Search found 104 matches

by Naji Sarsam 1F
Thu Mar 12, 2020 2:14 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7951
Views: 1123087

Re: Post All Chemistry Jokes Here

As my last post for chemistry community ever:

Never trust an atom...

I've heard they make up everything...
by Naji Sarsam 1F
Thu Mar 12, 2020 2:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: liquid mercury
Replies: 3
Views: 21

liquid mercury

I was studying electrochemistry and saw that for a galvanic cell, liquid mercury can act as an electrode. How is this possible?
by Naji Sarsam 1F
Thu Mar 12, 2020 1:54 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: translational and rotational contribution from molecular motion
Replies: 3
Views: 17

Re: translational and rotational contribution from molecular motion

The effect of translational and rotational momentum is covered in the chemistry textbook, however it is not of extreme importance. It is mainly used to derive the equations for the energy of ideal monoatomic gasses.
by Naji Sarsam 1F
Thu Mar 12, 2020 1:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L5. B)
Replies: 2
Views: 20

Re: 6L5. B)

I believe its because solid iodine cant be a conducting solid. It is a very brittle solid as it is not held together by ionic bonds but rather covalent bonds and intermolecular forces. Metals or Ionic solids can be electrodes, however.
by Naji Sarsam 1F
Thu Mar 12, 2020 1:05 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate of the reverse reaction
Replies: 3
Views: 22

Rate of the reverse reaction

Why can we ignore the rate of the reversion reaction when doing kinetics? Do the rate laws, such as rate = K [R1] [R2], give just the initial rate of the reaction or the rate of the reaction as it progresses?
by Naji Sarsam 1F
Sun Mar 08, 2020 2:04 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding carbon (gr) to cell diagrams
Replies: 4
Views: 22

Re: Adding carbon (gr) to cell diagrams

As far as I understand it, Carbon Graphite is just another alternative to platinum. Whenever you can use platinum you can also use carbon graphite. But as you said, platinum is much more common.
by Naji Sarsam 1F
Sun Mar 08, 2020 2:03 pm
Forum: General Science Questions
Topic: Review Packet
Replies: 14
Views: 95

Re: Review Packet

There have been no announcements yet about a review packet. I would imagine though that it would be announced in Monday's lecture if there is one. If not, then there probably isn't.
by Naji Sarsam 1F
Sun Mar 08, 2020 2:01 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Study Advice
Replies: 73
Views: 3411

Re: Study Advice

Also, If your schedule does not align with any review sessions, reading the assigned chapters in the book helps a lot. I know it takes quite a long time; you don't have to read everything, just what you need help on. OFten the book explains concepts very clearly and gives step by step problems.
by Naji Sarsam 1F
Sun Mar 08, 2020 1:59 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: concentration cells
Replies: 5
Views: 30

Re: concentration cells

To clarify, the reaction is still considered a redox reaction. However, it is also important to note that the standard cell potential of every concentration cell equals 0.
by Naji Sarsam 1F
Sun Mar 08, 2020 1:56 pm
Forum: General Rate Laws
Topic: Instantaneous and average reaction rate
Replies: 4
Views: 28

Re: Instantaneous and average reaction rate

The rate laws are instantaneous rates. Usually, the average rate won't be asked for unless the give you a chart of data.
by Naji Sarsam 1F
Sun Mar 01, 2020 11:53 pm
Forum: General Rate Laws
Topic: class notes
Replies: 2
Views: 31

Re: class notes

Often, chemical reactions may be understood as a series of reactions acting in order of steps to take the original reactants to create the final products. This series of steps is called the reaction mechanism. The slowest step of the reaction mechanism often determines the order of the reaction.
by Naji Sarsam 1F
Sun Mar 01, 2020 11:49 pm
Forum: Zero Order Reactions
Topic: order of reactions
Replies: 4
Views: 38

Re: order of reactions

Normally, the order of the reaction must be determined empirically. Often, empirical data is given in the question which you may manipulate to determine the order of the reaction.
by Naji Sarsam 1F
Sun Mar 01, 2020 11:47 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: observing initial rates
Replies: 3
Views: 37

Re: observing initial rates

This is because by definition, initial rates refer to the rate of the forward reaction at the moment it has started. Mathematically, this is when t approaches 0.
by Naji Sarsam 1F
Sun Mar 01, 2020 11:46 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in Equation
Replies: 6
Views: 40

Re: n in Equation

n represents the moles of electrons transferred in a redox reaction. To know how many electrons are transferred, you have to divide a redox reaction into its reduction and oxidation half-reactions.
by Naji Sarsam 1F
Sun Mar 01, 2020 11:44 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Standard E of concentration cell
Replies: 1
Views: 22

