Search found 89 matches

by Anna O 2C
Fri Feb 22, 2019 9:46 pm
Forum: Balancing Redox Reactions
Topic: standard reduction potential
Replies: 2
Views: 12

Re: standard reduction potential

E will not change since it is intensive however depending on the direction of the equation you might change its sign.
by Anna O 2C
Fri Feb 22, 2019 9:44 pm
Forum: Balancing Redox Reactions
Topic: OH- H+ and H2O in balancing redox reactions
Replies: 5
Views: 801

Re: OH- H+ and H2O in balancing redox reactions

The amount of OH- or H+ is based off of whether it is a basic or an acidic reaction.
by Anna O 2C
Fri Feb 22, 2019 9:43 pm
Forum: Balancing Redox Reactions
Topic: Balancing problem
Replies: 3
Views: 24

Re: Balancing problem

To answer your question I think the Cl- is being oxidized in the HClO- it is gaining an electron in one of the compounds.
by Anna O 2C
Fri Feb 22, 2019 9:40 pm
Forum: Balancing Redox Reactions
Topic: OH-, Adams, Disc 1A
Replies: 3
Views: 16

Re: OH-, Adams, Disc 1A

You had OH- when dealing with bases because they are going to result in the addition of more bases as they accept hydrogens.
by Anna O 2C
Sun Feb 17, 2019 6:40 pm
Forum: Phase Changes & Related Calculations
Topic: Negative and Positive values of delta H and w
Replies: 5
Views: 29

Re: Negative and Positive values of delta H and w

A negative delta H means that the heat transfer is negative and thus the system is losing heat.
by Anna O 2C
Sun Feb 17, 2019 6:39 pm
Forum: Phase Changes & Related Calculations
Topic: Slope of heating curve
Replies: 6
Views: 32

Re: Slope of heating curve

It is a shallower slope because it is a slower process to reaching the next phase change whereas for low heat capacity, it takes less energy and heat and thus has a steep slope because it reaches the next phase easier.
by Anna O 2C
Sun Feb 17, 2019 6:37 pm
Forum: Phase Changes & Related Calculations
Topic: Chapter 8 number 21
Replies: 4
Views: 29

Re: Chapter 8 number 21

Heat lost by the metal should be a negative value while the water receiving the heat should have a positive value.
by Anna O 2C
Sun Feb 17, 2019 6:36 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 6
Views: 54

Re: Phase Changes

To add on, often times Dr. Lavelle might also ask questions that require you to "recreate" the shape of the graph and the changes occurring at each phase.
by Anna O 2C
Wed Feb 13, 2019 9:00 am
Forum: Phase Changes & Related Calculations
Topic: ΔH vs ΔU?
Replies: 5
Views: 47

ΔH vs ΔU?

Can someone explain why heat transfer is ΔU at constant volume and interpreted as ΔH at constant pressure?
by Anna O 2C
Tue Feb 12, 2019 7:34 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: How Much of the Outline Do I Need to Know?
Replies: 2
Views: 36

How Much of the Outline Do I Need to Know?

Since we are stopping before Gibbs Free Energy for the midterm, how far into the Thermodynamics outline do we have to know?
by Anna O 2C
Sun Feb 10, 2019 10:36 pm
Forum: Ideal Gases
Topic: The Difference between Q and Kc
Replies: 11
Views: 71

Re: The Difference between Q and Kc

Kc is the value of Q taken only at equilibrium while Q is the same ratio but taken at anytime during the reaction, not specifically at equilibrium.
by Anna O 2C
Sun Feb 10, 2019 10:35 pm
Forum: Ideal Gases
Topic: ICE Table Values
Replies: 7
Views: 38

Re: ICE Table Values

Generally I would recommend using only pressures and concentrations because that is what practice problems in the textbook use.
by Anna O 2C
Sun Feb 10, 2019 10:33 pm
Forum: Ideal Gases
Topic: Lyndon's review session
Replies: 7
Views: 132

Re: Lyndon's review session

To add on, make sure you show up early because his fill up very quickly.
by Anna O 2C
Sun Feb 10, 2019 10:30 pm
Forum: Ideal Gases
Topic: pH and pOH
Replies: 17
Views: 94

