Search found 97 matches

by Louise Lin 2B
Sun Mar 08, 2020 3:16 pm
Forum: Second Order Reactions
Topic: Termolecular
Replies: 15
Views: 271

Re: Termolecular

termolecular would cause third order reactions, which is when three molecules collide a the exact same time in the exact very specific orientation to generate a reaction. the possibility of this is very low, so it is a rare occurrence
by Louise Lin 2B
Sun Mar 08, 2020 2:30 pm
Forum: First Order Reactions
Topic: rate constants
Replies: 19
Views: 104

Re: rate constants

yes rate constants are always positive because even when reactions slow down or reverse, the rate from product to reactant is still moving forward, making the rate constant positive.
by Louise Lin 2B
Sun Mar 08, 2020 2:18 pm
Forum: First Order Reactions
Topic: order of reaction equations
Replies: 6
Views: 59

Re: order of reaction equations

Although Dr. Lavelle does a lot of derivations in class, I believe he does them so we can see the correlations. I doubt we would be asked to derive the integrated rate law since practical application seems to be more the theme of his exams
by Louise Lin 2B
Sun Mar 08, 2020 2:10 pm
Forum: Zero Order Reactions
Topic: third order
Replies: 11
Views: 352

Re: third order

The third order is when three molecules collide at the same time and in a certain correct orientation that causes a reaction to take place.
by Louise Lin 2B
Sun Mar 08, 2020 2:07 pm
Forum: Zero Order Reactions
Topic: Not used Half life
Replies: 8
Views: 308

Re: Not used Half life

the half-life of a zero-order reaction actually depends on the initial concentration and the rate constant
by Louise Lin 2B
Sun Mar 01, 2020 6:25 pm
Forum: General Rate Laws
Topic: Reaction Rates
Replies: 5
Views: 47

Re: Reaction Rates

reaction rates are always positive because despite the possibility of reactions slowing down, it is nevertheless moving forward still.
by Louise Lin 2B
Sun Mar 01, 2020 5:37 pm
Forum: First Order Reactions
Topic: First Order Reaction Rate
Replies: 4
Views: 50

Re: First Order Reaction Rate

Adriana_4F wrote:Does anyone know if this will be on Test 2?

I believe that test 2 only goes up till electrochemistry, and rate laws are part of kinetics, so I don't think rate laws will be on test 2.
by Louise Lin 2B
Sun Mar 01, 2020 5:36 pm
Forum: First Order Reactions
Topic: Order of the Reaction
Replies: 2
Views: 35

Re: Order of the Reaction

the order of the reaction means that the rate is proportional to the concentration of types of molecules involved in the reaction. the reactants must collide simultaneously, with enough energy and the correct orientation to make a reaction happen.
by Louise Lin 2B
Sun Mar 01, 2020 4:11 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: how can you tell
Replies: 11
Views: 86

Re: how can you tell

reactions that quickly react usually mean that it is controlled more via kinetics, while reactions that are carried out more slowly suggest that they are being controlled more via thermodynamics. this is also the reason why the terms spontaneous and nonspontaneous might be misleading,
by Louise Lin 2B
Sun Mar 01, 2020 4:08 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: intermediate
Replies: 22
Views: 401

Re: intermediate

Intermediates ultimately get canceled out when you write out chemical equations in the full, so they will not show up in the rate law because only the initial reactants and final products have an influence on the rate law.
by Louise Lin 2B
Sun Feb 23, 2020 7:10 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: F
Replies: 7
Views: 40

Re: F

Faraday's constant is the charge in coulombs of 1 mole of electrons
by Louise Lin 2B
Sun Feb 23, 2020 7:08 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: how to get n in equation
Replies: 8
Views: 48

Re: how to get n in equation

the n in the NERNST equation is the number of electrons from the half reactions
by Louise Lin 2B
Sun Feb 23, 2020 6:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 4
Views: 25

Re: Platinum

to add on to the above responses, aside from platinum, another suitable solid inert substance is graphite.
by Louise Lin 2B
Sun Feb 23, 2020 6:34 pm
Forum: Balancing Redox Reactions
Topic: Flow of electrons
Replies: 11
Views: 50