Re: Standard E of concentration cell

This is because since technically it is the same product and reactant on both sides. Thus the reduction reaction and oxidation reaction have equal magnitude yet opposite sign values for E. Thus when you add them together, they cancel out to equal 0.
by Naji Sarsam 1F
Sun Feb 23, 2020 10:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 4
Views: 27

Platinum

Can someone explain why platinum was used in the galvanic cell during dr. lavelle's lecture?
by Naji Sarsam 1F
Sun Feb 23, 2020 10:08 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Cell Potential intensive property
Replies: 2
Views: 21

Cell Potential intensive property

If cell potential is an intensive property, why does changing the molarity of reagents in a chemical reaction change the cell potential? In lecture we started using principles similar to le chatelier's principle, however, I thought cell potential does not matter on the amount of reagent present
by Naji Sarsam 1F
Sun Feb 23, 2020 9:59 pm
Forum: Student Social/Study Group
Topic: Friday lecture 02/21
Replies: 3
Views: 43

Re: Friday lecture 02/21

We discussed how three concepts.

1.) how to balance a redox reaction by splitting it into its composite half-reactions and then adding them together

2.) cell diagram notation

3.) the nernst equation
by Naji Sarsam 1F
Sun Feb 23, 2020 9:50 pm
Forum: Van't Hoff Equation
Topic: Constants in Van’t Hoff Equation [ENDORSED]
Replies: 4
Views: 51

Re: Constants in Van’t Hoff Equation [ENDORSED]

Yes, delta S and delta H are assumed to not be temperature-dependent, meaning constant, when using the vant hoff equation
by Naji Sarsam 1F
Sun Feb 23, 2020 9:48 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst
Replies: 7
Views: 53

Re: Nernst

The Nernst is E=E^{o}-\frac{RT}{nF}ln(Q) E is the cell potential of a reaction not at equilibrium and not at standard conditions E^{o} is the cell potential at standard conditions R is the gas constant T is the temperature of the reaction n is the moles reacting F is faradays constant Q is t...
by Naji Sarsam 1F
Tue Feb 18, 2020 1:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Nerves
Replies: 7
Views: 69

Re: Midterm Nerves

A good way to approach problems are to explicitly write down the variables that are given to you. For example, if a problem mentions 6 moles, 278.15 K temperature, and that it is an ideal gas then you should write down n = 6, T = 278.15, and R. Then write down the symbol for the variable(s) you are ...
by Naji Sarsam 1F
Tue Feb 18, 2020 1:43 pm
Forum: Van't Hoff Equation
Topic: Constant delta H
Replies: 4
Views: 26

Re: Constant delta H

Yes, the Vant Hoff equation can only be applied effectively under the assumption that the entropy change is independent of the temperature of the reaction. This assumption can be made unless explicitly told otherwise.
by Naji Sarsam 1F
Tue Feb 18, 2020 1:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Van't Hoff Equation
Replies: 4
Views: 29

Re: Van't Hoff Equation

The Van't Hoff Equation is derived from two expressions for Gibbs Free Energy.
by Naji Sarsam 1F
Tue Feb 18, 2020 1:41 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Midterm: Cp,m and Cv,m
Replies: 3
Views: 56

Re: Midterm: Cp,m and Cv,m

An easy way to remember all of the Cp,m values is the equation Cp,m = Cv,m + R. This equation is derived in the chemistry book chapter 4, and it lets you only have to memorize the Cv,m for monoatomic, linear, and nonlinear gasses since the Cp,m is just R plus those values.
by Naji Sarsam 1F
Tue Feb 18, 2020 1:38 pm
Forum: Balancing Redox Reactions
Topic: Balancing and Adding together Half-Rxns
Replies: 6
Views: 30

Re: Balancing and Adding together Half-Rxns

Moreover, chemical reactions are not known to just spontaneously release electrons. First, it is favorable for electrons to be bound to a nucleus since the positive nucleus attracts the negative electron. Second, the products of a chemical reaction require the same amount of electrons as the reactants
by Naji Sarsam 1F
Sun Feb 09, 2020 1:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: set up of equation
Replies: 1
Views: 23

Re: set up of equation

It does matter as the reaction is not in equilibrium yet, so you must know which side is the reactants and which side is the products because only the reactants will decrease and only the products will increase. The language of the question should inform you which side of the reaction is reactants o...
by Naji Sarsam 1F
Sun Feb 09, 2020 1:29 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Entropy units
Replies: 7
Views: 65

Re: Entropy units

The units for entropy and enthalpy may be joules or kilojoules, it is just whatever is most useful for the number of joules there are. However, when doing calculations that include entropy and enthalpy in an equation, of course, you must match up their units--most of the time to joules.
by Naji Sarsam 1F
Sun Feb 09, 2020 1:27 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Spontaneous vs Favorable
Replies: 8
Views: 46