Re: pH and pOH

Often times if they don't say it outright, you can infer through whether they are referring to the concentrations of acids or bases in a solution.
by Anna O 2C
Sun Feb 10, 2019 10:29 pm
Forum: Ideal Gases
Topic: Approximations for ICE
Replies: 14
Views: 56

Re: Approximations for ICE

To add on, make sure to always verify at the end that your approximation was less than 5% otherwise the approximation won't hold and you need to use the formula for finding roots.
by Anna O 2C
Sun Feb 10, 2019 10:27 pm
Forum: Ideal Gases
Topic: atm vs. bar?
Replies: 19
Views: 151

Re: atm vs. bar?

They simply correspond with different values, but distinguishing between them is essential in order to use the correct R constant value.
by Anna O 2C
Fri Feb 08, 2019 9:39 am
Forum: Phase Changes & Related Calculations
Topic: Heat and Condensation
Replies: 9
Views: 44

Re: Heat and Condensation

Condensation releases heat and is exothermic because molecules are going from the gas phase to the liquid phase by making bonds. Creating bonds will release excess energy as the two molecules move to a lower energy level so that energy will be released back into the surroundings in the form of heat.
by Anna O 2C
Fri Feb 08, 2019 9:38 am
Forum: Phase Changes & Related Calculations
Topic: Heating Curve
Replies: 4
Views: 31

Re: Heating Curve

The slope corresponds with the coinciding heat capacity of that specific liquid. The higher the heat capacity, the more heat is require to raise its temperature so it will take longer for the temperature to rise thus leasing to a smaller slope and less steep curve.
by Anna O 2C
Fri Feb 08, 2019 9:35 am
Forum: Phase Changes & Related Calculations
Topic: sections
Replies: 4
Views: 31

Re: sections

To add on to what's above, the best way to prepare for all these sections in my experience is to follow along with the practice problems that show the steps and then self test yourself on more ! Good luck!
by Anna O 2C
Fri Feb 08, 2019 9:32 am
Forum: Phase Changes & Related Calculations
Topic: Units of enthalpy
Replies: 5
Views: 31

Re: Units of enthalpy

Enthalpy is usually represented in kJ/mol, and many questions will present measurements in either J or smaller quantities, so it's always important to check to make sure you do any necessary conversions ! :)
by Anna O 2C
Sun Feb 03, 2019 11:58 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 2
Views: 16

Re: Phase Changes

Energy is being used to elevate energy within the system, not raise the temperature which is why they can be different phases but same constant temperature.
by Anna O 2C
Sun Feb 03, 2019 11:57 pm
Forum: Phase Changes & Related Calculations
Topic: Steam vs Boiling Water
Replies: 10
Views: 73

Re: Steam vs Boiling Water

Steam is at a higher energy level than boiling water is so even though they are existing at the same temperature, the extra energy and thus burning ability is transferred to a burn victim when the steam condenses and lowers temperature after contact with skin.
by Anna O 2C
Sun Feb 03, 2019 11:55 pm
Forum: Phase Changes & Related Calculations
Topic: State Function
Replies: 10
Views: 53

Re: State Function

Work is dependent on its transition from its final to initial stage so it cannot be considered a state functions in the way enthalpy can.
by Anna O 2C
Sun Feb 03, 2019 11:54 pm
Forum: Phase Changes & Related Calculations
Topic: Type of systems
Replies: 12
Views: 60

Re: Type of systems

Isolated systems have to be closed but they also don't allow the passage of heat or energy with their s.urroundings
by Anna O 2C
Wed Jan 23, 2019 4:13 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: autoprotolysis
Replies: 5
Views: 46

Re: autoprotolysis

Whether or not it is on the test, deriving it is simple because you only have to take the negative log of the concentrations to get the respective pH and pOH. It is important in general to remember the relationships like those such as Kw because they will come in handy on the midterm and final as we...
by Anna O 2C
Wed Jan 23, 2019 4:11 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 7th edition 5J.5 part b
Replies: 3
Views: 35