Re: Flow of electrons

Yes; anodes are oxidized and cathodes are reduced. Thus the flow of electrons is from oxidized substances to reduced substances.
by Louise Lin 2B
Sun Feb 23, 2020 6:33 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox EQs
Replies: 10
Views: 75

Re: Balancing Redox EQs

the reaction depends on the molecules involved; if acidic, use H+ and if acidic, use OH-
by Louise Lin 2B
Mon Feb 17, 2020 3:24 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Signs for Gibbs Free Energy
Replies: 11
Views: 64

Re: Signs for Gibbs Free Energy

A negative deltaG means that the reaction is spontaneous, and usually exothermic. A positive delta G means that the reaction is nonspontaneous, and usually endothermic.
by Louise Lin 2B
Mon Feb 17, 2020 3:13 pm
Forum: Balancing Redox Reactions
Topic: Rules for oxidation numbers
Replies: 6
Views: 27

Re: Rules for oxidation numbers

ions have less or more electrons than the pure substance; thus their charge is never zero
by Louise Lin 2B
Mon Feb 17, 2020 2:35 pm
Forum: Balancing Redox Reactions
Topic: oxidation number
Replies: 10
Views: 47

Re: oxidation number

you can also find oxidation numbers in the context of the reactions, like when you write out the oxidation and reduction half-reactions
by Louise Lin 2B
Mon Feb 17, 2020 2:32 pm
Forum: Balancing Redox Reactions
Topic: Why do we split equations?
Replies: 12
Views: 50

Re: Why do we split equations?

Splitting the reactions allows you to see the intermediate molecules that would not be seen in the net reaction. Also, it allows you to identify the electron transfer more easily.
by Louise Lin 2B
Mon Feb 17, 2020 2:28 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Delta G
Replies: 6
Views: 46

Re: Delta G

also, delta G naught usually refers to the reaction in a laboratory setting, while delta G refers to reactions in a biological setting, like within the body.
by Louise Lin 2B
Sun Feb 09, 2020 11:51 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: Degrees of Change in Entropy
Replies: 5
Views: 28

Re: Degrees of Change in Entropy

also, to add on to the answers above, the degree symbol next to the delta variables indicate that they occur under lab conditions. without the degree symbol, the delta variables are typically in regards to biological conditions.
by Louise Lin 2B
Sun Feb 09, 2020 11:27 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Temp vs Vol
Replies: 3
Views: 29

Re: Temp vs Vol

Adding on to the previous answer, volume and pressure changes are temporary, so it will affect Q, but the reaction will always adjust to return to equilibrium K.
by Louise Lin 2B
Sun Feb 09, 2020 11:25 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs Free Energy
Replies: 2
Views: 29

Re: Gibbs Free Energy

There are still some cases that might differ! For example, imagine that the enthalpy value and the entropy value were both positive. If the value this would mean the (-TdeltaS) would be negative. However, if the value of enthalpy is higher than the value of -TdeltaS, overall Gibbs free energy would ...
by Louise Lin 2B
Sun Feb 09, 2020 11:23 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Entropy V.S Enthalpy QUestion
Replies: 3
Views: 26

Re: Entropy V.S Enthalpy QUestion

Not necessarily, spontaneous and nonspontaneous would have to depend on how large the values of entropy and enthalpy are compared to each other. For example, if both entropy and enthalpy were negative, it is still possible for the overall reaction to be nonspontaneous if the value of entropy multipl...
by Louise Lin 2B
Sun Feb 09, 2020 11:20 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Study Advice
Replies: 73
Views: 3409

Re: Study Advice

I really like going to Lyndon's workshops on Mondays, but to study I also rewrite my notes the day of the lecture (mainly because I have bad handwriting haha but it really helps), and doing the problems from the textbook! Also! study buddies are super helpful, even if it's just to help you stay focu...
by Louise Lin 2B
Sun Feb 02, 2020 5:16 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Changes Due to Temperature
Replies: 2
Views: 20

Entropy Changes Due to Temperature

For entropy changes due to temperature, does it vary depending on whether or not the reaction is exothermic or endothermic? I was thinking that increasing temperature for an endothermic reaction would actually decrease the entropy of the system...
by Louise Lin 2B
Sun Feb 02, 2020 5:06 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: entropy?
Replies: 4
Views: 29

Re: entropy?