Re: Spontaneous vs Favorable

There is no difference between the terms spontaneous and favorable in terms of chemical reactions. The formal term is actually spontaneous, but modern connotations of that word may make it seem that spontaneous reactions happen very quickly. Rather, the term means that the reaction is favorable and ...
by Naji Sarsam 1F
Sun Feb 09, 2020 1:25 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Gas Expansion
Replies: 3
Views: 31

Re: Gas Expansion

Dr. Lavelle's lecture pertained specifically to isothermic reversible expansion. In this type of expansion, the delta U equals 0. This is because isothermal reactions mean that once energy is used in the form of work, the system gains that energy back as heat to maintain the same temperature--thus t...
by Naji Sarsam 1F
Sun Feb 09, 2020 1:22 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Entropy Changes for Phase Changes
Replies: 1
Views: 16

Re: Entropy Changes for Phase Changes

A phase change affects the entropy of a molecule because intermolecular bonds are either being broken or formed, which affect how ordered the system is. In cases where intermolecular bonds are being broken--melting and boiling--the entropy increases as atoms are freer to move and occupy more energy ...
by Naji Sarsam 1F
Tue Feb 04, 2020 2:49 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Microstates
Replies: 5
Views: 25

Re: Microstates

If there are two possible options for a microstate, then W = 2^N where N is the number of atoms
by Naji Sarsam 1F
Tue Feb 04, 2020 2:48 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Microstates
Replies: 5
Views: 25

Re: Microstates

If there are two possible options for a microstate, then W = 2^N where N is the number of atoms
by Naji Sarsam 1F
Tue Feb 04, 2020 2:44 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Relation between Entropy and Enthalpy
Replies: 1
Views: 25

Re: Relation between Entropy and Enthalpy

An easy way to conceptualize it is as follows. When you heat up a substance, you give the atoms of that substance more energy. That means those atoms have more positions to be in as well as more energy states to be in. Thus, when you heat up a substance, you increase the Degeneracy W of the substanc...
by Naji Sarsam 1F
Tue Feb 04, 2020 2:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Thermochemistry vs Thermodynamics
Replies: 2
Views: 18

Re: Thermochemistry vs Thermodynamics

Thermodynamics is the study of heat exchange, work, and energy in general. Thermochemistry is a branch of thermodynamics that applies those concepts to specific chemical reactions. For example, bond-enthalpy is a thermochemistry concept as it applies the thermodynamic concept of energy to chemical b...
by Naji Sarsam 1F
Tue Feb 04, 2020 2:39 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Reversible Isothermic Reaction
Replies: 1
Views: 10

Re: Reversible Isothermic Reaction

Understanding this reaction is difficult because of vague terminology. The set up of this reaction is such that the system does not lose any net energy, meaning there is no net change in temperature. What happens is when the gas expands it does work. This work, of course, requires energy, which is d...
by Naji Sarsam 1F
Tue Feb 04, 2020 2:33 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Equation
Replies: 2
Views: 15

Re: Equation

As far as Dr. Lavelle has used it in lecture, he only used it in a theoretical sense--not in actual application. Lavelle used this equation to prove that the internal energy U of an isothermal reversible reaction is 0. This is because the temperature is constant for this reaction, and as the equatio...
by Naji Sarsam 1F
Sun Jan 26, 2020 8:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpies of Formation
Replies: 4
Views: 18

Re: Standard Enthalpies of Formation

Standard enthalpies of formation are given for certain molecules in the tables of the textbook. The standard enthalpy of a reaction though should be calculated.
by Naji Sarsam 1F
Sun Jan 26, 2020 8:54 pm
Forum: Phase Changes & Related Calculations
Topic: Class Lecture to Textbook
Replies: 2
Views: 45

Re: Class Lecture to Textbook

We discussed section 4C i believe
by Naji Sarsam 1F
Sun Jan 26, 2020 8:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond vs Standard Enthalpies
Replies: 1
Views: 23

Re: Bond vs Standard Enthalpies

Bond Enthalpies refer to the energy stored in a certain type of bond--whether it be single, double, or triple--and the specific atoms that are being bonded Standard Enthalpies of Formation refer to the energy stored in a molecule calculated from the reaction of its formation from the most stable for...
by Naji Sarsam 1F
Sun Jan 26, 2020 8:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard enthalpy of formation of pure elements?
Replies: 1
Views: 9

Re: Standard enthalpy of formation of pure elements?

