Search found 97 matches
- Wed Mar 11, 2020 4:58 pm
- Forum: Second Order Reactions
- Topic: linear graph
- Replies: 7
- Views: 550
Re: linear graph
For a second order reaction the graph of ln[A] vs time will yield a straight line
- Wed Mar 11, 2020 4:51 pm
- Forum: First Order Reactions
- Topic: Half Life
- Replies: 13
- Views: 849
Re: Half Life
It would probably only explicitly ask for half-life
- Wed Mar 11, 2020 4:47 pm
- Forum: First Order Reactions
- Topic: Half Life Equations
- Replies: 10
- Views: 616
Re: Half Life Equations
They should be provided, but it may be easier to memorize which equation goes with which order.
- Wed Mar 11, 2020 4:27 pm
- Forum: First Order Reactions
- Topic: rate constants
- Replies: 30
- Views: 1529
Re: rate constants
Because concentration can never be a negative value, it is always positive.
- Wed Mar 11, 2020 4:24 pm
- Forum: First Order Reactions
- Topic: Determining Order
- Replies: 7
- Views: 480
Re: Determining Order
Martina wrote:You can also look at units of the rate constant if it is given and be able to tell what the order is.
Yes! for zero order reactions the units are M/s. First order is s^-1, and second order is 1/M.s.
- Wed Mar 11, 2020 4:13 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 374455
Re: Final Jitters
I always try to get there a bit earlier to calm my nerves, just helps familiarize myself with the testing area.
- Wed Mar 11, 2020 4:08 pm
- Forum: General Science Questions
- Topic: What are Workshops?
- Replies: 10
- Views: 894
Re: What are Workshops?
Step-up sessions are more like a step by step explanation of topics learned in class, specifically designed to essentially relearn material. Workshops, however are more focused on extra practice for topics.
- Wed Mar 11, 2020 3:58 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3642049
Re: Post All Chemistry Jokes Here
me @Lavelle
- Wed Mar 11, 2020 3:39 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3642049
- Wed Mar 11, 2020 3:33 pm
- Forum: General Science Questions
- Topic: Test 2 Grades [ENDORSED]
- Replies: 23
- Views: 1637
Re: Test 2 Grades [ENDORSED]
Anushka Chauhan2B wrote:During disc
What about those whose discussion was cancelled?
- Wed Mar 11, 2020 3:26 pm
- Forum: General Science Questions
- Topic: Review Packet
- Replies: 14
- Views: 1268
Re: Review Packet
Subashni Rajiv 1K wrote:Lyndon just posted practice problems for Electrochemistry and Kinetics that can be found if you search up ENDGAME.
Oh wow, thank you! I wonder how information will be relayed given circumstances.
- Wed Mar 11, 2020 3:25 pm
- Forum: General Science Questions
- Topic: Chemistry Final
- Replies: 16
- Views: 1234
Re: Chemistry Final
Not sure, the format has yet to be announced, but given the circumstances I assume it will either be free response or maybe a bit of both.
- Wed Mar 11, 2020 3:23 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 567152
Re: Saying Thank You to Dr. Lavelle
WOW! I love this! Thank you so much Dr. Lavelle for being a professor that is not only passionate about what he is teaching, but is so clearly passionate about his students and teaching in general. Chemistry may be a hard science, but you have given me a strong foundation to learn on for the past tw...
- Wed Mar 11, 2020 3:11 pm
- Forum: General Science Questions
- Topic: Final
- Replies: 7
- Views: 631
Re: Final
Anushka Chauhan2B wrote:You should probs study it just in case
Also, considering the changes made to the final, I think it will be more based on new material.
- Wed Mar 11, 2020 3:10 pm
- Forum: General Science Questions
- Topic: Final
- Replies: 7
- Views: 631
Re: Final
I would study it, just in case, but considering that it was tested heavily on the midterm and we have covered a lot of new material, I would say it won't be too acid/base heavy, probably like 30% material from before the midterm and 70% since the midterm.