Re: 7th edition 5J.5 part b

The reactants are favored because in a closed vessel with solids and gases, the increase in pressure isn't going to affect the solid, it will only affect the gases. Because of this, increased pressure will cause the reaction to move towards the side with less moles of gas and thus less partial press...
by Anna O 2C
Wed Jan 23, 2019 3:55 pm
Forum: Phase Changes & Related Calculations
Topic: Water turning into ice rapidly
Replies: 2
Views: 25

Water turning into ice rapidly

I've seen videos where ice can be frozen to 0°C and remain in liquid form, but when you shake it, it immediately turns into slushy and freezes over. Does this have to do with the water graph we looked at today where there is a solid chunk of time/transition between solid and liquid? Where even thoug...
by Anna O 2C
Wed Jan 23, 2019 3:49 pm
Forum: Phase Changes & Related Calculations
Topic: Endothermic or Exothermic
Replies: 20
Views: 358

Re: Endothermic or Exothermic

As stated above, condensation is exothermic. When you look at it from a molecular standpoint, the molecules are transitioning from the gas phase to the liquid phase. Individual atoms are thus coming together and bonding with each other, a process that release excess heat as the bonded molecule is mo...
by Anna O 2C
Tue Jan 15, 2019 12:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q vs. K
Replies: 5
Views: 41

Re: Q vs. K

Q is calculated in the same way as K, only it can be taken at anytime during the reaction instead of K which is exclusively valued at the time of equilibrium. Because Q is the same ratio as K, you can utilize its value in relation to K to determine where the reaction lies in its accordance to the gi...
by Anna O 2C
Tue Jan 15, 2019 12:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration Affecting K
Replies: 7
Views: 48

Re: Concentration Affecting K

Kc will remain constant throughout the whole reaction as long as the temperature remains constant. When the concentrations change, the reaction will simply respond by producing more or less of either reactant or product to filter the introduced additives into the equilibrium. For example, if you add...
by Anna O 2C
Tue Jan 15, 2019 12:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Equilibrium values
Replies: 2
Views: 16

Re: Calculating Equilibrium values

To add on, if only moles or concentrations are given for one side, it is generally safe to assume that these will be the only initial values given and that your x value will be taken away from these given values. This is because in your resulting equation, the x needs to have a reference point to an...
by Anna O 2C
Tue Jan 15, 2019 12:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE charts
Replies: 3
Views: 16

Re: ICE charts

Generally, I think we focus on using concentrations. However, 5I.23 in the 7th edition textbook version uses mole values for the ICE tables instead of concentration.
by Anna O 2C
Tue Jan 08, 2019 9:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: hw questions - points
Replies: 9
Views: 73

Re: hw questions - points

Posting on Chemistry Community can take on many forms. You can ask a question about lecture, discussion, textbook problems, homework, and even administrative questions such as study groups. In addition, you can answer people's questions or add onto an existing discussion. Any substantial post will c...
by Anna O 2C
Tue Jan 08, 2019 9:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.7
Replies: 5
Views: 56

Re: 11.7

Could you explain what problem you are referring to? Writing out the problem would be easiest.
by Anna O 2C
Tue Jan 08, 2019 9:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs. Kp
Replies: 7
Views: 52

Re: Kc vs. Kp

Adding on, Kp is used for gases in the reaction, ignoring solids and liquids. When a reaction includes aqueous solutions, you can't use Kp because liquids can't have pressure, just concentrations.
by Anna O 2C
Tue Jan 08, 2019 5:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentrations of products/reactants
Replies: 6
Views: 43

Re: Concentrations of products/reactants

Adding on, K is referring to the concentrations held to the specific power and ratio as stated in the balanced equilibrium equation given in the problem. Knowing the concentrations won't do you any good if they aren't held to the correct power within the fraction for K.
by Anna O 2C
Sun Dec 09, 2018 3:14 pm
Forum: Hybridization
Topic: 4.93
Replies: 2
Views: 54

Re: 4.93

I don't know what question you're referring to but for sp3 must be 4 regions of electron density. You might be missing a lone pair or if it's a coordination bond there might be a hydrogen attached that isn't shown.
by Anna O 2C
Sun Dec 09, 2018 3:12 pm
Forum: Octet Exceptions
Topic: breaking the octet
Replies: 2
Views: 40

