given more information.
by Junwei Sun 4I
Wed Oct 09, 2019 10:25 pm
Forum: Quantum Numbers and The H-Atom
Topic: Atomic Spectra
Replies: 5
Views: 45

Re: Atomic Spectra

Yes they should always be balanced as along as they are for the same atom.
by Junwei Sun 4I
Wed Oct 09, 2019 10:23 pm
Forum: Photoelectric Effect
Topic: Energy of Photon = Work Function
Replies: 4
Views: 56

Re: Energy of Photon = Work Function

When energy of the photo is equal to energy of the work function the electron will still get ejected since the energy of the photon reaches the threshold energy, which is the minimum amount of energy needed to remove an electron from the metal surface. I was confused at this concept too of ejected e...
by Junwei Sun 4I
Wed Oct 09, 2019 9:59 pm
Forum: Properties of Light
Topic: Work Function
Replies: 3
Views: 25

Re: Work Function

Work function just means the minimum amount of energy required to remove an electron from the surface of a metal. You can also look at it as the threshold energy. Once the energy of the photon exceeds the threshold energy the electron gets removed from the metal surface.
by Junwei Sun 4I
Sun Oct 06, 2019 11:50 pm
Forum: SI Units, Unit Conversions
Topic: Angstrom(Å)
Replies: 4
Views: 32

Re: Angstrom(Å)

I think angstrom is not recognized as an official SI unit.
by Junwei Sun 4I
Sun Oct 06, 2019 11:48 pm
Forum: Balancing Chemical Reactions
Topic: Naming/Polyatomic ions
Replies: 4
Views: 39

Re: Naming/Polyatomic ions

I don't think knowing polyatomic ions are required but it's always good to know them.
by Junwei Sun 4I
Sun Oct 06, 2019 11:40 pm
Forum: SI Units, Unit Conversions
Topic: Test 1
Replies: 9
Views: 132

Re: Test 1

Molarity and dilution will be on the test especially m1v1=m2v2 I think. And it will be good to know molarity = moles/volume.
by Junwei Sun 4I
Thu Oct 03, 2019 12:33 am
Forum: Limiting Reactant Calculations
Topic: M 15
Replies: 4
Views: 38

Re: M 15

Firstly you will need to convert grams to moles and check which reactant is the limiting reactant. Once you know the limiting reactant you should use the molar ratio and the balanced chemical equation to calculate the amount of aluminum chloride you will get(this is the theoretical yield.) Then use ...
by Junwei Sun 4I
Thu Oct 03, 2019 12:27 am
Forum: Balancing Chemical Reactions
Topic: Unequal coefficients
Replies: 7
Views: 68

Re: Unequal coefficients

Every chemical equation should be able to be balanced.Sometimes fractions do occur when you try to balance an equation for example in combustion reactions.When fractions do occur you can just multiply every coefficient by the common denominator of the fractions so that you will have whole number coe...
by Junwei Sun 4I
Thu Oct 03, 2019 12:21 am
Forum: Molarity, Solutions, Dilutions
Topic: M1V1=M2V2 [ENDORSED]
Replies: 3
Views: 44

Re: M1V1=M2V2 [ENDORSED]

M wouldn't cancel out here since M1V1 actually comes from manipulating the equation Molarity(M)=number of moles(n)/volume. Since we know that moles of solute remain the same when diluting a solution we manipulate M=n/v to be n=MV so that we could set up the equation M1V1=M2V2 to solve for unknowns i...
by Junwei Sun 4I
Thu Oct 03, 2019 12:14 am
Forum: Empirical & Molecular Formulas
Topic: Question about Theoretical Yield
Replies: 8
Views: 102

Re: Question about Theoretical Yield

You can always convert moles to grams and vice versa so they should be the same.Pay attention to units though especially when you are doing percent yield (which is equal to (actual yield/theoretical yield)*100%) since you'll want units for actual yield and theoretical yield to be the same in this ca...
by Junwei Sun 4I
Thu Oct 03, 2019 12:05 am
Forum: SI Units, Unit Conversions
Topic: Unit Conversions
Replies: 11
Views: 118

Re: Unit Conversions

You will need to use Avogadro's number which is 1 mole = 6.022*10^23 atoms. For example if you want to convert 12g of Na to atoms you will first need do 12g Na* (1 mole Na / 22.98g Na) which gives you the answer of 0.52 moles of Na. Then you calculate 0.52 moles Na * (6.022*10^23 atoms / 1 mole Na) ...

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