entropy is the measure of disorder in a system. the more disorderly, the more (positive) the entropy and vice versa. disorder in a system also modifies energy, so it is important to include entropy when describing a system.
by Louise Lin 2B
Sun Feb 02, 2020 5:04 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Value of q
Replies: 11
Views: 76

Re: Value of q

in a perfect system, q(system)=-q(surroundings). if we apply this to the universe as a whole (surroundings), this would be true. besides that, there are no true perfect systems.
by Louise Lin 2B
Sun Feb 02, 2020 4:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard States
Replies: 2
Views: 12

Re: Standard States

standard states also mean that since the molecule/element is in its most stable form, it will not undergo a change that changes enthalpy. Therefore, enthalpy of standard state molecules/elements are zero.
by Louise Lin 2B
Sun Feb 02, 2020 4:51 pm
Forum: Phase Changes & Related Calculations
Topic: phase change from liquid to vapor
Replies: 8
Views: 61

Re: phase change from liquid to vapor

The more kJ/mol that the phase change takes, the more energy is released. A liquid burn does not have a phase change; it is merely the water that gets heated, but has not reached the point where enough energy changes the liquid into a gas. By contrast, a steam burn, upon contact with your skin, turn...
by Louise Lin 2B
Sun Jan 26, 2020 5:19 pm
Forum: Phase Changes & Related Calculations
Topic: State Properties
Replies: 3
Views: 10

Re: State Properties

Some examples of state properties are temperature, pressure, and volume.
by Louise Lin 2B
Sun Jan 26, 2020 5:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Types of Delta H
Replies: 3
Views: 24

Re: Types of Delta H

the unit for delta Hf is kJ/mol, but for delta Hc I believe that the units are kJ/C, in which C represents a unit uniform throughout the problem
by Louise Lin 2B
Sun Jan 26, 2020 5:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard enthalpy of solids and liquids
Replies: 2
Views: 16

Re: Standard enthalpy of solids and liquids

unless specified otherwise, the conditions in which the substances are in should usually use the standard enthalpies of formation
by Louise Lin 2B
Sun Jan 26, 2020 4:46 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard enthalpy of element in most stable form
Replies: 5
Views: 28

Re: Standard enthalpy of element in most stable form

from what I understand, the standard enthalpy of an element is dependent on the standard state that the element is typically found in. For example, oxygen is not typically found as just O, but it is found as O 2 . Thus, like a previous comment said above, the standard enthalpy of the element in its ...
by Louise Lin 2B
Sun Jan 26, 2020 4:38 pm
Forum: Phase Changes & Related Calculations
Topic: What is a state function?
Replies: 3
Views: 32

Re: What is a state function?

A state function describes the type of system the observed materials are in, and quantitatively describe the equilibrium state of said system.
by Louise Lin 2B
Sun Jan 19, 2020 9:55 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: temperature
Replies: 10
Views: 57

Re: temperature

Depending on if the reaction is exothermic or endothermic, temperature will change the equilibrium constant (K) of the reaction. Usually, unless a problem says otherwise, we can treat the reaction like it is at room temperature.
by Louise Lin 2B
Sun Jan 19, 2020 9:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs Q
Replies: 14
Views: 51

Re: K vs Q

K is appropriate to use when the reaction is already at equilibrium. There is only one K value for each reaction and its circumstances (temperature, pressure, etc.) Q is appropriate to use at any point in time of the reaction, and is used to compare to K.
by Louise Lin 2B
Sun Jan 19, 2020 9:50 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: X was ignored
Replies: 27
Views: 136

Re: X was ignored

the -x was ignored because the value is so small that it makes no difference to include it or not. This is called a small approximation.
by Louise Lin 2B
Sun Jan 19, 2020 9:41 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE Tables
Replies: 13
Views: 63

Re: ICE Tables

H2O isn't usually included because it is provided in excess in experiments, and is usually in liquid form. Liquid and solids are not supposed to be included in ICE tables.
by Louise Lin 2B
Sun Jan 19, 2020 7:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Acidity and Basicity
Replies: 4
Views: 40