Re: breaking the octet

Adding to the last reply, they can expand into their d orbitals because at row 3 the 3s and 3p also include 3d even though it's in the 4th row.
by Anna O 2C
Sun Dec 09, 2018 3:10 pm
Forum: Bond Lengths & Energies
Topic: Shape of molecule
Replies: 4
Views: 38

Re: Shape of molecule

The surface area is larger for the rod shaped molecules so there will be more surface area for the two to interact upon, resulting in tighter and stronger bonds.
by Anna O 2C
Sun Dec 09, 2018 3:08 pm
Forum: Air Pollution & Acid Rain
Topic: Acid Rain Formation
Replies: 6
Views: 85

Re: Acid Rain Formation

Also a good point to know is that the water and sulfuric acid mix to create h2so4
by Anna O 2C
Sat Dec 08, 2018 5:41 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining the Coordination number
Replies: 3
Views: 16

Determining the Coordination number

Is the coordination number determined by the number of atoms attached to a central atom, the number of bonds (including double and triple) or the number of regions of electron density?
by Anna O 2C
Sun Dec 02, 2018 5:24 pm
Forum: Hybridization
Topic: CH2O hybridization
Replies: 9
Views: 243

Re: CH2O hybridization

The hybridization will be sp2 because the s orbital can only form 1 bond and the 2 p orbitals must be combined with the s orbital to allow for 3 bonds to be made by the central atom. This results in the hybridization with 1 s orbital and 2 p orbitals, so sp2.
by Anna O 2C
Sun Dec 02, 2018 5:20 pm
Forum: Hybridization
Topic: Hybridization
Replies: 5
Views: 38

Re: Hybridization

Yes, because the s orbital can only form one bond and the p orbital can form 3 bonds but the center atom in a tetrahedral shaped molecule forms 4 bonds so the s and 3 p orbitals must combine, resulting in an sp3 hybridized orbital.
by Anna O 2C
Sun Dec 02, 2018 5:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Compound
Replies: 1
Views: 21

Re: Coordination Compound

Generally, this can be solved by creating a Lewis structure of the molecule. Once you make this, you can see which atoms have lone pairs available for bonding or which atoms in a compound are able to add another bond even if they have a full octet already as in the case of phosphorus which can have ...
by Anna O 2C
Sun Dec 02, 2018 5:07 pm
Forum: Balancing Chemical Reactions
Topic: Final Exam Q: Memorizing Polyatomic Ions
Replies: 2
Views: 35

Re: Final Exam Q: Memorizing Polyatomic Ions

I don't believe you will have to memorize the names of all the polyatomic ions, but at this point in the course you should know the names of several of the molecules that we use regularly such as cyanide and carbonate. Other than that, the final is highly unlikely to have a section dedicated to just...
by Anna O 2C
Mon Nov 26, 2018 7:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Can an octahedral be polar?
Replies: 4
Views: 35

Can an octahedral be polar?

I'm looking for examples of polar molecules with an octahedral shape and I'm struggling to find any. Is there an exception saying that octahedral shapes are usually nonpolar or are there any good example of octahedral structures that are polar? Thanks!
by Anna O 2C
Sun Nov 25, 2018 11:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.5 Bond Angle
Replies: 2
Views: 27

Re: 4.5 Bond Angle

Adding on to the reply above me, the lone pairs distort the attached atoms more than normal bonding pairs do because when they aren't engaged in a bond, electrons move more freely and this causes them to be more repulsive. Because of this, the lone pairs take up more room than atoms do and thus pus...
by Anna O 2C
Sun Nov 25, 2018 5:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 6
Views: 41

Re: Polarity

Polarity depends on symmetry of the molecule. Sometimes lone pairs can cancel out, such as in the case of AX4E2, which is square planar. Since the lone pairs are directly opposite each other, the repulsion caused by them cancel out, and thus the atoms remain in a symmetrical position. Adding onto t...
by Anna O 2C
Sun Nov 25, 2018 5:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma and Pi bonds
Replies: 6
Views: 35