- Tue Mar 10, 2020 12:03 am
- Forum: Van't Hoff Equation
- Topic: What's the purpose of Van't Hoff?
- Replies: 5
- Views: 534
Re: What's the purpose of Van't Hoff?
Van't Hoff's equation is used to relates changes in equilibrium to the change in temperature. So you can solve for Keq if you know the equilibrium constant of another reaction.
- Mon Mar 09, 2020 11:18 pm
- Forum: Zero Order Reactions
- Topic: Graphs
- Replies: 13
- Views: 1392
Re: Graphs
We may not have to draw the graphs, but we will probably need to know what graphs of first order, second order, and zeroth order reactions look like vs time.
- Mon Mar 09, 2020 10:59 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4986
Re: Kc vs Kp
In that instance, you would use Kp, Kc is used for molar concentration.
- Mon Mar 09, 2020 10:52 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 374455
Re: Final Jitters
For me, something that always helps is to get to the test location early. Just helps calm my nerves about familiarizing and getting comfortable with the area. Also, when the testing begins, try not to focus too much on what everyone else is doing, and tune out anything that may be happening in the t...
- Sun Feb 09, 2020 7:46 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: irreversible and reversible
- Replies: 3
- Views: 293
Re: irreversible and reversible
In a reversible expansion, temperature is constant because the work is the sum of the infinitesimal small changes. Since these changes are really small, the energy lost from the system through work is instantly supplied with heat from the surroundings. Therefore, the temperature does not change for...
- Sun Feb 09, 2020 7:43 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated systems
- Replies: 4
- Views: 365
Re: Isolated systems
OPEN: both energy and matter transferred
CLOSED: energy but not matter transferred
ISOLATED: neither energy nor matter
CLOSED: energy but not matter transferred
ISOLATED: neither energy nor matter
- Sun Feb 09, 2020 7:41 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: closed system
- Replies: 7
- Views: 385
Re: closed system
Because in a closed system, matter cannot be transferred, but energy can.
- Sun Feb 09, 2020 7:38 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: isolated system
- Replies: 8
- Views: 505
Re: isolated system
In a calorimeter, energy and matter both CANNOT be transferred between the system and surroundings because of the tight seal, making it an isolated system
- Sun Feb 09, 2020 7:35 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Significance of open, closed, isolated
- Replies: 22
- Views: 1167
Re: Significance of open, closed, isolated
It's important to spot the difference because it'll help better understand the relationship between the system and surroundings and to understand the corresponding variables for each system (i.e. open system=constant pressure, among others)
- Sun Feb 09, 2020 7:30 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated// Energy
- Replies: 11
- Views: 609
Re: Isolated// Energy
No, neither energy nor matter can be transferred between a system and surroundings in an isolated system.
- Sun Feb 09, 2020 7:27 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Thermodynamics
- Replies: 6
- Views: 317
Re: Thermodynamics
Aman Sankineni 2L wrote:Heat transfer to a system is positive, and heat transfer from a system is negative. W is positive if work is done by the system, and negative if work is done on the system.
So I would say that in this case, both are negative.
- Sun Feb 09, 2020 7:21 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Thermodynamic system
- Replies: 3
- Views: 222
Re: Thermodynamic system
Open System: both matter and energy
Closed System: energy, but not matter
Isolated System: neither energy nor matter
Closed System: energy, but not matter
Isolated System: neither energy nor matter
- Sun Feb 09, 2020 7:14 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Intensive vs Extensive
- Replies: 7
- Views: 367
Re: Intensive vs Extensive
An intensive property is a property in which the amount of material in a system does not affect its value or quantity. For an extensive property, however, the amount of material in a system does affect its value
- Sat Feb 08, 2020 5:21 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Reversible vs Irriversible
- Replies: 3
- Views: 182
Re: Reversible vs Irriversible
A good tell for for reversible and irreversible is that irreversible reactions occur under constant pressure
- Sat Feb 08, 2020 5:19 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Topics on the Midterm
- Replies: 22
- Views: 1147
Re: Topics on the Midterm
Acids and bases, equilibrium, all of thermochemistry, and the first page of the thermodynamics concepts on lavelle's outline
- Sat Feb 08, 2020 5:07 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Review Sheet
- Replies: 3
- Views: 258
Re: Review Sheet
I would use q=mC(deltaT) and honestly just plug in the information given
- Sat Feb 08, 2020 4:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hf and Hc
- Replies: 3
- Views: 155
Re: Hf and Hc
Technically, they could be used the same way in the equation, but H subscript c is the enthalpy of combustion.