Re: Acidity and Basicity

A high pH and a low pOH means that the resulting solution is basic. A low pH and a high pOH means that the resulting solution is acidic. pH and pOH values should add up to be 14.
by Louise Lin 2B
Fri Jan 10, 2020 9:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Le Chatelier's Principle
Replies: 7
Views: 49

Re: Le Chatelier's Principle

An example of Le Chatelier's would be to decrease the volume, and if there are more moles of gas on the left, then the reaction would shift to the right to accommodate for the change and vice versa.
by Louise Lin 2B
Fri Jan 10, 2020 5:18 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and speed of reaction
Replies: 5
Views: 37

Re: Q and speed of reaction

Q is only the constant calculated from the ratio between the products and reactants at some point in time during the reaction before it reaches equilibrium. It does not actually tell us the speed at which the reaction takes place.
by Louise Lin 2B
Fri Jan 10, 2020 5:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Catalysts
Replies: 7
Views: 41

Re: Catalysts

All of the above are correct, but also, as discussed in class, it's important to add that catalysts only speed up the reaction, but the ultimate yield of the concentration will be the same as letting the reaction proceed by itself. This means that catalysts only help the reaction reach its equilibri...
by Louise Lin 2B
Fri Jan 10, 2020 5:01 pm
Forum: Ideal Gases
Topic: Chatelier’s Principle
Replies: 8
Views: 61

Re: Chatelier’s Principle

Le Chatelier's Principle basically means that a reaction will adapt to any changes as a response to minimize the effect of the change. This means that if pressure is increased or decreased, Le Chatelier's principle tells us that the reaction will adjust to keep K, the equilibrium constant, stable.
by Louise Lin 2B
Fri Jan 10, 2020 4:59 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Response of Equilibria to Change
Replies: 3
Views: 33

Response of Equilibria to Change

Can someone re-explain the real reason behind why reactions, upon changing the pressure, respond to minimize the effect of increasing pressure? Dr. Lavelle said in class that many of us learned the shortcut version, wherein upon increasing pressure, the reaction would go opposite the direction of th...
by Louise Lin 2B
Sun Dec 08, 2019 11:33 pm
Forum: Bronsted Acids & Bases
Topic: amphoteric
Replies: 7
Views: 99

Re: amphoteric

adding on to the above replies, an example of a common amphoteric molecule is water. Water can act as either an acid or base depending on the reactions.
by Louise Lin 2B
Sun Dec 08, 2019 11:30 pm
Forum: Conjugate Acids & Bases
Topic: single arrow vs double arrow
Replies: 2
Views: 68

Re: single arrow vs double arrow

Yes, double arrows typically indicate that the reaction does not completely dissociate and is reversible. Single arrows indicate that the reaction dissociates completely.
by Louise Lin 2B
Sun Dec 08, 2019 10:30 pm
Forum: Lewis Acids & Bases
Topic: Strong/Weak Acids and Bases
Replies: 4
Views: 104

Re: Strong/Weak Acids and Bases

I’d like to add that strong bases include group 1 hydroxides, alkaline earth metal hydroxides, and group 1 and 2 oxides.
by Louise Lin 2B
Sun Dec 08, 2019 10:06 pm
Forum: Lewis Acids & Bases
Topic: Lewis Acids.
Replies: 4
Views: 61

Re: Lewis Acids.

Lewis acids are electron acceptors, meaning they usually receive lone pairs. The molecule that is more electron deficient is typically the Lewis acid. On the other hand, Lewis bases are electron donors, so they give away lone pairs.
by Louise Lin 2B
Sun Dec 08, 2019 9:56 pm
Forum: Amphoteric Compounds
Topic: examples
Replies: 2
Views: 60

Re: examples

One example of an amphoteric compound is water, H2O.
Water as a base:
HCl(aq) + H2O(l) —> H3O+(aq) + Cl-(aq)

Water as an acid:
H2O(l) + NH2-(aq) —> OH-(aq) + NH3(aq)
by Louise Lin 2B
Sat Nov 30, 2019 8:23 pm
Forum: Amphoteric Compounds
Topic: compounds
Replies: 5
Views: 34

Re: compounds

An amphoteric compound can donate and/or accept protons. Amphoteric compounds have both acid and base-like properties. Some examples of amphoteric compounds are water and amino acids (which make up proteins).
by Louise Lin 2B
Sat Nov 30, 2019 4:23 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Value of pH
Replies: 8
Views: 52