Re: Sigma and Pi bonds

Pi bonds result because you can't have 2 sigma bonds in a double bond. Sigma bonds are the shortest and connect the two atoms most directly. Any other bond that occurs will have to arch around the existing bond to reach the other atom and thus become a pi bond. Every bond formed after the initial si...
by Anna O 2C
Sun Nov 25, 2018 5:50 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Lengths
Replies: 10
Views: 119

Re: Bond Lengths

If a structure has multiple bonds then the total molecule will have bonds the average length of all the present bonds. A molecule that has resonance has multiple possible bond placements in a Lewis structure, but this simply translates to having bonds that are averaged out over the different bond le...
by Anna O 2C
Mon Nov 19, 2018 4:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dipole moments
Replies: 8
Views: 55

Re: Dipole moments

Another hint in figuring out whether a molecule is going to be polar is its geometry. If the same atom is spaced around the central atom such as CH4 then the electronegativities around the central atom will be equal in magnitude and symmetrical and thus be nonpolar; for shapes with multiple atoms, t...
by Anna O 2C
Mon Nov 19, 2018 4:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis Structure of OSbCL3 and shape
Replies: 2
Views: 27

Re: Lewis Structure of OSbCL3 and shape

Adding on^^ For the Molecular shape, you know that Sb is the central atom. From there, we have 2 Chlorines and 2 Oxygens attached to it. Since there aren't any lone pairs on the central atom we know that there are only 4 regions of electron density giving us AX4 which corresponds with a tetrahedral ...
by Anna O 2C
Mon Nov 19, 2018 4:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: multiple sigma bonds
Replies: 4
Views: 46

Re: multiple sigma bonds

The sigma bond is going to the shortest and closest bond. When you form extra bonds, those electrons can't invade the bond space already occupied by the sigma bond so they have to arch over in order to reach the other atom. Kind of like if you're hugging someone and then another third person joins t...
by Anna O 2C
Mon Nov 19, 2018 4:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma and Pi Bonds
Replies: 3
Views: 40

Re: Sigma and Pi Bonds

The course page for this unit says we need to know how to distinguish sigma and pi bonds by their shapes, properties, and component orbitals. Just remember that the double bond isn't really "=" but one of the bonds will have to arch over the other. I remember this because pies are round an...
by Anna O 2C
Mon Nov 19, 2018 4:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Atom Placement
Replies: 4
Views: 36

Re: Atom Placement

It won't really matter in the 3D version because even though 4 atoms might seem like they are next to each other on paper, they will actually all be an equal distance from the atoms next to each other in the tetrahedral shape. As long as you know it's a tetrahedral shape, that implies that they are ...
by Anna O 2C
Sun Nov 18, 2018 7:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: lone pairs and bond angle
Replies: 6
Views: 57

Re: lone pairs and bond angle

Lone pairs have more repulsive energy than electrons engaged in a bond between two atoms because they aren't being "tied down" by the positive energy of two atoms. Thus they have more "push" per say and can repel nearby atoms more than bonded electrons can. When this happens, the...
by Anna O 2C
Sun Nov 18, 2018 7:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 8
Views: 73

Re: Lone Pairs

Lone pairs affect the shape of a molecule because electrons have negative and repulsive energy. They are constantly being tugged at and pushing each other away. When they are sitting as a lone pair, they have more freedom to buzz about near their home base atom. When the electrons are engaged in a b...
by Anna O 2C
Sun Nov 18, 2018 7:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 7th edition 2E. 21
Replies: 4
Views: 43

Re: 7th edition 2E. 21

Test questions, unless given experimental data to permit exact bond angles, will generally accept "less than 109.5" because, without an experiment, one can't really know the extent to which the lone pairs can alter the position of the bonded atoms because there isn't a calculation to tell ...
by Anna O 2C
Sun Nov 18, 2018 7:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Shape
Replies: 5
Views: 40

Re: Determining Shape

The regions of high e- density will determine the shape but lone pairs have more repulsion energy than electrons in bonds so the lone pairs will alter the bond angles. VSEPR models only take into account where the atoms are, not where the lone pairs are, but the lone pairs need to be considered beca...
by Anna O 2C
Sun Nov 11, 2018 10:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 7th edition 2E. 5
Replies: 2
Views: 21