- Sat Feb 08, 2020 4:41 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 4
- Views: 147
Re: Bond Enthalpies
Normally bond enthalpies should be stated, unless it is the most stable form of the naturally occurring element, in which case it does not have a bond enthalpy.
- Sat Feb 08, 2020 4:35 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: State Property
- Replies: 5
- Views: 192
Re: State Property
A state property is something (a quantity) that is independent of the path taken to reach a specific value or endpoint. Enthalpy is the total heat of a system and is also a state property.
- Sat Feb 08, 2020 12:53 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: H=q
- Replies: 4
- Views: 285
Re: H=q
Just to be safe, I would not assume anything if the problem doesn't state whether or not the reaction occurs under constant pressure
- Sat Feb 08, 2020 12:52 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Delta H and qp
- Replies: 8
- Views: 206
Re: Delta H and qp
Delta H is only equal to qp under constant pressure considering that is what qp means, but the two should not be used interchangeable.
- Sat Feb 08, 2020 12:46 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: reversible vs irreversible work
- Replies: 7
- Views: 481
Re: reversible vs irreversible work
I think a good tell is whether or not the reaction occurs under constant pressure. That would make it an irreversible reaction.
- Sat Feb 08, 2020 12:40 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units for heat of reaction
- Replies: 9
- Views: 296
Re: Units for heat of reaction
Yup! The standard enthalpy of formation for products and/or reactants should be in kJ/mol
- Sat Feb 08, 2020 12:12 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard enthalpies of formation
- Replies: 5
- Views: 134
Re: Standard enthalpies of formation
Yes, you multiply them each by their respective stoichiometric coefficient.
- Sun Jan 12, 2020 5:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K
- Replies: 10
- Views: 407
Re: K
Vuong_2F wrote:Kc is the equilibrium constant when it's found using concentrations, while Kp is the equilibrium constant when it's found using partial pressures.
It's important to note that they are all calculated the same way
- Sun Jan 12, 2020 5:37 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 19
- Views: 1718
Re: Le Chatelier's Principle
Le Chateliers principle is used any time a reaction at equalibrium is changed in any way
- Sun Jan 12, 2020 5:27 pm
- Forum: Ideal Gases
- Topic: Test 1
- Replies: 7
- Views: 396
Re: Test 1
Not too sure but his outlines should let us know exactly what concepts we have to know for Test 1
- Sun Jan 12, 2020 5:17 pm
- Forum: Ideal Gases
- Topic: Topics on Test 1
- Replies: 37
- Views: 1406
Re: Topics on Test 1
Most likely just Outline 1 and 2
- Sun Jan 12, 2020 5:14 pm
- Forum: Ideal Gases
- Topic: PV = nRT
- Replies: 16
- Views: 1982
Re: PV = nRT
Pressure x Volume = Moles x Ideal Gas Constant x Temperature (in kelvin)
- Sun Dec 08, 2019 6:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Linear VSEPR model
- Replies: 21
- Views: 1351
Re: Linear VSEPR model
If the molecule had 1 or 2 lone pairs it would then become bent. If it had 3, that would make it linear
- Sun Dec 08, 2019 6:41 pm
- Forum: Hybridization
- Topic: Writing the hydrization
- Replies: 10
- Views: 768
Re: Writing the hydrization
The difference between 2sp2 and sp2 is the statement of the energy level (n=2), but unless the question specifies that the energy level needs to be stated, then its not required.