Re: Value of pH

It's possible to calculate a negative pH, but in practice in a lab, negative pH can't really be tested for.
by Louise Lin 2B
Sat Nov 30, 2019 4:18 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: [H3O+] and [OH-]
Replies: 3
Views: 53

Re: [H3O+] and [OH-]

to convert between [H3O+] and [OH-], use [H3O+]=10-pHmol . L-1. pH+pOH = 14 maximum, so we can use this equation to find and convert between [H3O+] and [OH-].
by Louise Lin 2B
Sat Nov 30, 2019 3:11 pm
Forum: Amphoteric Compounds
Topic: Textbook question 6A.17
Replies: 1
Views: 34

Re: Textbook question 6A.17

Elements that are in and close to the diagonal line of metalloids usually make amphoteric oxides. If you look at figure 6A.7 on page 450, Bi2O3 is classified as an amphoteric oxide.
by Louise Lin 2B
Sat Nov 30, 2019 1:25 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Do strong acids dissociate completely in water?
Replies: 7
Views: 65

Re: Do strong acids dissociate completely in water?

Strong acids have a higher concentration of hydrogen ions than weak acids. This means that for strong acids, all of the hydrogen ions dissociate immediately, while weak acids dissociate more slowly.
by Louise Lin 2B
Sun Nov 24, 2019 5:43 pm
Forum: Biological Examples
Topic: Drawing biological examples
Replies: 1
Views: 30

Re: Drawing biological examples

I believe we'll be expected to know how to draw some of the coordination compounds for the test, but they might give us the chemical formula, since that seems to be the pattern from previous tests.
by Louise Lin 2B
Sun Nov 24, 2019 5:37 pm
Forum: Biological Examples
Topic: TMs' biological functions
Replies: 3
Views: 32

Re: TMs' biological functions

Chromium as an element in general is a beneficial to one's health, but doing some research after Dr. Lavelle's lecture, the best chromium supplementation is said to be chromium picolinate, which is a coordination compound.
by Louise Lin 2B
Sun Nov 24, 2019 5:26 pm
Forum: Biological Examples
Topic: cisplatin
Replies: 6
Views: 68

Re: cisplatin

The pros of cisplatin are that they kill cancer cells very effectively. A minor con is that cisplatin also works on healthy cells, but Dr. Lavelle mentioned that the degree at which they kill healthy cells is relatively less than the amount of cancer cells killed.
by Louise Lin 2B
Sun Nov 24, 2019 3:33 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Cation outside coordination sphere
Replies: 2
Views: 28

Re: Cation outside coordination sphere

It is possible for cations to be outside the coordinate sphere if the net charge of the coordinate sphere is negative. This would allow for positive cations to be attracted to the outside of the coordinate sphere as a whole.
by Louise Lin 2B
Fri Nov 22, 2019 5:39 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: transition metals
Replies: 3
Views: 33

Re: transition metals

Transition metals having multiple oxidation states allows them to lose electrons fairly easily when compared to the metals in group 1 and group 2. This allows them to transfer electrons more easily as well, like the previous commentator stated.
by Louise Lin 2B
Fri Nov 15, 2019 8:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: clouds of electrons
Replies: 3
Views: 40

Re: clouds of electrons

Only the lone and bonded pairs pertaining to the central atom are important to determining the regions of electron density in molecule shape and structure.
by Louise Lin 2B
Fri Nov 15, 2019 8:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bent v. straight shape
Replies: 3
Views: 40

Re: bent v. straight shape

Bent shapes occur when the molecule has lone pairs due to electron repulsion. For ths example, then, the model with lone pairs would be the one with a bent shape.
by Louise Lin 2B
Fri Nov 15, 2019 8:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent shape and angles
Replies: 6
Views: 50

Re: Bent shape and angles

If the central atom has two bonded pairs and either one or two lone pairs, this would result in the bent shape. The bond angle would be smaller if the central atom has two lone pairs because of electron repulsion.
by Louise Lin 2B
Fri Nov 15, 2019 8:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: varying VSEPRs
Replies: 7
Views: 58