Re: 7th edition 2E. 5

I would recommend drawing the structure with the implied "3Dness" (the dashes and the solid black triangles) since that is the only way you can correctly label it a tetrahedral. If you draw it in the 2D version, the bond angles won't be displayed properly because that would imply that the ...
by Anna O 2C
Sun Nov 11, 2018 10:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar vs Nonpolar
Replies: 5
Views: 54

Re: Polar vs Nonpolar

When there is a difference in electronegativity, one atom is going to have more of a pull on that electron that the other, meaning the electrons will spend more of their time near that atom, so the negativity will be largely on that side of the molecule. That side of the molecule thus has a partial ...
by Anna O 2C
Sun Nov 11, 2018 10:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 6
Views: 51

Re: Molecular Shape

The dashed lines means that there is an attraction between those two dipole moments. For example, if you draw multiple H2O molecules the dashed lines will be connecting oxygen and hydrogen atoms on the two different molecules because one has a positive and one has a negative dipole so they are attra...
by Anna O 2C
Sun Nov 11, 2018 10:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 5
Views: 52

Re: Molecular Shape

I'm pretty sure a molecule is going to be linear as long as there aren't any lone pairs on the central atom. When the molecule is linear, there aren't any lone pairs taking up space and pushing the other attached atoms away, thus bending the molecular shape. I think this only applies to chains of at...
by Anna O 2C
Sun Nov 04, 2018 11:28 pm
Forum: Ionic & Covalent Bonds
Topic: Nitrogen or Oxygen as Central Atom
Replies: 2
Views: 32

Re: Nitrogen or Oxygen as Central Atom

Nitrogen would be the central atom because the central atom should be the one that is least electronegative because it is more likely to share electrons. Central atoms should be chosen based on their electronegativity, not ionization energy. Hope this helps!
by Anna O 2C
Sun Nov 04, 2018 11:12 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization Energies
Replies: 13
Views: 117

Re: Ionization Energies

This is also because Helium is a noble gas. Since it also has very few orbitals and energy shells in the ground state, the electrons experience little to no shielding and thus require extreme amounts of energy to remove electrons.
by Anna O 2C
Thu Nov 01, 2018 9:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: Assigning Quantum Numbers to Different Elements
Replies: 2
Views: 25

Re: Assigning Quantum Numbers to Different Elements

ml is the magnetic quantum number. This just tells you which orbital the electron is in. For example, an electron in chromium could either be in the -2, -1, 0, 1, or 2 orbital. ms is spin magnetic quantum number. This tells you whether the electron has up spin or down spin (the two electrons in an ...
by Anna O 2C
Thu Nov 01, 2018 5:52 pm
Forum: Quantum Numbers and The H-Atom
Topic: Assigning Quantum Numbers to Different Elements
Replies: 2
Views: 25

Assigning Quantum Numbers to Different Elements

I'm struggling to clarify how to utilize ml and ms for quantum numbers. I understand that n is the period of the element, and that l is for the orbital the valence electrons, but I'm not sure on the concept behind the ml and ms as well as the numbers when an element is in the d-block. Say for exampl...
by Anna O 2C
Thu Nov 01, 2018 5:41 pm
Forum: Ionic & Covalent Bonds
Topic: 2A.23 7th edition (Chemical Formula)
Replies: 3
Views: 56

Re: 2A.23 7th edition (Chemical Formula)

^^ To add on, Hydrogen is willing to give away its one electron to become more stable and Aluminum wants electrons in order to get closer to the noble gas configuration and more stability, so Aluminum will take 3 Hydrogens that each provide 1 electron.
by Anna O 2C
Thu Nov 01, 2018 5:38 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Configuration of a Cation (hw problem 3.21 part d)
Replies: 4
Views: 40

Re: Electron Configuration of a Cation (hw problem 3.21 part d)

Yep! Ag sits one electron away from having a full d orbital so the second electron from the 5s orbital instead occupies the d orbital to bring it to a full and therefore more stable state. Therefore the 4d becomes 4d10 and the 5s becomes 5s1.
by Anna O 2C
Thu Nov 01, 2018 11:29 am
Forum: Ionic & Covalent Bonds
Topic: Removing the second electron
Replies: 8
Views: 79