- Sun Dec 08, 2019 6:38 pm
- Forum: Hybridization
- Topic: Pi bond
- Replies: 10
- Views: 787
Re: Pi bond
Yes, because a pi bond requires a plane of symmetry for the bond to form and hold
- Sun Dec 08, 2019 6:37 pm
- Forum: Hybridization
- Topic: double and triple bonds
- Replies: 6
- Views: 527
Re: double and triple bonds
they do not hybridize in pi double or triple bonds
- Sun Dec 08, 2019 6:35 pm
- Forum: Hybridization
- Topic: 2sp2 and sp2
- Replies: 10
- Views: 870
Re: 2sp2 and sp2
Unless the question specifically asks for the energy level to be specified, sp2 should be fine
- Sun Dec 08, 2019 6:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bond angles
- Replies: 16
- Views: 1232
Re: bond angles
Lone pairs will make a bond angle less than (<) the angle of the shape it is derived from, because the electron repulsion from lone pairs condenses the angles of the bonds.
- Sun Dec 08, 2019 6:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Disobeying the octect rule
- Replies: 4
- Views: 292
Re: Disobeying the octect rule
Yes, they are able to break the octet rule and have an expanded orbital
- Sun Dec 08, 2019 6:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: vsepr formula
- Replies: 7
- Views: 625
Re: vsepr formula
The VSEPR formula means the question is asking you to write out the AXE formula.
- Sun Dec 08, 2019 6:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: cis vs trans
- Replies: 5
- Views: 472
Re: cis vs trans
in a cis molecule the function groups are on the same side of the molecule, whereas in a trans molecule the function groups are on different sides. Another note, trans and cis molecules are actually isomers of each other.
- Sun Dec 08, 2019 6:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AXE formula
- Replies: 7
- Views: 551
Re: AXE formula
The E is the number of lone pairs on the central atom
- Sun Dec 08, 2019 6:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T-shape
- Replies: 21
- Views: 1728
Re: T-shape
A t-shape molecule is derived from a trigonal bipyramidal but has 2 lone pairs and 3 bonds, making it resemble the letter T
- Sun Dec 08, 2019 6:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T-shape
- Replies: 21
- Views: 1728
Re: T-shape
A t-shape molecule is derived from a trigonal bipyramidal but has 2 lone pairs and 3 bonds, making it resemble the letter T
- Sun Dec 08, 2019 6:09 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining polarity from VSPER
- Replies: 4
- Views: 473
Re: Determining polarity from VSPER
The VSEPR shape would be a better indication of polarity, a little trick to remember is that lone pairs will make a molecule polar, but it is always a good idea to draw the shape
- Sun Dec 08, 2019 6:03 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR of S02
- Replies: 4
- Views: 857
Re: VSEPR of S02
The VSEPR for SO2 is AX2E because the central atom (S) is bonded to two oxygen atoms and has one lone pair.
- Sun Dec 08, 2019 5:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Shape
- Replies: 31
- Views: 2993
Re: Bent Shape
1 or 2 lone pairs can create a bent shape
- Sun Dec 08, 2019 5:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 4294
Re: Bent vs linear
Looking at the number of lone pairs can help identify whether or not the molecule is bent or linear.
- Sun Nov 17, 2019 9:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: suare planar
- Replies: 2
- Views: 161
Re: suare planar
Technically XEF4, or any square planar is derived from an octahedral, but has two lone pairs. What makes it rare if the fact that the central atom has an expanded octet because it receives 4 bonds then has 2 lone pairs added on.
- Sun Nov 17, 2019 9:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lewis Structures
- Replies: 6
- Views: 618
Re: Lewis Structures
Once you can make the most stable lewis structure, the regions of electron density, and and the lone pairs, you should be able to correspond these numbers with a specific shape. You'll need to memorize the names and the characteristics for this one. For example, ammonia (NH3) has 3 regions of electr...