The standard enthalpy of formation by definition refers to the energy of the reaction required to produce a molecule from the most stable states of its constituent atoms. For example, the reaction for the stand enthalpy of formation for Hydrogen Iodide is: H_{2} + I_{2} \rightarrow 2HI The standard ...
by Naji Sarsam 1F
Sun Jan 26, 2020 8:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure & temperature in chemical equilibria
Replies: 3
Views: 21

Re: Pressure & temperature in chemical equilibria

To understand how temperature affects a reaction, one must know whether the reaction is endothermic or exothermic. For temperature increases: Products are favored in endothermic reactions Reactants are favored in exothermic reactions For temperature decreases: Reactants are favored in endothermic re...
by Naji Sarsam 1F
Mon Jan 20, 2020 12:35 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5% Rule
Replies: 6
Views: 30

Re: 5% Rule

Yes. Moreover, it is important to understand that chemical equilibria and acid-base equilibria are the same exact process. We just have different terms for the Ks of each as acid-base reactions usually involve just proton disassociation. Thus, almost everything you would do for chemical equilibria a...
by Naji Sarsam 1F
Mon Jan 20, 2020 12:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Delta G
Replies: 2
Views: 12

Re: Delta G

Dr. Lavelle said that Delta G will not be on this exam. He was referencing future material for those who may remember enthalpy from highschool chemistry.
by Naji Sarsam 1F
Mon Jan 20, 2020 12:32 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: buffers
Replies: 2
Views: 29

Re: buffers

Yes, this material will be on Test 1
by Naji Sarsam 1F
Mon Jan 20, 2020 12:27 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Halogens
Replies: 2
Views: 47

Re: Halogens

Halogen anions in solution do not affect the ph as they are weak conjugate bases of their corresponding strong acids: HCl, HBr, Hi, and so on. The only exception to this would be F- anion, as it is a strong conjugate base since HF is a weak acid.
by Naji Sarsam 1F
Mon Jan 20, 2020 12:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6E Polyprotic Acids and Bases
Replies: 2
Views: 29

Re: 6E Polyprotic Acids and Bases

A polyprotic acid is an acid that can disassociate more than once. An example of this is phosphoric acid. However, it requires much less energy for this acid to disassociate the first time in comparison to the energy required to disassociate the second or third time. Thus, regarding the Ka of each d...
by Naji Sarsam 1F
Fri Jan 10, 2020 2:33 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Why Q would be greater than K
Replies: 5
Views: 27

Re: Why Q would be greater than K

That is correct. Reactions at equilibrium do not naturally stray from equilibrium. That does not only mean that Q would ever increase to higher than K once at equilibrium, but also that it would never decrease lower than K.
by Naji Sarsam 1F
Fri Jan 10, 2020 11:45 am
Forum: Ideal Gases
Topic: Chatelier’s Principle
Replies: 8
Views: 61

Chatelier’s Principle

Can someone please explain how Le Chatelier’s Principle works? especially with changes in pressure?
by Naji Sarsam 1F
Fri Jan 10, 2020 11:40 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and relation of [R] to [P]
Replies: 5
Views: 52

Re: Q and relation of [R] to [P]

To understand how a reaction will proceed to reach equilibrium, it is important to understand what K and Q represent symbolically. Both represent the ratio of products to reactants in the reaction. However, K represents that ratio at equilibrium, while Q represents that ratio while not at equilibriu...
by Naji Sarsam 1F
Fri Jan 10, 2020 11:22 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K for Heterogeneous Equilibria
Replies: 4
Views: 23

Re: K for Heterogeneous Equilibria

For heterogeneous equilibrium problems, it may be confusing as to use either concentrations or pressure. But recognize, if there are any reactants which are aqueous, it does not make sense to use their partial pressure. Thus, you’d have to use concentration for all reagents in the equilibrium. If th...
by Naji Sarsam 1F
Fri Jan 10, 2020 11:18 am
Forum: Administrative Questions and Class Announcements
Topic: Peer Learning
Replies: 4
Views: 31

Re: Peer Learning

Peer Learning Sessions are opportunities Dr. Lavelle Provides for students who are either confused on a subject or just need extra help. There are three types of sessions: drop-in sessions, workshops, and step-up sessions.
by Naji Sarsam 1F
Sat Dec 07, 2019 5:59 pm
Forum: Lewis Acids & Bases
Topic: Lewis vs Bronsted
Replies: 3
Views: 19

Re: Lewis vs Bronsted

Yes, an example is ammonia NH3

All bronsted acids are also lewis acids, but not all lewis acids are bronsted acids.
by Naji Sarsam 1F
Sat Dec 07, 2019 5:58 pm
Forum: Coordinate Covalent Bonds
Topic: Just to clear it up
Replies: 1
Views: 42

Re: Just to clear it up

Yes, all ligands in coordinate compounds are lewis bases because they donate electrons. The central metal atom then is a lewis acid
by Naji Sarsam 1F
Sat Dec 07, 2019 5:56 pm
Forum: Amphoteric Compounds
Topic: Amphoteric vs Amphiprotic
Replies: 11
Views: 114