Re: Removing the second electron

Removing the second electron generally requires more energy because of the proton's net positive charge. When the first electron is removed, the positive pull of the protons gains more power over the fewer electrons still left in orbital. Thus, more energy is then required from an outside source to ...
by Anna O 2C
Fri Oct 26, 2018 3:02 pm
Forum: Ionic & Covalent Bonds
Topic: Calculating number of valence electrons in bonds
Replies: 5
Views: 41

Re: Calculating number of valence electrons in bonds

^^ And after that you can compare the separate molecules and their charges. For example, SO42- will have 4×6=24 O electrons (4 O and each one has 6 e-) and then S will have 6 e-, for a combined total of 30 e-. Then, since the molecule SO42- has a charge of -2, that means there are 2 extra electrons ...
by Anna O 2C
Fri Oct 26, 2018 2:57 pm
Forum: Ionic & Covalent Bonds
Topic: Chemical Bonding
Replies: 8
Views: 85

Re: Chemical Bonding

Today we defined a chemical bond, discussed ionic bonds and how they differ between main group and p-block elements, covalent bonds, the octet rule, and basic Lewis structures as well as the Lewis structures of polyatomic species.
by Anna O 2C
Fri Oct 26, 2018 2:54 pm
Forum: Ionic & Covalent Bonds
Topic: Polar and Non-polar Covalent bonds
Replies: 4
Views: 133

Re: Polar and Non-polar Covalent bonds

Also, the negativity will be concentrated on one side of the molecule/bond where one atom has a high electronegativity than the other. When this happens, even though both atoms are sharing the electron and thus attached to each other, the electron is more likely to be found closer to the atom with h...
by Anna O 2C
Fri Oct 26, 2018 2:51 pm
Forum: Ionic & Covalent Bonds
Topic: Ground State Electron Configurations
Replies: 7
Views: 64

Re: Ground State Electron Configurations

Using the noble gases in the configuration allows us to only mention the most relevant electrons on the atom. When it comes to bonds and equations, the valence electrons are generally the only ones interacting directly with other atoms to it is both cumbersome and repetitive to mention all the lower...
by Anna O 2C
Tue Oct 23, 2018 9:35 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Series and Wavelengths
Replies: 4
Views: 52

Re: Series and Wavelengths

Why is it that, for the Lyman and Balmer Series, the lines are super close and then there is a huge space in between and then more close sets of lines? I feel like as the energy level goes up, it should take almost exponentially higher energy from light to eject an electron.
by Anna O 2C
Mon Oct 22, 2018 3:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration
Replies: 5
Views: 41

Re: Electron Configuration

^ Similarly to what was mentioned above, using the noble gases is fine just as we learned in lecture unless the question particularly requests for the full length version of such a configuration.
by Anna O 2C
Mon Oct 22, 2018 3:29 pm
Forum: Administrative Questions and Class Announcements
Topic: Required knowledge for test/midterm [ENDORSED]
Replies: 13
Views: 237

Re: Required knowledge for test/midterm [ENDORSED]

While you won't have to remember the equations for the test, it'll be important to remember the SI units for these formulas such as whether a formula requires meters or kilometers and converting accordingly.
by Anna O 2C
Mon Oct 22, 2018 3:20 pm
Forum: Administrative Questions and Class Announcements
Topic: Writing in Pen
Replies: 13
Views: 216

Re: Writing in Pen

I agree with the erasable pens. They come in 5 packs on amazon and most have pretty durable erasers. Just make sure the pens you get don't smear when you erase! The low quality pens will leave marks on your paper so test them out beforehand.
by Anna O 2C
Tue Oct 16, 2018 8:00 am
Forum: Properties of Electrons
Topic: Electrons in a stable state?
Replies: 6
Views: 81

Re: Electrons in a stable state?

So electrons in higher energy states contain higher potential energy, while electrons in lower energy states contain lower potential energy? Does this mean that electrons in higher energy states are more unstable than electrons in lower energy states? So isn't that why it's easier for electrons to ...
by Anna O 2C
Sun Oct 14, 2018 11:09 pm
Forum: Properties of Electrons
Topic: Electrons in a stable state?
Replies: 6
Views: 81

Electrons in a stable state?