- Sun Nov 17, 2019 9:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs
- Replies: 10
- Views: 564
Re: Lone Pairs
Lone pairs repel the other atoms within a molecule, compressing angles and making them smaller
- Sun Nov 17, 2019 9:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: single vs. double/triple bonds
- Replies: 4
- Views: 238
Re: single vs. double/triple bonds
In comparison to their interaction with the lone pairs of bonding pairs of other atoms, they stay together as the lone pairs cause repulsion
- Sun Nov 17, 2019 9:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Equatorial lone pairs
- Replies: 2
- Views: 185
Re: Equatorial lone pairs
By removing the equatorial atoms, the space between remaining atoms is maximized with degree angles of 120 between 3 atoms and 90 between two
- Sun Nov 17, 2019 6:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dispersion
- Replies: 5
- Views: 345
Re: Dispersion
I would definitely review dipole--dipole, london dispersion, and hydrogen bonding, as those are the ones we focused on in class, however, I would also recommend looking over the others such as induced dipole-induced dipole etc.
- Sun Nov 17, 2019 6:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shapes
- Replies: 7
- Views: 457
- Sun Nov 17, 2019 6:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2
- Replies: 19
- Views: 888
Re: Test 2
If the most stable lewis structure is drawn, you will be able to properly determine the regions of electron density and the lone pairs which will then allow you to identify the correct VESPR shape
- Sun Nov 17, 2019 6:08 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion
- Replies: 6
- Views: 332
Re: Repulsion
Lone Pair--Lone Pair > Lone Pair--Bonding > Bonding Pair--Bonding Pair
- Sun Nov 17, 2019 5:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dipole Moment
- Replies: 3
- Views: 262
Re: Dipole Moment
Polarity itself deals with the difference in electrically charged poles of a molecule, so if the charges do not cancel, we can assume they are not equally shared, meaning the molecule is polar.
- Sun Nov 17, 2019 5:54 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Order
- Replies: 3
- Views: 278
Re: Bond Order
I don't think the bond order is particularly important, in VESPR models we are looking more at the regions of electron density.
- Sun Nov 17, 2019 5:45 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Do we have to memorize the names of shapes and/or the bond angles?
- Replies: 7
- Views: 527
Re: Do we have to memorize the names of shapes and/or the bond angles?
Yes, I believe we do. We will be tested on all of outline 4, and certain topics in outline 3
- Sun Nov 17, 2019 5:23 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion Strength
- Replies: 4
- Views: 264
Re: Repulsion Strength
Lone Pair--Lone Pair > Lone Pair--Bonding > Bonding Pair--Bonding Pair
- Sun Nov 17, 2019 5:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bonded and Lone Pairs in VSEPR
- Replies: 4
- Views: 356
Re: Bonded and Lone Pairs in VSEPR
Lone pairs DO influence molecular shape, but only atom positions are used to name the actual shape.
- Sun Nov 17, 2019 5:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR repulsion model
- Replies: 8
- Views: 619
Re: VSEPR repulsion model
Bond angles also cannot be calculated, per say, using VESPR, but it can help you determine in in terms of steric numbers. For example, we know that methane (CH4) is a tetrahedral, and all bond angles are 109.5, but ammonia (NH3) which has the same principle shape as methane, except now has a lone pa...
- Sun Nov 17, 2019 4:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR repulsion model
- Replies: 8
- Views: 619
Re: VSEPR repulsion model
In a VESPR model, there is repulsion between lone pairs and bonding pairs. In terms of strength, LP--LP Bonds > LP--Bonding > Bonding--Bonding. Because atoms want to be spread out in VESPR models, the lone pairs cause an increased amount of repulsion.
- Sun Oct 27, 2019 5:48 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 6
- Views: 947
Re: Electronegativity
While we generally view the trend (up and across to the right) as equally important, the truth is that going up has a bit of a greater effect on electronegativty than moving across a period. This is because the higher groups have less shells and therefore feel more pull from other atoms.