Re: Amphoteric vs Amphiprotic

The difference between amphoteric and amphiprotic lies in understanding the difference between lewis acids and bronsted acids. Bronsted acids require a proton to be donated or accepted. The lewis acid definition encompasses all bronsted acids, but also acids which do not donate protons but rather ju...
by Naji Sarsam 1F
Sat Dec 07, 2019 5:51 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Conjugate Seesaw
Replies: 2
Views: 24

Re: Conjugate Seesaw

I believe you are misundestanind what the conjugate see saw is. The conjugate seesaw refers to the foloowing four concepts 1.) if an acid is strong, the conjugate base is weak 2.) if an acid is weak, the conjugate base is strong 3.) if an base is strong, the conjugate acid is weak 4.) if an base is ...
by Naji Sarsam 1F
Sat Dec 07, 2019 5:48 pm
Forum: Biological Examples
Topic: Final
Replies: 6
Views: 87

Re: Final

The hydrogen bonding od DNA Base pairs, heme as a coordination compound, cisplatin for chemotherapy, vitamins as acceptors of dangerous radicals, the role of carbon dioxide in blood ph

These are the examples i can think of
by Naji Sarsam 1F
Mon Dec 02, 2019 12:43 pm
Forum: Hybridization
Topic: Key aspect of hybridization
Replies: 1
Views: 25

Re: Key aspect of hybridization

Hybridization is when a central atom's orbitals average in their energy levels, creating hybrid orbitals to free up all of their electrons. I think the simplest example demonstrating this is Carbon. Carbon has an electron ground state of [He] 2s^{2} 2p^{2} This means that carbon only has two unpaire...
by Naji Sarsam 1F
Mon Dec 02, 2019 11:48 am
Forum: Naming
Topic: Non-anionic ligands
Replies: 2
Views: 41

Re: Non-anionic ligands

It is possible to have positively charged ligands, although they are rare because ligands are lewis bases. The charge of the ligand does not matter in naming, but the charge of the central transition metal does matter. So if the positively charged ligand means that the central transition metal has a...
by Naji Sarsam 1F
Mon Dec 02, 2019 11:38 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ferrocene
Replies: 1
Views: 30

Re: Ferrocene

Yes the Iron is bonded to the carbon on each side of the "sandwhich"
by Naji Sarsam 1F
Mon Dec 02, 2019 11:34 am
Forum: Conjugate Acids & Bases
Topic: Naming
Replies: 4
Views: 58

Re: Naming

There are different naming conventions for different types of molecules. Here are the very basic rules Ions: "Cation Name" "Anion Name + ide" ex.) NaCl : Sodium Cholride Covalently Bonded Molecules: "Central Atom's Name" "Greek Suffix + Peripheral Atom's Name + ide...
by Naji Sarsam 1F
Sun Nov 24, 2019 11:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR formula
Replies: 5
Views: 27

Re: VSEPR formula

You do not need to do any mathematical calculations to determine angles. Rather you have to memorize the angles present in each molecular geometry, and that every time a bonding pair of electrons is replaced by a lone pair, those angles decrease. Linear molecules have an angle of 180 Tetrahedral mol...
by Naji Sarsam 1F
Sun Nov 24, 2019 11:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape of carbon Dioxide
Replies: 10
Views: 48

Re: Molecular shape of carbon Dioxide

The molecular geometry of carbon dioxide is linear. This is because there are only two electron density regions: the two double bonds between carbon and each atom.
by Naji Sarsam 1F
Sun Nov 24, 2019 11:51 pm
Forum: Hybridization
Topic: Sigma and Pi bonds
Replies: 3
Views: 22

Re: Sigma and Pi bonds

Sigma bonds are stronger than pi bonds because the electron clouds between atoms that have a sigma bond overlap more than those electron clouds would overlap in a pi bond. The more overlap between electron clouds in sigma bonds allows for a stronger electronegative attraction between shared electron...
by Naji Sarsam 1F
Sun Nov 24, 2019 11:48 pm
Forum: Hybridization
Topic: Sigma and Pi Bonds
Replies: 21
Views: 97

Re: Sigma and Pi Bonds

There are two characteristics of bonds that we need to know: the number of bonds and the type of bonds. The number of bonds refers to whether it is a single, double, or triple bond. The type of bond refers to whether the bond is a sigma or pi bond. A sigma bond is one where the electron clouds overl...
by Naji Sarsam 1F
Sun Nov 24, 2019 11:42 pm
Forum: Hybridization
Topic: unused orbitals
Replies: 4
Views: 31

Re: unused orbitals

It can stay a p orbital, as there is the hybridization sp2 which is used in molecular geometries with three regions of electron density--such as trigonal planar geometries.
by Naji Sarsam 1F
Sun Nov 24, 2019 11:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: t shape and see saw
Replies: 6
Views: 34