Re: varying VSEPRs

The shape will not vary, since, even though resonance structures exist, we count single, double, and triple bonds as one grouping.
by Louise Lin 2B
Fri Nov 15, 2019 8:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Notation used in VSEPR
Replies: 8
Views: 56

Re: Notation used in VSEPR

The formula is derived from A being the central atom, X being the atoms bonded to the central atom (with the subscript being the number of atoms bonded to the central atom), and E being the number of lone pairs the central atom has.
by Louise Lin 2B
Fri Nov 15, 2019 8:00 pm
Forum: Electronegativity
Topic: water solubility
Replies: 4
Views: 59

Re: water solubility

If compounds have a higher electronegativity, they are more polar. Since water itself is a polar molecule, it would dissolve polar compounds well, especially compounds with higher electronegativity.
by Louise Lin 2B
Sun Nov 10, 2019 12:50 pm
Forum: Dipole Moments
Topic: BOND STRENGTH
Replies: 4
Views: 35

Re: BOND STRENGTH

I believe this will depend on if the molecule has any lone pairs left and the structure of the molecule. It would be better if you had a specific example in mind, too!
by Louise Lin 2B
Sun Nov 10, 2019 12:46 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Can polar molecules be more polar than another?
Replies: 5
Views: 38

Re: Can polar molecules be more polar than another?

Yes, polar molecules can be more polar than another. You can tell when you look at the difference in electronegativity of the atoms in the molecules.
by Louise Lin 2B
Sun Nov 10, 2019 12:35 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Lone pairs on central atom
Replies: 3
Views: 28

Re: Lone pairs on central atom

Yes, lone pairs affect how polar a molecule is. Take H2O for example: oxygen has two lone pairs, which makes water a polar molecule. There is a higher negative partial charge on the oxygen end, and a higher positive partial charge on the hydrogen end.
by Louise Lin 2B
Sun Nov 10, 2019 12:32 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarisability and Size
Replies: 3
Views: 44

Re: Polarisability and Size

Polarizability increases as the volume of the atoms increase. This means that polarizability typically increases down a group and decreases left to right in a period. High polarizability makes molecules have larger dispersion forces that allow them to form temporary dipoles more easily. Bonds betwee...
by Louise Lin 2B
Sun Nov 10, 2019 12:22 pm
Forum: Bond Lengths & Energies
Topic: polarizability
Replies: 9
Views: 46

Re: polarizability

Polarizablility increases generally when volume occupied increases. This means, as a periodic trend, it increases down a group, but decreases across a period. Polarizability determines what kinds of bonds the atom will form, which then determines the state of the molecule.
by Louise Lin 2B
Sat Nov 02, 2019 3:58 pm
Forum: Electronegativity
Topic: Electronegativity and charge
Replies: 2
Views: 27

Re: Electronegativity and charge

A bigger difference in electronegativity does not mean a higher charge, but any difference larger than 1.7 or 1.8 mean that ionic bonds will form. Electronegativity increases as you move left to right on a period.
by Louise Lin 2B
Sat Nov 02, 2019 3:51 pm
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge
Replies: 5
Views: 60

Re: formal charge

Arianna Perea 3H wrote:Does FC determine where we make double bonds?

Yes, it does! The FC equation needs to know the number of paired and unpaired electrons, and the most stable structures are those with a net charge of zero. FC can determine where double bonds will be when calculated.
by Louise Lin 2B
Sat Nov 02, 2019 3:33 pm
Forum: Ionic & Covalent Bonds
Topic: AgF,AgI,AgCl
Replies: 2
Views: 28

Re: AgF,AgI,AgCl

Exactly! As you move down a group, covalent characteristics of a bond increases, which causes a decrease in electronegativities of the bonded atoms and a decrease in polarity. Since water is a polar molecule, it becomes harder for it to dissolve silver halides as the covalent character increases.
by Louise Lin 2B
Sat Nov 02, 2019 3:28 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 1
Views: 27

Re: Covalent Bonds

Water is typically more effective when breaking ionic compounds because the ions are attracted to the polar water molecules, which break the ionic compounds apart. Water is not as effective when breaking covalent bonds because many covalent compounds are nonpolar. Since water is polar, and many cova...
by Louise Lin 2B
Sat Nov 02, 2019 12:01 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic/Covalent
Replies: 6
Views: 50