- Sun Oct 27, 2019 5:38 pm
- Forum: Electronegativity
- Topic: Transition Metals and Periodic Table Trends
- Replies: 2
- Views: 203
Re: Transition Metals and Periodic Table Trends
In a problem given to you, the valence electrons will normally be given as well because they vary
- Sun Oct 27, 2019 5:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: Resonance
- Replies: 10
- Views: 425
Re: Resonance
A molecule that has resonance has multiple lewis dot structures with double or triple bonds that can appear in multiple places, not necessarily that it has different lewis dot structures because chemical species that experience resonance technically have the same lewis structure, just different vers...
- Sun Oct 27, 2019 5:23 pm
- Forum: Ionic & Covalent Bonds
- Topic: Double bond placement
- Replies: 15
- Views: 884
Re: Double bond placement
A good place to start is when looking at the number of electrons in a chemical species, and drawing the lewis dot structures, if a species is meant to have multiple bonds, the number of e- drawn should not match the total number of electrons needed.
- Sun Oct 27, 2019 5:15 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons
- Replies: 16
- Views: 777
Re: Valence Electrons
By counting along the period, the number that represents element you are looking for will tell you the valence electrons. For example, Nitrogen is the 5th element in its period, and Florine is the 7th. However, Phosphorous is also has 5 valence electrons, but it is in a different period than Nitrogen.
- Sun Oct 20, 2019 10:32 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Why is 4s before 3d?
- Replies: 9
- Views: 996
Re: Why is 4s before 3d?
This would be an important topic to know for the midterm! So when you look at the periodic table, electrons fill orbitals in that order. So since the elements that have 4s orbitals are in front of those that have valence electrons in the 3d state, they fill the 4s first. :) Over all, it's important...
- Sun Oct 20, 2019 6:32 pm
- Forum: Trends in The Periodic Table
- Topic: Exceptions in Periodic Trends
- Replies: 2
- Views: 2857
Re: Exceptions in Periodic Trends
Yes, there are a few exceptions to the general trends we see on the periodic table. Electronegativity increases as you move to the right of the PT from the metals up to the halogens, but the noble gases do not have electronegativities (unless forced under very extreme pressure/conditions) because t...
- Sun Oct 20, 2019 6:24 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Hund's rule and Pauli Exclusion Principle
- Replies: 14
- Views: 849
Re: Hund's rule and Pauli Exclusion Principle
The relationship between the two lies with the fact that we use both Hund's Rule and the Pauli Exclusion Principle in conjunction with the Building-Up principle in order to properly create/write experimentally observed electron configurations.
- Sun Oct 20, 2019 6:16 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 8
- Views: 316
Re: Orbitals
The reason why Scandium is written as [Ar] 3d1 4s2 is because after the 20th element in the periodic table (Calcium), the 3d orbitals have a slightly lower energy than the 4s orbitals. Therefore, you would start filling the 3d orbitals until it is full. The 4s orbital is filled first because it is ...
- Sun Oct 20, 2019 6:10 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Probably a really quick question.
- Replies: 2
- Views: 120
Re: Probably a really quick question.
Yes, there are nodal planes for all except the s- orbital. Just as the p- orbital has one nodal plane, the d- orbital has two, and so forth.
- Sun Oct 13, 2019 4:55 pm
- Forum: Properties of Electrons
- Topic: Diffraction
- Replies: 6
- Views: 232
Re: Diffraction
You can think of it similar to building structure, constructive interference is when the waves are in phase, almost providing support, creating a greater amplitude of the wavelength. Destructive, however, is when the wavelengths are out of phase and opposite to one another. This causes the energy of...