Re: t shape and see saw

Molecular geometries depend on the number of atoms bonded to the central atom, and the number of lone pairs that central atom has. Molecules which have 5 atoms bonded to the central atom, and 0 lone pairs, are of the geometry trigonal bipyramidal. Molecules which have 4 atoms bonded to the central a...
by Naji Sarsam 1F
Sun Nov 17, 2019 1:42 pm
Forum: Sigma & Pi Bonds
Topic: Test 2 Sigma and Pi bonds
Replies: 5
Views: 46

Re: Test 2 Sigma and Pi bonds

Yes, sigma and pi bonds will be on the exam. Dr. Lavelle discussed them very shortly at the end of Friday's lecture on 11/15/19. He will discuss them more on the upcoming Monday lecture on 11/18/19. Briefly: single bonds have a sigma bond; double bonds have one sigma bond and one pi bond; triple bon...
by Naji Sarsam 1F
Sun Nov 17, 2019 1:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral??
Replies: 4
Views: 30

Re: Octahedral??

This is the same as tetrahedrals. They are not called tetrahedrals because the molecule has four atoms, rather it is the mathematical term for the shape with 4 equal faces. It just happens that 4 atoms arrange themselves into the vertices of the tetrahedral
by Naji Sarsam 1F
Sun Nov 17, 2019 1:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral??
Replies: 4
Views: 30

Re: Octahedral??

The name octahedral refers to the shape that a six atom molecule makes. This is because the term is a geometric one, as octahedral refers to the geometric shape hacing 8 faces, thus octa. However, the shape only has 6 vertices, which in a molecule is the 6 atoms.
by Naji Sarsam 1F
Sun Nov 17, 2019 1:33 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: This Week Test
Replies: 12
Views: 85

Re: This Week Test

Yes, this exam should also include intermolecular forces as well as the VSEPR model. Moreover, the first slide of Dr. Lavelle's lecture on Monday 11/18/19 will be on the exam. However, Dr. Lavelle noted that hybridization will not be on the exam.
by Naji Sarsam 1F
Sun Nov 17, 2019 1:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Strength of Repulsion
Replies: 4
Views: 30

Re: Strength of Repulsion

This is because lone pair electrons take up more volume with their electron clouds as they are only being held by one atom's nucleus. Bonding electrons are confined to a smaller volume as they feel the influence of two atoms' nuclei, confining them to a smaller space. Thus, it is not that lone pair ...
by Naji Sarsam 1F
Sun Nov 17, 2019 1:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Interactions
Replies: 3
Views: 25

Re: Interactions

Yes, that is the correct order of interaction strength, except that it is missing the ion-ion interaction which is the strongest interaction of all. And yes, Van Der Waal Forces also are called London Forces. However, Dr. Lavelle prefers if you call the interaction induced dipole-induced dipole inte...
by Naji Sarsam 1F
Sun Nov 10, 2019 9:08 pm
Forum: Dipole Moments
Topic: Dipole-Induced Dipole
Replies: 2
Views: 18

Re: Dipole-Induced Dipole

dipole - induced dipole interaction: One molecule has a permanent dipole This permanent dipole molecule is near another molecule that doesn't have a permanent dipole However, the molecule with a permanent dipole polarizes the other molecule, inducing a dipole in it, and forming an intermolecular int...
by Naji Sarsam 1F
Sun Nov 10, 2019 9:00 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polarizability v. polar power
Replies: 1
Views: 17

Re: polarizability v. polar power

It is important to distinguish between polarizing power and polarizability. Polarizing power is the ability of an atom to polarize another. Polarizability is the opposite: the ability of an atom to be polarized. Polarizability is similar to the trend of electronegativity. An atom is more polarizable...
by Naji Sarsam 1F
Sun Nov 10, 2019 8:59 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: Interaction Potential Energy
Replies: 1
Views: 17

Re: Interaction Potential Energy

Interaction potential energy is always negative because atoms always lose energy when forming bonds; they never gain energy. In other words, the energy of an atom without a bond is higher than that of the same atom with a bond. So, if you take the final energy of the atom with the bond and subtract ...
by Naji Sarsam 1F
Sun Nov 10, 2019 8:55 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: Hydrocarbons at room temperature
Replies: 2
Views: 17

Re: Hydrocarbons at room temperature

The length and shape of a hydrocarbon often affect its state of matter when at room temperature. When hydrocarbons have the same shape--particularly the rod shape--the longer hydrocarbons are those that are more solid while the shorter ones are more liquid and gaseous. When hydrocarbons have the sam...
by Naji Sarsam 1F
Sun Nov 10, 2019 8:45 pm
Forum: Bond Lengths & Energies
Topic: Interaction Potential Energy
Replies: 1
Views: 23

Re: Interaction Potential Energy

Interaction potential energy is always negative because atoms always lose energy when forming bonds; they never gain energy. In other words, the energy of an atom without a bond is higher than that of the same atom with a bond. So, if you take the final energy of the atom with the bond and subtract ...
by Naji Sarsam 1F
Sun Nov 10, 2019 8:42 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: Polarizability
Replies: 3
Views: 19