Re: Ionic/Covalent

Ionic bonds have covalent properties that depend on the polarizability of the anion and the cation's polarizing power. Ionic bonds have more covalent character when the anion is more polarizable or when the cation has high polarizing power.
by Louise Lin 2B
Sun Oct 27, 2019 2:34 am
Forum: Resonance Structures
Topic: Resonance
Replies: 4
Views: 41

Re: Resonance

Adding on to the replies above, make sure to always calculate the formal charge of each atom to make sure that you have arranged the best possible structure. Not all molecules with double or triple bonds will have resonant structures, so it is important to make sure.
by Louise Lin 2B
Sun Oct 27, 2019 2:07 am
Forum: Ionic & Covalent Bonds
Topic: 2A.23
Replies: 5
Views: 54

Re: 2A.23

a) Mg3As2
b) In2S3
c) AlH3
d) H2Te
e) BiF3
by Louise Lin 2B
Sun Oct 27, 2019 2:03 am
Forum: Ionic & Covalent Bonds
Topic: Does the Octet Rule apply to Boron?
Replies: 14
Views: 108

Re: Does the Octet Rule apply to Boron?

The octet rule does not apply to boron because it only has 6 electrons. It also does not apply strictly when elements are in the third period or higher. This is because of the presence of d-orbital electrons allowing for exceptions when chemically bonded.
by Louise Lin 2B
Sun Oct 27, 2019 1:56 am
Forum: Ionic & Covalent Bonds
Topic: Double bond placement
Replies: 15
Views: 108

Re: Double bond placement

Adding on to the poster above, the location of double and triple bonds will depend on where the octet rule can be accommodated. They cannot be replaced wherever “because of resonance,” because we must also determine if the atom has resonance structures in the first place. If there is resonance, then...
by Louise Lin 2B
Sun Oct 27, 2019 1:49 am
Forum: Trends in The Periodic Table
Topic: atomic Radii
Replies: 11
Views: 70

Re: atomic Radii

In line with all above answers, yes, atomic radii increases the more electrons there are. However it is important to also note that atomic radii increases not per electron, but per subshell. Each subshell will hold a certain amount of electrons, and atomic radii increases with each new subshell.
by Louise Lin 2B
Sat Oct 19, 2019 11:20 pm
Forum: Quantum Numbers and The H-Atom
Topic: Principal Quantum Number
Replies: 3
Views: 48

Re: Principal Quantum Number

The principle quantum number is "calculated" depending on the energy level that the electron is on. We can find it by looking at the period the element is on. As for atom excitation, I'm not too sure about that either...
by Louise Lin 2B
Sat Oct 19, 2019 11:14 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D.13
Replies: 2
Views: 38

Re: 1D.13

a) when n=7, there are 7 quantum numbers: 0,1,2,3,4,5,6
b) when an electron is in a 6d-subshell there are five values of ml: -2,-1,0,1,2
c) when an electron is in a 3p-subshell, there are three values for ml: -1,0,1
d) when n=4, there are four subshells: 4s, 4p,4d, 4f
by Louise Lin 2B
Sat Oct 19, 2019 2:44 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Same spin
Replies: 10
Views: 92

Re: Same spin

Adding on to the above comment, two electrons with the "same spin" means that they are both either spinning upward or spinning downward. Take the element carbon: the atomic number is 6, so the electron configuration would be 1s 2 2s 2 2p 2 . The 1s and 2s shells are both at the maximum occ...
by Louise Lin 2B
Sat Oct 19, 2019 2:39 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Coulombs's Law
Replies: 2
Views: 30

Re: Coulombs's Law

r as distance between two charges is more accurate. r can describe the distance between two electrons, or the distance between and electron and a proton. At your high school, your class may have calculated using r as the distance between an electron and proton (which are in the nucleus) and just cal...
by Louise Lin 2B
Sat Oct 19, 2019 2:36 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 4s vs. 3d
Replies: 6
Views: 51

Re: 4s vs. 3d

The 4s orbital actually has higher energy than the 3d orbital if the 4s orbital is occupied by electrons. So, when we write out the electron configurations, the 3d orbital goes before 4s!
by Louise Lin 2B
Fri Oct 11, 2019 9:52 pm
Forum: Properties of Electrons
Topic: where does it travel
Replies: 2
Views: 28