- Sun Oct 13, 2019 4:46 pm
- Forum: Photoelectric Effect
- Topic: Avogadro's number
- Replies: 7
- Views: 481
Re: Avogadro's number
You usually divide by Avogadro's number when the question gives you the number of molecules and is asking you to find the number of moles of a compound. Remember that avagadro's number (6.626 x 10^23) is the number of molecules or atoms that are in a single mole, so by dividing by this number, you ...
- Sun Oct 13, 2019 4:39 pm
- Forum: Properties of Light
- Topic: speed of light
- Replies: 10
- Views: 352
Re: speed of light
Drake Choi_1I wrote:I remember learning in physics something about mediums and light. I know that a vacuum is where light can travel fastest. What is the next fastest medium?
I believe water is the next fastest at about 2.25 x 10^8 m.sec^-1, but we'll mainly be working with light in a vacuum
- Sun Oct 13, 2019 4:35 pm
- Forum: Properties of Light
- Topic: speed of light
- Replies: 10
- Views: 352
Re: speed of light
Throughout this quarter, and for the purpose of this class, the speed of light will remain a constant equal to 3.0 x 10^8 m.sec^-1, however outside of this setting, it is not so absolute, and actually changes relative to the the mediums it travels through.
- Sun Oct 13, 2019 4:28 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Why do the orbitals of an atom only hold a certain amount of electrons?
- Replies: 7
- Views: 1054
Re: Why do the orbitals of an atom only hold a certain amount of electrons?
The shape of the orbital is what determines how many electrons it can house. Electrons also must spin in different directions and because there are only two options, there can only be two electrons on each orbital. It is important to note that each level has a different number of orbitals (s=1, p=3,...
- Sun Oct 13, 2019 4:06 pm
- Forum: DeBroglie Equation
- Topic: When to use DeBroglie Equation
- Replies: 16
- Views: 700
Re: When to use DeBroglie Equation
De Broglie's equation can be used to calculate the energy of anything with measurable wavelength properties OTHER THAN light. Typically speaking, a DeBroglie wavelength less than 10^-15 does not have detectable wavelength properties. Hope this helps!
- Wed Oct 02, 2019 11:07 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Dilution and Molarity Questions
- Replies: 8
- Views: 667
Re: Dilution and Molarity Questions
Sometimes molarity and dilution problems can seem a bit wordy and overwhelming. For me, I always begin by writing down the number values that they give me and determining which are useful depending on what part of the problem I am at. That was I can interpret the real meaning of all the information ...
- Wed Oct 02, 2019 10:58 am
- Forum: Empirical & Molecular Formulas
- Topic: Rounding [ENDORSED]
- Replies: 12
- Views: 826
Re: Rounding [ENDORSED]
Rounding can be a bit tricky and if possible, I would keep the rounding to a minimum while you work out the problem. However, if you do, make sure to use the proper sig figs and your answer should be okay.
- Wed Oct 02, 2019 10:52 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Accuracy and Precision [ENDORSED]
- Replies: 4
- Views: 265
Re: Accuracy and Precision [ENDORSED]
I think the equation you're referring to is the one where you subtract your lowest measured value from your highest value to record as precision, but I don't think we will be doing this with actual numerical values. I think it's more for us the understand the difference between the two and the indiv...
- Wed Oct 02, 2019 10:47 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Balancing Equations [ENDORSED]
- Replies: 25
- Views: 2074
Re: Balancing Equations [ENDORSED]
How are we supposed to know what number to multiply by in order to attain whole integers? Knowing if we need to multiply by 2 or 3 to reach a whole number is easy, but what about when the solution is more complicated? normally, the numbers should be pretty easy fractions, but if they turn out a lit...
- Wed Oct 02, 2019 10:38 am
- Forum: Significant Figures
- Topic: How Many significant figures to use ?
- Replies: 9
- Views: 3303
Re: How Many significant figures to use ?
Generally when rounding or using sig figs, looking at the original problem can help you gauge how many sig figs to use, and normally I would look at the LEAST precise measurement (the more decimal places the more precise). For example, if you are given a problem with the values 3.2, 5.72, and 0.32, ...