Re: Polarizability

It is important to distinguish between polarizing power and polarizability. Polarizing power is the ability of an atom to polarize another. Polarizability is the opposite: the ability of an atom to be polarized. Polarizability is similar to the trend of electronegativity. An atom is more polarizable...
by Naji Sarsam 1F
Sun Nov 10, 2019 8:30 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: Fluctuating Dipoles
Replies: 5
Views: 35

Re: Fluctuating Dipoles

Fluctuating dipoles becomes important when discussing induced dipole - induced dipole interactions. A simplification of the premise is that electrons in an atom are always moving; they are not static. Thus, in molecules, electrons are still moving around their atoms in, essentially, random motion. T...
by Naji Sarsam 1F
Sun Nov 03, 2019 10:01 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 3
Views: 39

Re: Drawing Lewis Structures

Here it is important to understand the difference between formal charge and charge. The charge relates to the entire molecule. For example the charge of H_{2}O is 0; the charge of the sulfate polyatomic ion is 2-. The formal charge then is a calculation tool used for single atoms in particular withi...
by Naji Sarsam 1F
Sun Nov 03, 2019 9:54 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Visualizing orbitals
Replies: 1
Views: 32

Re: Visualizing orbitals

The square of the atomic orbital function gives the probability of where the electron will be in that orbital.

So the orbital function describes the shape of the volume the electron can reside; the square of that function tells you how likely it is to be in each location within that volume.
by Naji Sarsam 1F
Sun Nov 03, 2019 9:51 pm
Forum: Octet Exceptions
Topic: Uhhh
Replies: 3
Views: 51

Re: Uhhh

There are two kinds of octet exceptions: atoms which exceed the octet and those which fall short of an octet. The atoms which exceed the octet are those in columns 15 through 17 and in rows 3 or below. The most common we will use are Phosphorus, Sulfur, and Chlorine. This is because these atoms can ...
by Naji Sarsam 1F
Sun Nov 03, 2019 9:43 pm
Forum: Lewis Structures
Topic: Showing work for valence electrons
Replies: 3
Views: 28

Re: Showing work for valence electrons

It may just be helpful to quickly show the addition of valence electrons to show the calculation for the total number of valence electrons. It will help you keep track and also make it easier for the grader.
by Naji Sarsam 1F
Sun Nov 03, 2019 9:41 pm
Forum: Lewis Structures
Topic: "Most favorable" Diagram
Replies: 4
Views: 34

Re: "Most favorable" Diagram

When the question asks to draw the "most favorable" lewis structure, it generally means just the correct one if it doesn't have resonance. However, in some cases, a molecule can have resonance where one structure is preferred over another. This has to do with the formal charge. With some m...
by Naji Sarsam 1F
Sun Nov 03, 2019 9:37 pm
Forum: Bond Lengths & Energies
Topic: Bond Strength and Electronegativity
Replies: 3
Views: 26

Re: Bond Strength and Electronegativity

The relationship between bond strength and electronegativity is an indirect one to understand: 1.) Electronegativity refers to the tendency of an atom to attract and accept an electron. 2.) A bond is when two atoms share at least a pair of electrons. Bond strength is affected by two principles: the ...
by Naji Sarsam 1F
Sat Oct 26, 2019 2:45 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum number m
Replies: 3
Views: 30

Re: Quantum number m

There are four quantum numbers: n, l, m_{l} , and m_{s} These four quantum numbers explain the individual properties of every electron possible in an atom. Moreover, in one atom, two electrons cannot have the same values for all four quantum numbers. Pertaining to the quantum number "m", t...
by Naji Sarsam 1F
Sat Oct 26, 2019 2:36 pm
Forum: Trends in The Periodic Table
Topic: Electronegativity vs Electron Affinity
Replies: 6
Views: 44

Re: Electronegativity vs Electron Affinity

Electron affinity and electronegativity describe similar processes in different ways. Electron affinity is the energy released when an atom--in the gaseous phase--gains an electron This energy can be directly measured Electronegativity is the "ability" of an atom to attract electrons This ...
by Naji Sarsam 1F
Sat Oct 26, 2019 2:15 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Special elements
Replies: 2
Views: 22

Re: Special elements

There are two exceptions: Chromium: Which should be [Ar] 3d^{4} 4d^{2} according to the systematic pattern normally used However, it is actually [Ar] 3d^{5} 4d^{1} Copper Which should be [Ar] 3d^{9} 4d^{2} according to the systematic pattern normally used However, it is actually [Ar] 3d^{10} 4d^{1} ...
by Naji Sarsam 1F
Sat Oct 26, 2019 2:10 pm
Forum: Lewis Structures
Topic: Shape of bonds?
Replies: 2
Views: 34

Re: Shape of bonds?