Re: where does it travel

Electrons travel the different energy levels that an atom has. They don't necessarily follow a wavelength; rather, an electron acts as both a wave and a particle.
by Louise Lin 2B
Fri Oct 11, 2019 9:33 pm
Forum: Properties of Electrons
Topic: Electron Energy Levels
Replies: 8
Views: 60

Re: Electron Energy Levels

The number of energy levels that an electron can jump to depends on the number of energy levels an atom of the element has. The number of energy levels an atom has depends on its placement on the periodic table.
by Louise Lin 2B
Fri Oct 11, 2019 9:31 pm
Forum: Properties of Light
Topic: Image in lecture
Replies: 2
Views: 49

Re: Image in lecture

In the two images he showed during the lecture, the model with the connected oscillating wave meant that the electron circulating the nucleus was at an energy level like n=3, where the level is an integer, or whole number. The model that had the disconnected wave means that it does not "work;&q...
by Louise Lin 2B
Fri Oct 11, 2019 2:06 pm
Forum: Properties of Light
Topic: Application on Microwaves
Replies: 1
Views: 37

Re: Application on Microwaves

Microwave ovens are dangerous because they fit about 1 kilowatt of power inside a small box. Regular microwave radiation may have less energy than 1 photon of light, but imagine concentrating a kilowatt's worth of microwave radiation into a small box. This amount of power is how food gets reheated i...
by Louise Lin 2B
Fri Oct 11, 2019 2:00 pm
Forum: *Black Body Radiation
Topic: Black Body Radiation
Replies: 6
Views: 132

Re: Black Body Radiation

A "black body" is a concept that is created to imagine the complete absence of color or light or anything. Professor Lavelle said that a true black does not actually exist, so black bodies are the hypotheticals we would imagine.
by Louise Lin 2B
Thu Oct 03, 2019 4:20 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Fundamentals E1
Replies: 4
Views: 86

Re: Fundamentals E1

Start by visualizing the molecules side by side, strung together! The 144 pm they give you for radius should be calculated into the diameter of the atom (so 288 pm). First, like you said, convert 1 mole of Ag into number of atoms with Avogadro's number. Next, multiply your answer by 288 pm to find o...
by Louise Lin 2B
Thu Oct 03, 2019 4:15 pm
Forum: Significant Figures
Topic: Sig Figs and Rounding
Replies: 4
Views: 67

Re: Sig Figs and Rounding

Typically, it's best to save rounding for the end, just so your answer is as precise as possible! ;)))) If we round in the middle steps, the answer may turn out different than intended.
by Louise Lin 2B
Thu Oct 03, 2019 4:11 pm
Forum: SI Units, Unit Conversions
Topic: Discussion Credit
Replies: 7
Views: 126

Re: Discussion Credit

For discussion credit, we'll be turning in 5 homework problems and do 5 posts; questions and replies both count! :))
by Louise Lin 2B
Mon Sep 30, 2019 11:19 pm
Forum: SI Units, Unit Conversions
Topic: Calculator Question
Replies: 13
Views: 207

Re: Calculator Question

It sounds like a plain old scientific or four-function should serve you well. Personally, I use the Casio - fx115ES Plus Scientific calculator. I remember that AP Chem in high school didn't really need a graphing calculator, so I suppose that's why Chem 14A doesn't necessarily require one, either.
by Louise Lin 2B
Sun Sep 29, 2019 7:40 pm
Forum: SI Units, Unit Conversions
Topic: Memorizing Metric Conversions
Replies: 8
Views: 174

Re: Memorizing Metric Conversions

Hey there!

You did receive a reply already, but here's a similar mnemonic that I used in high school that might be of help to you:
Kings Have Died Under Dreadful Circumstances: Meteors
They don't always make sense, but if you create your own mnemonic, that might help you more! :))
by Louise Lin 2B
Sun Sep 29, 2019 7:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 150
Views: 4892

Re: Advice from a Medical Student - Part II [ENDORSED]

Your journey sounds like it has been amazing! As someone that also wants to go into the medical field, this is very inspiring. And you certainly made me more excited for Dr. Lavelle's class. Do you currently have other interests outside the medical field, and do you still have time to engage in them...

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