I know that an electron requires energy from light in order to be excited and pushed up to the next energy level, and that an electron will give off energy when it returns back to ground state in the form of photons, but I don't understand where the energy is kept while an electron is buzzing around...
by Anna O 2C
Sun Oct 14, 2018 11:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 86
Views: 25270

Re: Advice from a Medical Student [ENDORSED]

Thank you for this advice! I want to become a physician's assistant, so while I don't have to take the MCAT, PA school requires chemistry knowledge and math. Which math series did you take since I know that students going to medical school are required to take a full year of math? Thanks!
by Anna O 2C
Sun Oct 14, 2018 10:55 pm
Forum: General Science Questions
Topic: Periodic Table
Replies: 16
Views: 329

Re: Periodic Table

The safest way to prevent incorrect rounding early on is to use the entirety of the number given on the periodic table. With other pieces of data, rounding is more difficult to fully avoid, but avoiding rounding with Periodic elements will produce the most accurate answer possible, and then it can b...
by Anna O 2C
Sun Oct 14, 2018 10:52 pm
Forum: General Science Questions
Topic: Problem solving, intermediate steps
Replies: 2
Views: 114

Re: Problem solving, intermediate steps

The more steps you show, the easier it is for a TA to trace your steps backwards say you make a mistake. Often times if you make an error early on in a calculation such as in adding molar masses, but do the steps correctly (albeit with an incorrect value), you can still receive partial credit becaus...
by Anna O 2C
Sun Oct 14, 2018 10:48 pm
Forum: General Science Questions
Topic: Moles vs Number of Molecules
Replies: 5
Views: 156

Re: Moles vs Number of Molecules

The stoichiometric coefficients indeed are pertaining to moles of CH4. One mole of CH4 has 6.022x10^23 molecules of CH4, one mole of C, and 4 moles of H. A mole simply refers to the number of objects in a sample, and thus simplifies large quantities of atoms/molecules, just as it's easier to say a d...
by Anna O 2C
Sun Oct 14, 2018 10:40 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 113
Views: 33257

Re: Rusty on High School Chem [ENDORSED]

I have found that Dr. Lavelle is very effective at reviewing all necessary fundamentals needed for that lesson at the beginning of lecture. I took Honors Chemistry sophomore year and I am also a freshman this year. For me at least, the best way I've found to really get through the material is to wat...
by Anna O 2C
Sun Oct 14, 2018 10:34 pm
Forum: Properties of Light
Topic: Photons
Replies: 4
Views: 82

Re: Photons

For two photons to combine their energy to eject one electron, they would 1) need to hit the electron at the same time in order for both energies to add up to enough for an ejection which is extremely rare, and 2) like Dr. Lavelle said I think that the premise for our entry level quantum mechanics i...
by Anna O 2C
Sun Oct 14, 2018 10:29 pm
Forum: Properties of Light
Topic: Units for Wavelength
Replies: 7
Views: 33

Re: Units for Wavelength

Like mentioned above, if the question asks for specific units, use those. Otherwise, often times it comes down to the practicality and simplicity of an answer. If an answer in wavelength comes out to be 4.60×10^-9 meters, it is more efficient to simply say 4.60 nanometers. Often times formulas requi...
by Anna O 2C
Sun Oct 14, 2018 10:22 pm
Forum: Properties of Light
Topic: Light Intensity
Replies: 3
Views: 33

Re: Light Intensity

Light intensity has to do with the amount of photons in a light sample. This is especially important when considering threshold energy in quantum mechanics. Intensity doesn't affect the amount of electrons ejected from a sample if the individual photons in the sample don't have a high enough frequen...
by Anna O 2C
Sun Oct 14, 2018 10:16 pm
Forum: Student Social/Study Group
Topic: Note Taking
Replies: 25
Views: 801

Re: Note Taking

I have found that in general the best way for me is to take handwritten notes. I have several different colored pens that I utilize during class, and I switch between the different shades whenever we transition from lecture to explicit equations or from PowerPoint to hand drawn graphs/models. The co...

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