We will be discussing the shape of molecules (the VSEPR model) in a future lecture. As of week 4, we have not discussed this and thus you should not be worried about the three-dimensional structure of molecules.
by Naji Sarsam 1F
Sat Oct 26, 2019 2:07 pm
Forum: Photoelectric Effect
Topic: Rydberg Formula
Replies: 1
Views: 49

Re: Rydberg Formula

The Rydberg Formula Dr. Lavelle taught us is E_{n}=-\frac{hR}{n^{2}} This equation gives us the energy of an electron at a particular energy level ( E_{n} ) given that we know the energy level the electron is at (n), the plank constant (h) and the Rydberg constant (R). Thus, the solution of this equ...
by Naji Sarsam 1F
Sat Oct 19, 2019 12:19 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration of Tungsten (W) compared to Chromium (Cr) [ENDORSED]
Replies: 2
Views: 179

Re: Electron configuration of Tungsten (W) compared to Chromium (Cr) [ENDORSED]

The reason for Tungsten not following the exception rule that Chromium does is not needed for our course. We only need to know the electron configurations for the first row of the d block, since this is a life science chemistry course.
by Naji Sarsam 1F
Sat Oct 19, 2019 12:11 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: building up principle
Replies: 5
Views: 37

Re: building up principle

Dr. Lavelle mentioned two exceptions in class to the Aufbau principle: Chromium and Copper. Could someone please explain what those exceptions are and why they are there?
by Naji Sarsam 1F
Sat Oct 19, 2019 12:08 pm
Forum: Properties of Light
Topic: Quantum equations
Replies: 5
Views: 39

Re: Quantum equations

In all of the equations used for the Quantum Mechanics unit, distance must be converted to meters. After a calculation is done, the problem may ask for a unit different than meters, such as Angstrom or nanometers. Only convert to these units after the calculation is complete, never before.
by Naji Sarsam 1F
Sat Oct 19, 2019 12:03 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: HW 1B.27
Replies: 2
Views: 24

Re: HW 1B.27

In an uncertainty problem where they give a "variable" ± "a value", the uncertainty is twice that "value". This is easier to understand by example: If a problem describes the velocity of an object as 5.00 m/s ± 1.00, the uncertainty would be double the value of 1.00, eq...
by Naji Sarsam 1F
Sat Oct 19, 2019 11:49 am
Forum: *Shrodinger Equation
Topic: Concepts of Schrodinger equation
Replies: 3
Views: 35

Re: Concepts of Schrodinger equation

An extra note which is important to keep in mind is that the "Wave Function" is a mathematical equation. That is why it is also called the Schrodinger Equation. Once you think of it in that way, it becomes very easy to contextualize all of the chemistry terms related to it. We will not lea...
by Naji Sarsam 1F
Sat Oct 12, 2019 10:31 am
Forum: Properties of Electrons
Topic: De Broglie Problems
Replies: 4
Views: 44

Re: De Broglie Problems

Aa Dr. Lavelle discussed in class, traditionally, wavelengths smaller than 10 ^ -15 meters are considered to have unmeasurable wave-like properties. Instead, they would only have particle-like properties.
by Naji Sarsam 1F
Sat Oct 12, 2019 10:29 am
Forum: Properties of Light
Topic: Circular Standing Waves and electrons
Replies: 2
Views: 44

Re: Circular Standing Waves and electrons

The wave model of electrons properly predicts energy levels if electrons are modeled as circular standing waves around the nucleus. This is because all waves--circular or not--have differing energies. However, for a circular standing wave to exist, it must be continuous and have no discontinuities s...
by Naji Sarsam 1F
Sat Oct 12, 2019 10:23 am
Forum: Einstein Equation
Topic: Diffraction patterns
Replies: 2
Views: 47

Re: Diffraction patterns

To understand diffraction patterns, one must first recognize that there are two models possible for understanding the motion of an object relevant to chemistry: the particle model and the wave model. The particle model interprets objects as solid objects which have a defined location in space. The w...
by Naji Sarsam 1F
Sat Oct 12, 2019 10:14 am
Forum: Photoelectric Effect
Topic: Energy classification
Replies: 2
Views: 20

Re: Energy classification

Yes, this energy is called by two names: "threshold energy" and the "work function". The reason for this energy being called the "threshold energy" is because that is the exact energy that marks the boundary for an atom to eject its electron or not. At the threshold ene...
by Naji Sarsam 1F
Thu Oct 03, 2019 8:50 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Formula Units
Replies: 6
Views: 84

Re: Formula Units

Formula units are different from molecules in that all atoms in an ionic compound have formed atomic bonds with other atoms, to form a lattice. In this way, ionic compounds are not groups of moleculas which are associeated with one another through intermolecular bonds. Rather, they are one coherent ...

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